Change string compression encoding.
Encode the string compression flag as the least significant
bit of the "count" field, with 0 meaning compressed and 1
meaning uncompressed.
The main vdex file is a tiny bit larger (+28B for prebuilt
boot images, +32 for on-device built images) and the oat
file sizes change. Measured on Nexus 9, AOSP ToT, these
changes are insignificant when string compression is
disabled (-200B for the 32-bit boot*.oat for prebuilt boot
image, -4KiB when built on the device attributable to
rounding, -16B for 64-bit boot*.oat for prebuilt boot image,
no change when built on device) but with string compression
enabled we get significant differences:
prebuilt multi-part boot image:
- 32-bit boot*.oat: -28KiB
- 64-bit boot*.oat: -24KiB
on-device built single boot image:
- 32-bit boot.oat: -32KiB
- 64-bit boot.oat: -28KiB
The boot image oat file overhead for string compression:
prebuilt multi-part boot image:
- 32-bit boot*.oat: before: ~80KiB after: ~52KiB
- 64-bit boot*.oat: before: ~116KiB after: ~92KiB
on-device built single boot image:
- 32-bit boot.oat: before: 92KiB after: 60KiB
- 64-bit boot.oat: before: 116KiB after: 92KiB
The differences in the SplitStringBenchmark seem to be lost
in the noise.
Test: Run ART test suite on host and Nexus 9 with Optimizing.
Test: Run ART test suite on host and Nexus 9 with interpreter.
Test: All of the above with string compression enabled.
Bug: 31040547
Change-Id: I7570c2b700f1a31004a2d3c18b1cc30046d35a74
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 7cab97d..b2bfe42 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -4858,16 +4858,21 @@
case Primitive::kPrimShort:
case Primitive::kPrimChar:
case Primitive::kPrimInt: {
+ Register length;
+ if (maybe_compressed_char_at) {
+ length = locations->GetTemp(0).AsRegister<Register>();
+ uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
+ __ LoadFromOffset(kLoadWord, length, obj, count_offset);
+ codegen_->MaybeRecordImplicitNullCheck(instruction);
+ }
if (index.IsConstant()) {
int32_t const_index = index.GetConstant()->AsIntConstant()->GetValue();
if (maybe_compressed_char_at) {
- Register length = IP;
Label uncompressed_load, done;
- uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
- __ LoadFromOffset(kLoadWord, length, obj, count_offset);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ cmp(length, ShifterOperand(0));
- __ b(&uncompressed_load, GE);
+ __ Lsrs(length, length, 1u); // LSRS has a 16-bit encoding, TST (immediate) does not.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ b(&uncompressed_load, CS);
__ LoadFromOffset(kLoadUnsignedByte,
out_loc.AsRegister<Register>(),
obj,
@@ -4902,12 +4907,10 @@
}
if (maybe_compressed_char_at) {
Label uncompressed_load, done;
- uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
- Register length = locations->GetTemp(0).AsRegister<Register>();
- __ LoadFromOffset(kLoadWord, length, obj, count_offset);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ cmp(length, ShifterOperand(0));
- __ b(&uncompressed_load, GE);
+ __ Lsrs(length, length, 1u); // LSRS has a 16-bit encoding, TST (immediate) does not.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ b(&uncompressed_load, CS);
__ ldrb(out_loc.AsRegister<Register>(),
Address(temp, index.AsRegister<Register>(), Shift::LSL, 0));
__ b(&done);
@@ -5312,7 +5315,7 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
// Mask out compression flag from String's array length.
if (mirror::kUseStringCompression && instruction->IsStringLength()) {
- __ bic(out, out, ShifterOperand(1u << 31));
+ __ Lsr(out, out, 1u);
}
}
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index d868984..37322c6 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -2326,13 +2326,22 @@
if (maybe_compressed_char_at) {
uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
length = temps.AcquireW();
- __ Ldr(length, HeapOperand(obj, count_offset));
+ if (instruction->GetArray()->IsIntermediateAddress()) {
+ DCHECK_LT(count_offset, offset);
+ int64_t adjusted_offset = static_cast<int64_t>(count_offset) - static_cast<int64_t>(offset);
+ // Note that `adjusted_offset` is negative, so this will be a LDUR.
+ __ Ldr(length, MemOperand(obj.X(), adjusted_offset));
+ } else {
+ __ Ldr(length, HeapOperand(obj, count_offset));
+ }
codegen_->MaybeRecordImplicitNullCheck(instruction);
}
if (index.IsConstant()) {
if (maybe_compressed_char_at) {
vixl::aarch64::Label uncompressed_load, done;
- __ Tbz(length.W(), kWRegSize - 1, &uncompressed_load);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ Tbnz(length.W(), 0, &uncompressed_load);
__ Ldrb(Register(OutputCPURegister(instruction)),
HeapOperand(obj, offset + Int64ConstantFrom(index)));
__ B(&done);
@@ -2360,7 +2369,9 @@
}
if (maybe_compressed_char_at) {
vixl::aarch64::Label uncompressed_load, done;
- __ Tbz(length.W(), kWRegSize - 1, &uncompressed_load);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ Tbnz(length.W(), 0, &uncompressed_load);
__ Ldrb(Register(OutputCPURegister(instruction)),
HeapOperand(temp, XRegisterFrom(index), LSL, 0));
__ B(&done);
@@ -2405,7 +2416,7 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
// Mask out compression flag from String's array length.
if (mirror::kUseStringCompression && instruction->IsStringLength()) {
- __ And(out.W(), out.W(), Operand(static_cast<int32_t>(INT32_MAX)));
+ __ Lsr(out.W(), out.W(), 1u);
}
}
diff --git a/compiler/optimizing/code_generator_arm_vixl.cc b/compiler/optimizing/code_generator_arm_vixl.cc
index e69528e..254d908 100644
--- a/compiler/optimizing/code_generator_arm_vixl.cc
+++ b/compiler/optimizing/code_generator_arm_vixl.cc
@@ -3790,16 +3790,21 @@
case Primitive::kPrimShort:
case Primitive::kPrimChar:
case Primitive::kPrimInt: {
+ vixl32::Register length;
+ if (maybe_compressed_char_at) {
+ length = RegisterFrom(locations->GetTemp(0));
+ uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
+ GetAssembler()->LoadFromOffset(kLoadWord, length, obj, count_offset);
+ codegen_->MaybeRecordImplicitNullCheck(instruction);
+ }
if (index.IsConstant()) {
int32_t const_index = index.GetConstant()->AsIntConstant()->GetValue();
if (maybe_compressed_char_at) {
- vixl32::Register length = temps.Acquire();
vixl32::Label uncompressed_load, done;
- uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
- GetAssembler()->LoadFromOffset(kLoadWord, length, obj, count_offset);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ Cmp(length, 0);
- __ B(ge, &uncompressed_load);
+ __ Lsrs(length, length, 1u); // LSRS has a 16-bit encoding, TST (immediate) does not.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ B(cs, &uncompressed_load);
GetAssembler()->LoadFromOffset(kLoadUnsignedByte,
RegisterFrom(out_loc),
obj,
@@ -3827,12 +3832,10 @@
}
if (maybe_compressed_char_at) {
vixl32::Label uncompressed_load, done;
- uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
- vixl32::Register length = RegisterFrom(locations->GetTemp(0));
- GetAssembler()->LoadFromOffset(kLoadWord, length, obj, count_offset);
- codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ Cmp(length, 0);
- __ B(ge, &uncompressed_load);
+ __ Lsrs(length, length, 1u); // LSRS has a 16-bit encoding, TST (immediate) does not.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ B(cs, &uncompressed_load);
__ Ldrb(RegisterFrom(out_loc), MemOperand(temp, RegisterFrom(index), vixl32::LSL, 0));
__ B(&done);
__ Bind(&uncompressed_load);
@@ -4211,7 +4214,7 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
// Mask out compression flag from String's array length.
if (mirror::kUseStringCompression && instruction->IsStringLength()) {
- __ Bic(out, out, 1u << 31);
+ __ Lsr(out, out, 1u);
}
}
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 2f946e4..2782d56 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -151,7 +151,7 @@
}
__ movl(length_loc.AsRegister<Register>(), array_len);
if (mirror::kUseStringCompression) {
- __ andl(length_loc.AsRegister<Register>(), Immediate(INT32_MAX));
+ __ shrl(length_loc.AsRegister<Register>(), Immediate(1));
}
}
x86_codegen->EmitParallelMoves(
@@ -5237,9 +5237,11 @@
// Branch cases into compressed and uncompressed for each index's type.
uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
NearLabel done, not_compressed;
- __ cmpl(Address(obj, count_offset), Immediate(0));
+ __ testl(Address(obj, count_offset), Immediate(1));
codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ j(kGreaterEqual, ¬_compressed);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ j(kNotZero, ¬_compressed);
__ movzxb(out, CodeGeneratorX86::ArrayAddress(obj, index, TIMES_1, data_offset));
__ jmp(&done);
__ Bind(¬_compressed);
@@ -5589,7 +5591,7 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
// Mask out most significant bit in case the array is String's array of char.
if (mirror::kUseStringCompression && instruction->IsStringLength()) {
- __ andl(out, Immediate(INT32_MAX));
+ __ shrl(out, Immediate(1));
}
}
@@ -5648,10 +5650,12 @@
Location array_loc = array_length->GetLocations()->InAt(0);
Address array_len(array_loc.AsRegister<Register>(), len_offset);
if (is_string_compressed_char_at) {
+ // TODO: if index_loc.IsConstant(), compare twice the index (to compensate for
+ // the string compression flag) with the in-memory length and avoid the temporary.
Register length_reg = locations->GetTemp(0).AsRegister<Register>();
__ movl(length_reg, array_len);
codegen_->MaybeRecordImplicitNullCheck(array_length);
- __ andl(length_reg, Immediate(INT32_MAX));
+ __ shrl(length_reg, Immediate(1));
codegen_->GenerateIntCompare(length_reg, index_loc);
} else {
// Checking bounds for general case:
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 232c3b3..a3327e2 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -199,7 +199,7 @@
}
__ movl(length_loc.AsRegister<CpuRegister>(), array_len);
if (mirror::kUseStringCompression) {
- __ andl(length_loc.AsRegister<CpuRegister>(), Immediate(INT32_MAX));
+ __ shrl(length_loc.AsRegister<CpuRegister>(), Immediate(1));
}
}
@@ -4729,9 +4729,11 @@
// Branch cases into compressed and uncompressed for each index's type.
uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
NearLabel done, not_compressed;
- __ cmpl(Address(obj, count_offset), Immediate(0));
+ __ testl(Address(obj, count_offset), Immediate(1));
codegen_->MaybeRecordImplicitNullCheck(instruction);
- __ j(kGreaterEqual, ¬_compressed);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ j(kNotZero, ¬_compressed);
__ movzxb(out, CodeGeneratorX86_64::ArrayAddress(obj, index, TIMES_1, data_offset));
__ jmp(&done);
__ Bind(¬_compressed);
@@ -5063,7 +5065,7 @@
codegen_->MaybeRecordImplicitNullCheck(instruction);
// Mask out most significant bit in case the array is String's array of char.
if (mirror::kUseStringCompression && instruction->IsStringLength()) {
- __ andl(out, Immediate(INT32_MAX));
+ __ shrl(out, Immediate(1));
}
}
@@ -5115,10 +5117,12 @@
Location array_loc = array_length->GetLocations()->InAt(0);
Address array_len(array_loc.AsRegister<CpuRegister>(), len_offset);
if (mirror::kUseStringCompression && instruction->IsStringCharAt()) {
+ // TODO: if index_loc.IsConstant(), compare twice the index (to compensate for
+ // the string compression flag) with the in-memory length and avoid the temporary.
CpuRegister length_reg = CpuRegister(TMP);
__ movl(length_reg, array_len);
codegen_->MaybeRecordImplicitNullCheck(array_length);
- __ andl(length_reg, Immediate(INT32_MAX));
+ __ shrl(length_reg, Immediate(1));
codegen_->GenerateIntCompare(length_reg, index_loc);
} else {
// Checking the bound for general case:
diff --git a/compiler/optimizing/instruction_simplifier_arm64.cc b/compiler/optimizing/instruction_simplifier_arm64.cc
index d0dd650..6d107d5 100644
--- a/compiler/optimizing/instruction_simplifier_arm64.cc
+++ b/compiler/optimizing/instruction_simplifier_arm64.cc
@@ -140,13 +140,6 @@
void InstructionSimplifierArm64Visitor::VisitArrayGet(HArrayGet* instruction) {
size_t data_offset = CodeGenerator::GetArrayDataOffset(instruction);
- // Don't move the array pointer if it is charAt because we need to take the count first.
- // TODO: Implement reading (length + compression) for String compression feature from
- // negative offset (count_offset - data_offset) using LDP and clobbering an extra temporary.
- // Note that "LDR (Immediate)" does not have a "signed offset" encoding.
- if (mirror::kUseStringCompression && instruction->IsStringCharAt()) {
- return;
- }
if (TryExtractArrayAccessAddress(instruction,
instruction->GetArray(),
instruction->GetIndex(),
diff --git a/compiler/optimizing/intrinsics_arm.cc b/compiler/optimizing/intrinsics_arm.cc
index 93a2340..3e6b0af 100644
--- a/compiler/optimizing/intrinsics_arm.cc
+++ b/compiler/optimizing/intrinsics_arm.cc
@@ -1058,7 +1058,6 @@
// Need temporary registers for String compression's feature.
if (mirror::kUseStringCompression) {
locations->AddTemp(Location::RequiresRegister());
- locations->AddTemp(Location::RequiresRegister());
}
locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
}
@@ -1074,10 +1073,9 @@
Register temp0 = locations->GetTemp(0).AsRegister<Register>();
Register temp1 = locations->GetTemp(1).AsRegister<Register>();
Register temp2 = locations->GetTemp(2).AsRegister<Register>();
- Register temp3, temp4;
+ Register temp3;
if (mirror::kUseStringCompression) {
temp3 = locations->GetTemp(3).AsRegister<Register>();
- temp4 = locations->GetTemp(4).AsRegister<Register>();
}
Label loop;
@@ -1104,41 +1102,42 @@
// Reference equality check, return 0 if same reference.
__ subs(out, str, ShifterOperand(arg));
__ b(&end, EQ);
+
if (mirror::kUseStringCompression) {
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ ldr(temp3, Address(str, count_offset));
- __ ldr(temp4, Address(arg, count_offset));
- // Clean out compression flag from lengths.
- __ bic(temp0, temp3, ShifterOperand(0x80000000));
- __ bic(IP, temp4, ShifterOperand(0x80000000));
+ __ ldr(temp2, Address(arg, count_offset));
+ // Extract lengths from the `count` fields.
+ __ Lsr(temp0, temp3, 1u);
+ __ Lsr(temp1, temp2, 1u);
} else {
// Load lengths of this and argument strings.
__ ldr(temp0, Address(str, count_offset));
- __ ldr(IP, Address(arg, count_offset));
+ __ ldr(temp1, Address(arg, count_offset));
}
// out = length diff.
- __ subs(out, temp0, ShifterOperand(IP));
+ __ subs(out, temp0, ShifterOperand(temp1));
// temp0 = min(len(str), len(arg)).
__ it(GT);
- __ mov(temp0, ShifterOperand(IP), GT);
+ __ mov(temp0, ShifterOperand(temp1), GT);
// Shorter string is empty?
__ CompareAndBranchIfZero(temp0, &end);
if (mirror::kUseStringCompression) {
// Check if both strings using same compression style to use this comparison loop.
- __ eors(temp3, temp3, ShifterOperand(temp4));
- __ b(&different_compression, MI);
- }
- // Store offset of string value in preparation for comparison loop.
- __ mov(temp1, ShifterOperand(value_offset));
- if (mirror::kUseStringCompression) {
+ __ eor(temp2, temp2, ShifterOperand(temp3));
+ __ Lsrs(temp2, temp2, 1u);
+ __ b(&different_compression, CS);
// For string compression, calculate the number of bytes to compare (not chars).
// This could in theory exceed INT32_MAX, so treat temp0 as unsigned.
- __ cmp(temp4, ShifterOperand(0));
- __ it(GE);
- __ add(temp0, temp0, ShifterOperand(temp0), GE);
+ __ Lsls(temp3, temp3, 31u); // Extract purely the compression flag.
+ __ it(NE);
+ __ add(temp0, temp0, ShifterOperand(temp0), NE);
}
+ // Store offset of string value in preparation for comparison loop.
+ __ mov(temp1, ShifterOperand(value_offset));
+
// Assertions that must hold in order to compare multiple characters at a time.
CHECK_ALIGNED(value_offset, 8);
static_assert(IsAligned<8>(kObjectAlignment),
@@ -1198,69 +1197,80 @@
// The comparison is unsigned for string compression, otherwise signed.
__ cmp(temp0, ShifterOperand(temp1, LSR, mirror::kUseStringCompression ? 3 : 4));
__ b(&end, mirror::kUseStringCompression ? LS : LE);
+
// Extract the characters and calculate the difference.
- Label uncompressed_string, continue_process;
if (mirror::kUseStringCompression) {
- __ cmp(temp4, ShifterOperand(0));
- __ b(&uncompressed_string, GE);
- __ bic(temp1, temp1, ShifterOperand(0x7));
- __ b(&continue_process);
+ // For compressed strings we need to clear 0x7 from temp1, for uncompressed we need to clear
+ // 0xf. We also need to prepare the character extraction mask `uncompressed ? 0xffffu : 0xffu`.
+ // The compression flag is now in the highest bit of temp3, so let's play some tricks.
+ __ orr(temp3, temp3, ShifterOperand(0xffu << 23)); // uncompressed ? 0xff800000u : 0x7ff80000u
+ __ bic(temp1, temp1, ShifterOperand(temp3, LSR, 31 - 3)); // &= ~(uncompressed ? 0xfu : 0x7u)
+ __ Asr(temp3, temp3, 7u); // uncompressed ? 0xffff0000u : 0xff0000u.
+ __ Lsr(temp2, temp2, temp1); // Extract second character.
+ __ Lsr(temp3, temp3, 16u); // uncompressed ? 0xffffu : 0xffu
+ __ Lsr(out, IP, temp1); // Extract first character.
+ __ and_(temp2, temp2, ShifterOperand(temp3));
+ __ and_(out, out, ShifterOperand(temp3));
+ } else {
+ __ bic(temp1, temp1, ShifterOperand(0xf));
+ __ Lsr(temp2, temp2, temp1);
+ __ Lsr(out, IP, temp1);
+ __ movt(temp2, 0);
+ __ movt(out, 0);
}
- __ Bind(&uncompressed_string);
- __ bic(temp1, temp1, ShifterOperand(0xf));
- __ Bind(&continue_process);
- __ Lsr(temp2, temp2, temp1);
- __ Lsr(IP, IP, temp1);
- Label calculate_difference, uncompressed_string_extract_chars;
- if (mirror::kUseStringCompression) {
- __ cmp(temp4, ShifterOperand(0));
- __ b(&uncompressed_string_extract_chars, GE);
- __ ubfx(temp2, temp2, 0, 8);
- __ ubfx(IP, IP, 0, 8);
- __ b(&calculate_difference);
- }
- __ Bind(&uncompressed_string_extract_chars);
- __ movt(temp2, 0);
- __ movt(IP, 0);
- __ Bind(&calculate_difference);
- __ sub(out, IP, ShifterOperand(temp2));
- __ b(&end);
+ __ sub(out, out, ShifterOperand(temp2));
if (mirror::kUseStringCompression) {
+ __ b(&end);
+ __ Bind(&different_compression);
+
+ // Comparison for different compression style.
const size_t c_char_size = Primitive::ComponentSize(Primitive::kPrimByte);
DCHECK_EQ(c_char_size, 1u);
- Label loop_arg_compressed, loop_this_compressed, find_diff;
- // Comparison for different compression style.
- // This part is when THIS is compressed and ARG is not.
- __ Bind(&different_compression);
- __ add(temp2, str, ShifterOperand(value_offset));
- __ add(temp3, arg, ShifterOperand(value_offset));
- __ cmp(temp4, ShifterOperand(0));
- __ b(&loop_arg_compressed, LT);
- __ Bind(&loop_this_compressed);
- __ ldrb(IP, Address(temp2, c_char_size, Address::PostIndex));
- __ ldrh(temp4, Address(temp3, char_size, Address::PostIndex));
- __ cmp(IP, ShifterOperand(temp4));
- __ b(&find_diff, NE);
- __ subs(temp0, temp0, ShifterOperand(1));
- __ b(&loop_this_compressed, GT);
- __ b(&end);
+ // We want to free up the temp3, currently holding `str.count`, for comparison.
+ // So, we move it to the bottom bit of the iteration count `temp0` which we tnen
+ // need to treat as unsigned. Start by freeing the bit with an ADD and continue
+ // further down by a LSRS+SBC which will flip the meaning of the flag but allow
+ // `subs temp0, #2; bhi different_compression_loop` to serve as the loop condition.
+ __ add(temp0, temp0, ShifterOperand(temp0)); // Unlike LSL, this ADD is always 16-bit.
+ // `temp1` will hold the compressed data pointer, `temp2` the uncompressed data pointer.
+ __ mov(temp1, ShifterOperand(str));
+ __ mov(temp2, ShifterOperand(arg));
+ __ Lsrs(temp3, temp3, 1u); // Continue the move of the compression flag.
+ __ it(CS, kItThen); // Interleave with selection of temp1 and temp2.
+ __ mov(temp1, ShifterOperand(arg), CS); // Preserves flags.
+ __ mov(temp2, ShifterOperand(str), CS); // Preserves flags.
+ __ sbc(temp0, temp0, ShifterOperand(0)); // Complete the move of the compression flag.
- // This part is when THIS is not compressed and ARG is.
- __ Bind(&loop_arg_compressed);
- __ ldrh(IP, Address(temp2, char_size, Address::PostIndex));
- __ ldrb(temp4, Address(temp3, c_char_size, Address::PostIndex));
- __ cmp(IP, ShifterOperand(temp4));
- __ b(&find_diff, NE);
- __ subs(temp0, temp0, ShifterOperand(1));
- __ b(&loop_arg_compressed, GT);
+ // Adjust temp1 and temp2 from string pointers to data pointers.
+ __ add(temp1, temp1, ShifterOperand(value_offset));
+ __ add(temp2, temp2, ShifterOperand(value_offset));
+
+ Label different_compression_loop;
+ Label different_compression_diff;
+
+ // Main loop for different compression.
+ __ Bind(&different_compression_loop);
+ __ ldrb(IP, Address(temp1, c_char_size, Address::PostIndex));
+ __ ldrh(temp3, Address(temp2, char_size, Address::PostIndex));
+ __ cmp(IP, ShifterOperand(temp3));
+ __ b(&different_compression_diff, NE);
+ __ subs(temp0, temp0, ShifterOperand(2));
+ __ b(&different_compression_loop, HI);
__ b(&end);
// Calculate the difference.
- __ Bind(&find_diff);
- __ sub(out, IP, ShifterOperand(temp4));
+ __ Bind(&different_compression_diff);
+ __ sub(out, IP, ShifterOperand(temp3));
+ // Flip the difference if the `arg` is compressed.
+ // `temp0` contains inverted `str` compression flag, i.e the same as `arg` compression flag.
+ __ Lsrs(temp0, temp0, 1u);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ it(CC);
+ __ rsb(out, out, ShifterOperand(0), CC);
}
__ Bind(&end);
@@ -1298,7 +1308,7 @@
Register temp1 = locations->GetTemp(1).AsRegister<Register>();
Register temp2 = locations->GetTemp(2).AsRegister<Register>();
- Label loop, preloop;
+ Label loop;
Label end;
Label return_true;
Label return_false;
@@ -1317,6 +1327,10 @@
__ CompareAndBranchIfZero(arg, &return_false);
}
+ // Reference equality check, return true if same reference.
+ __ cmp(str, ShifterOperand(arg));
+ __ b(&return_true, EQ);
+
if (!optimizations.GetArgumentIsString()) {
// Instanceof check for the argument by comparing class fields.
// All string objects must have the same type since String cannot be subclassed.
@@ -1328,48 +1342,44 @@
__ b(&return_false, NE);
}
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ ldr(temp, Address(str, count_offset));
__ ldr(temp1, Address(arg, count_offset));
- // Check if lengths are equal, return false if they're not.
+ // Check if `count` fields are equal, return false if they're not.
// Also compares the compression style, if differs return false.
__ cmp(temp, ShifterOperand(temp1));
__ b(&return_false, NE);
- // Return true if both strings are empty.
- if (mirror::kUseStringCompression) {
- // Length needs to be masked out first because 0 is treated as compressed.
- __ bic(temp, temp, ShifterOperand(0x80000000));
- }
+ // Return true if both strings are empty. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
__ cbz(temp, &return_true);
- // Reference equality check, return true if same reference.
- __ cmp(str, ShifterOperand(arg));
- __ b(&return_true, EQ);
- // Assertions that must hold in order to compare strings 2 characters at a time.
+ // Assertions that must hold in order to compare strings 4 bytes at a time.
DCHECK_ALIGNED(value_offset, 4);
static_assert(IsAligned<4>(kObjectAlignment), "String data must be aligned for fast compare.");
if (mirror::kUseStringCompression) {
- // If not compressed, directly to fast compare. Else do preprocess on length.
- __ cmp(temp1, ShifterOperand(0));
- __ b(&preloop, GT);
- // Mask out compression flag and adjust length for compressed string (8-bit)
- // as if it is a 16-bit data, new_length = (length + 1) / 2.
- __ add(temp, temp, ShifterOperand(1));
- __ Lsr(temp, temp, 1);
- __ Bind(&preloop);
+ // For string compression, calculate the number of bytes to compare (not chars).
+ // This could in theory exceed INT32_MAX, so treat temp as unsigned.
+ __ Lsrs(temp, temp, 1u); // Extract length and check compression flag.
+ __ it(CS); // If uncompressed,
+ __ add(temp, temp, ShifterOperand(temp), CS); // double the byte count.
}
- // Loop to compare strings 2 characters at a time starting at the front of the string.
- // Ok to do this because strings with an odd length are zero-padded.
+
+ // Store offset of string value in preparation for comparison loop.
__ LoadImmediate(temp1, value_offset);
+
+ // Loop to compare strings 4 bytes at a time starting at the front of the string.
+ // Ok to do this because strings are zero-padded to kObjectAlignment.
__ Bind(&loop);
__ ldr(out, Address(str, temp1));
__ ldr(temp2, Address(arg, temp1));
+ __ add(temp1, temp1, ShifterOperand(sizeof(uint32_t)));
__ cmp(out, ShifterOperand(temp2));
__ b(&return_false, NE);
- __ add(temp1, temp1, ShifterOperand(sizeof(uint32_t)));
- __ subs(temp, temp, ShifterOperand(sizeof(uint32_t) / sizeof(uint16_t)));
- __ b(&loop, GT);
+ // With string compression, we have compared 4 bytes, otherwise 2 chars.
+ __ subs(temp, temp, ShifterOperand(mirror::kUseStringCompression ? 4 : 2));
+ __ b(&loop, HI);
// Return true and exit the function.
// If loop does not result in returning false, we return true.
@@ -2477,8 +2487,8 @@
const uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
// String's length.
__ ldr(IP, Address(srcObj, count_offset));
- __ cmp(IP, ShifterOperand(0));
- __ b(&compressed_string_preloop, LT);
+ __ tst(IP, ShifterOperand(1));
+ __ b(&compressed_string_preloop, EQ);
}
__ add(src_ptr, src_ptr, ShifterOperand(srcBegin, LSL, 1));
@@ -2513,9 +2523,10 @@
__ subs(num_chr, num_chr, ShifterOperand(1));
__ strh(IP, Address(dst_ptr, char_size, Address::PostIndex));
__ b(&remainder, GT);
- __ b(&done);
if (mirror::kUseStringCompression) {
+ __ b(&done);
+
const size_t c_char_size = Primitive::ComponentSize(Primitive::kPrimByte);
DCHECK_EQ(c_char_size, 1u);
// Copy loop for compressed src, copying 1 character (8-bit) to (16-bit) at a time.
diff --git a/compiler/optimizing/intrinsics_arm64.cc b/compiler/optimizing/intrinsics_arm64.cc
index 47e6d96..9b17931 100644
--- a/compiler/optimizing/intrinsics_arm64.cc
+++ b/compiler/optimizing/intrinsics_arm64.cc
@@ -1243,7 +1243,6 @@
// Need temporary registers for String compression's feature.
if (mirror::kUseStringCompression) {
locations->AddTemp(Location::RequiresRegister());
- locations->AddTemp(Location::RequiresRegister());
}
locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
}
@@ -1261,10 +1260,9 @@
Register temp0 = WRegisterFrom(locations->GetTemp(0));
Register temp1 = WRegisterFrom(locations->GetTemp(1));
Register temp2 = WRegisterFrom(locations->GetTemp(2));
- Register temp3, temp5;
+ Register temp3;
if (mirror::kUseStringCompression) {
temp3 = WRegisterFrom(locations->GetTemp(3));
- temp5 = WRegisterFrom(locations->GetTemp(4));
}
vixl::aarch64::Label loop;
@@ -1291,68 +1289,65 @@
// Reference equality check, return 0 if same reference.
__ Subs(out, str, arg);
__ B(&end, eq);
+
if (mirror::kUseStringCompression) {
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ Ldr(temp3, HeapOperand(str, count_offset));
- __ Ldr(temp5, HeapOperand(arg, count_offset));
+ __ Ldr(temp2, HeapOperand(arg, count_offset));
// Clean out compression flag from lengths.
- __ Bic(temp0, temp3, Operand(static_cast<int32_t>(0x80000000)));
- __ Bic(temp1, temp5, Operand(static_cast<int32_t>(0x80000000)));
+ __ Lsr(temp0, temp3, 1u);
+ __ Lsr(temp1, temp2, 1u);
} else {
// Load lengths of this and argument strings.
__ Ldr(temp0, HeapOperand(str, count_offset));
__ Ldr(temp1, HeapOperand(arg, count_offset));
}
- // Return zero if both strings are empty.
- __ Orr(out, temp0, temp1);
- __ Cbz(out, &end);
// out = length diff.
__ Subs(out, temp0, temp1);
- // temp2 = min(len(str), len(arg)).
- __ Csel(temp2, temp1, temp0, ge);
+ // temp0 = min(len(str), len(arg)).
+ __ Csel(temp0, temp1, temp0, ge);
// Shorter string is empty?
- __ Cbz(temp2, &end);
+ __ Cbz(temp0, &end);
if (mirror::kUseStringCompression) {
// Check if both strings using same compression style to use this comparison loop.
- __ Eor(temp3.W(), temp3, Operand(temp5));
- __ Tbnz(temp3.W(), kWRegSize - 1, &different_compression);
+ __ Eor(temp2, temp2, Operand(temp3));
+ // Interleave with compression flag extraction which is needed for both paths
+ // and also set flags which is needed only for the different compressions path.
+ __ Ands(temp3.W(), temp3.W(), Operand(1));
+ __ Tbnz(temp2, 0, &different_compression); // Does not use flags.
}
// Store offset of string value in preparation for comparison loop.
__ Mov(temp1, value_offset);
if (mirror::kUseStringCompression) {
// For string compression, calculate the number of bytes to compare (not chars).
- // This could be in theory exceed INT32_MAX, so treat temp2 as unsigned.
- vixl::aarch64::Label let_it_signed;
- __ Cmp(temp5, Operand(0));
- __ B(lt, &let_it_signed);
- __ Add(temp2, temp2, Operand(temp2));
- __ Bind(&let_it_signed);
+ // This could in theory exceed INT32_MAX, so treat temp0 as unsigned.
+ __ Lsl(temp0, temp0, temp3);
}
UseScratchRegisterScope scratch_scope(masm);
Register temp4 = scratch_scope.AcquireX();
- // Assertions that must hold in order to compare strings 4 characters at a time.
+ // Assertions that must hold in order to compare strings 8 bytes at a time.
DCHECK_ALIGNED(value_offset, 8);
static_assert(IsAligned<8>(kObjectAlignment), "String of odd length is not zero padded");
const size_t char_size = Primitive::ComponentSize(Primitive::kPrimChar);
DCHECK_EQ(char_size, 2u);
- // Promote temp0 to an X reg, ready for LDR.
- temp0 = temp0.X();
+ // Promote temp2 to an X reg, ready for LDR.
+ temp2 = temp2.X();
// Loop to compare 4x16-bit characters at a time (ok because of string data alignment).
__ Bind(&loop);
__ Ldr(temp4, MemOperand(str.X(), temp1.X()));
- __ Ldr(temp0, MemOperand(arg.X(), temp1.X()));
- __ Cmp(temp4, temp0);
+ __ Ldr(temp2, MemOperand(arg.X(), temp1.X()));
+ __ Cmp(temp4, temp2);
__ B(ne, &find_char_diff);
__ Add(temp1, temp1, char_size * 4);
// With string compression, we have compared 8 bytes, otherwise 4 chars.
- __ Subs(temp2, temp2, (mirror::kUseStringCompression) ? 8 : 4);
- __ B(hi, &loop);
+ __ Subs(temp0, temp0, (mirror::kUseStringCompression) ? 8 : 4);
+ __ B(&loop, hi);
__ B(&end);
// Promote temp1 to an X reg, ready for EOR.
@@ -1361,78 +1356,85 @@
// Find the single character difference.
__ Bind(&find_char_diff);
// Get the bit position of the first character that differs.
- __ Eor(temp1, temp0, temp4);
+ __ Eor(temp1, temp2, temp4);
__ Rbit(temp1, temp1);
__ Clz(temp1, temp1);
+
// If the number of chars remaining <= the index where the difference occurs (0-3), then
// the difference occurs outside the remaining string data, so just return length diff (out).
// Unlike ARM, we're doing the comparison in one go here, without the subtraction at the
// find_char_diff_2nd_cmp path, so it doesn't matter whether the comparison is signed or
// unsigned when string compression is disabled.
// When it's enabled, the comparison must be unsigned.
- __ Cmp(temp2, Operand(temp1.W(), LSR, (mirror::kUseStringCompression) ? 3 : 4));
+ __ Cmp(temp0, Operand(temp1.W(), LSR, (mirror::kUseStringCompression) ? 3 : 4));
__ B(ls, &end);
+
// Extract the characters and calculate the difference.
- vixl::aarch64::Label uncompressed_string, continue_process;
if (mirror:: kUseStringCompression) {
- __ Tbz(temp5, kWRegSize - 1, &uncompressed_string);
__ Bic(temp1, temp1, 0x7);
- __ B(&continue_process);
+ __ Bic(temp1, temp1, Operand(temp3.X(), LSL, 3u));
+ } else {
+ __ Bic(temp1, temp1, 0xf);
}
- __ Bind(&uncompressed_string);
- __ Bic(temp1, temp1, 0xf);
- __ Bind(&continue_process);
-
- __ Lsr(temp0, temp0, temp1);
+ __ Lsr(temp2, temp2, temp1);
__ Lsr(temp4, temp4, temp1);
- vixl::aarch64::Label uncompressed_string_extract_chars;
if (mirror::kUseStringCompression) {
- __ Tbz(temp5, kWRegSize - 1, &uncompressed_string_extract_chars);
- __ And(temp4, temp4, 0xff);
- __ Sub(out, temp4.W(), Operand(temp0.W(), UXTB));
- __ B(&end);
+ // Prioritize the case of compressed strings and calculate such result first.
+ __ Uxtb(temp1, temp4);
+ __ Sub(out, temp1.W(), Operand(temp2.W(), UXTB));
+ __ Tbz(temp3, 0u, &end); // If actually compressed, we're done.
}
- __ Bind(&uncompressed_string_extract_chars);
- __ And(temp4, temp4, 0xffff);
- __ Sub(out, temp4.W(), Operand(temp0.W(), UXTH));
- __ B(&end);
+ __ Uxth(temp4, temp4);
+ __ Sub(out, temp4.W(), Operand(temp2.W(), UXTH));
if (mirror::kUseStringCompression) {
- vixl::aarch64::Label loop_this_compressed, loop_arg_compressed, find_diff;
+ __ B(&end);
+ __ Bind(&different_compression);
+
+ // Comparison for different compression style.
const size_t c_char_size = Primitive::ComponentSize(Primitive::kPrimByte);
DCHECK_EQ(c_char_size, 1u);
- temp0 = temp0.W();
temp1 = temp1.W();
- // Comparison for different compression style.
- // This part is when THIS is compressed and ARG is not.
- __ Bind(&different_compression);
- __ Add(temp0, str, Operand(value_offset));
- __ Add(temp1, arg, Operand(value_offset));
- __ Cmp(temp5, Operand(0));
- __ B(lt, &loop_arg_compressed);
+ temp2 = temp2.W();
+ temp4 = temp4.W();
- __ Bind(&loop_this_compressed);
- __ Ldrb(temp3, MemOperand(temp0.X(), c_char_size, PostIndex));
- __ Ldrh(temp5, MemOperand(temp1.X(), char_size, PostIndex));
- __ Cmp(temp3, Operand(temp5));
- __ B(ne, &find_diff);
- __ Subs(temp2, temp2, 1);
- __ B(gt, &loop_this_compressed);
- __ B(&end);
+ // `temp1` will hold the compressed data pointer, `temp2` the uncompressed data pointer.
+ // Note that flags have been set by the `str` compression flag extraction to `temp3`
+ // before branching to the `different_compression` label.
+ __ Csel(temp1, str, arg, eq); // Pointer to the compressed string.
+ __ Csel(temp2, str, arg, ne); // Pointer to the uncompressed string.
- // This part is when THIS is not compressed and ARG is.
- __ Bind(&loop_arg_compressed);
- __ Ldrh(temp3, MemOperand(temp0.X(), char_size, PostIndex));
- __ Ldrb(temp5, MemOperand(temp1.X(), c_char_size, PostIndex));
- __ Cmp(temp3, Operand(temp5));
- __ B(ne, &find_diff);
- __ Subs(temp2, temp2, 1);
- __ B(gt, &loop_arg_compressed);
+ // We want to free up the temp3, currently holding `str` compression flag, for comparison.
+ // So, we move it to the bottom bit of the iteration count `temp0` which we then need to treat
+ // as unsigned. Start by freeing the bit with a LSL and continue further down by a SUB which
+ // will allow `subs temp0, #2; bhi different_compression_loop` to serve as the loop condition.
+ __ Lsl(temp0, temp0, 1u);
+
+ // Adjust temp1 and temp2 from string pointers to data pointers.
+ __ Add(temp1, temp1, Operand(value_offset));
+ __ Add(temp2, temp2, Operand(value_offset));
+
+ // Complete the move of the compression flag.
+ __ Sub(temp0, temp0, Operand(temp3));
+
+ vixl::aarch64::Label different_compression_loop;
+ vixl::aarch64::Label different_compression_diff;
+
+ __ Bind(&different_compression_loop);
+ __ Ldrb(temp4, MemOperand(temp1.X(), c_char_size, PostIndex));
+ __ Ldrh(temp3, MemOperand(temp2.X(), char_size, PostIndex));
+ __ Subs(temp4, temp4, Operand(temp3));
+ __ B(&different_compression_diff, ne);
+ __ Subs(temp0, temp0, 2);
+ __ B(&different_compression_loop, hi);
__ B(&end);
// Calculate the difference.
- __ Bind(&find_diff);
- __ Sub(out, temp3.W(), Operand(temp5.W(), UXTH));
+ __ Bind(&different_compression_diff);
+ __ Tst(temp0, Operand(1));
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ Cneg(out, temp4, ne);
}
__ Bind(&end);
@@ -1468,7 +1470,7 @@
Register temp1 = WRegisterFrom(locations->GetTemp(0));
Register temp2 = WRegisterFrom(locations->GetTemp(1));
- vixl::aarch64::Label loop, preloop;
+ vixl::aarch64::Label loop;
vixl::aarch64::Label end;
vixl::aarch64::Label return_true;
vixl::aarch64::Label return_false;
@@ -1502,49 +1504,46 @@
__ B(&return_false, ne);
}
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ Ldr(temp, MemOperand(str.X(), count_offset));
__ Ldr(temp1, MemOperand(arg.X(), count_offset));
- // Check if lengths are equal, return false if they're not.
+ // Check if `count` fields are equal, return false if they're not.
// Also compares the compression style, if differs return false.
__ Cmp(temp, temp1);
__ B(&return_false, ne);
- // Return true if both strings are empty.
- if (mirror::kUseStringCompression) {
- // Length needs to be masked out first because 0 is treated as compressed.
- __ Bic(temp, temp, Operand(static_cast<int32_t>(0x80000000)));
- }
+ // Return true if both strings are empty. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
__ Cbz(temp, &return_true);
- // Assertions that must hold in order to compare strings 4 characters at a time.
+ // Assertions that must hold in order to compare strings 8 bytes at a time.
DCHECK_ALIGNED(value_offset, 8);
static_assert(IsAligned<8>(kObjectAlignment), "String of odd length is not zero padded");
if (mirror::kUseStringCompression) {
- // If not compressed, directly to fast compare. Else do preprocess on length.
- __ Cmp(temp1, Operand(0));
- __ B(&preloop, gt);
- // Mask out compression flag and adjust length for compressed string (8-bit)
- // as if it is a 16-bit data, new_length = (length + 1) / 2
- __ Add(temp, temp, 1);
- __ Lsr(temp, temp, 1);
+ // For string compression, calculate the number of bytes to compare (not chars).
+ // This could in theory exceed INT32_MAX, so treat temp as unsigned.
+ __ Lsr(temp, temp, 1u); // Extract length.
+ __ And(temp1, temp1, Operand(1)); // Extract compression flag.
+ __ Lsl(temp, temp, temp1); // Calculate number of bytes to compare.
}
+ // Store offset of string value in preparation for comparison loop
+ __ Mov(temp1, value_offset);
+
temp1 = temp1.X();
temp2 = temp2.X();
- // Loop to compare strings 4 characters at a time starting at the beginning of the string.
- // Ok to do this because strings are zero-padded to be 8-byte aligned.
- // Store offset of string value in preparation for comparison loop
- __ Bind(&preloop);
- __ Mov(temp1, value_offset);
+ // Loop to compare strings 8 bytes at a time starting at the front of the string.
+ // Ok to do this because strings are zero-padded to kObjectAlignment.
__ Bind(&loop);
__ Ldr(out, MemOperand(str.X(), temp1));
__ Ldr(temp2, MemOperand(arg.X(), temp1));
__ Add(temp1, temp1, Operand(sizeof(uint64_t)));
__ Cmp(out, temp2);
__ B(&return_false, ne);
- __ Sub(temp, temp, Operand(4), SetFlags);
- __ B(&loop, gt);
+ // With string compression, we have compared 8 bytes, otherwise 4 chars.
+ __ Sub(temp, temp, Operand(mirror::kUseStringCompression ? 8 : 4), SetFlags);
+ __ B(&loop, hi);
// Return true and exit the function.
// If loop does not result in returning false, we return true.
@@ -1900,10 +1899,6 @@
locations->AddTemp(Location::RequiresRegister());
locations->AddTemp(Location::RequiresRegister());
locations->AddTemp(Location::RequiresRegister());
- // Need temporary register for String compression feature.
- if (mirror::kUseStringCompression) {
- locations->AddTemp(Location::RequiresRegister());
- }
}
void IntrinsicCodeGeneratorARM64::VisitStringGetCharsNoCheck(HInvoke* invoke) {
@@ -1931,10 +1926,6 @@
Register src_ptr = XRegisterFrom(locations->GetTemp(0));
Register num_chr = XRegisterFrom(locations->GetTemp(1));
Register tmp1 = XRegisterFrom(locations->GetTemp(2));
- Register tmp3;
- if (mirror::kUseStringCompression) {
- tmp3 = WRegisterFrom(locations->GetTemp(3));
- }
UseScratchRegisterScope temps(masm);
Register dst_ptr = temps.AcquireX();
@@ -1957,8 +1948,8 @@
// Location of count in string.
const uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
// String's length.
- __ Ldr(tmp3, MemOperand(srcObj, count_offset));
- __ Tbnz(tmp3, kWRegSize - 1, &compressed_string_preloop);
+ __ Ldr(tmp2, MemOperand(srcObj, count_offset));
+ __ Tbz(tmp2, 0, &compressed_string_preloop);
}
__ Add(src_ptr, src_ptr, Operand(srcBegin, LSL, 1));
diff --git a/compiler/optimizing/intrinsics_arm_vixl.cc b/compiler/optimizing/intrinsics_arm_vixl.cc
index 6ff0ca4..1450b5a 100644
--- a/compiler/optimizing/intrinsics_arm_vixl.cc
+++ b/compiler/optimizing/intrinsics_arm_vixl.cc
@@ -1120,7 +1120,6 @@
// Need temporary registers for String compression's feature.
if (mirror::kUseStringCompression) {
locations->AddTemp(Location::RequiresRegister());
- locations->AddTemp(Location::RequiresRegister());
}
locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
}
@@ -1136,10 +1135,9 @@
vixl32::Register temp0 = RegisterFrom(locations->GetTemp(0));
vixl32::Register temp1 = RegisterFrom(locations->GetTemp(1));
vixl32::Register temp2 = RegisterFrom(locations->GetTemp(2));
- vixl32::Register temp3, temp4;
+ vixl32::Register temp3;
if (mirror::kUseStringCompression) {
temp3 = RegisterFrom(locations->GetTemp(3));
- temp4 = RegisterFrom(locations->GetTemp(4));
}
vixl32::Label loop;
@@ -1167,23 +1165,20 @@
__ Subs(out, str, arg);
__ B(eq, &end);
- UseScratchRegisterScope temps(assembler->GetVIXLAssembler());
- vixl32::Register temp_reg = temps.Acquire();
-
if (mirror::kUseStringCompression) {
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ Ldr(temp3, MemOperand(str, count_offset));
- __ Ldr(temp4, MemOperand(arg, count_offset));
- // Clean out compression flag from lengths.
- __ Bic(temp0, temp3, 0x80000000);
- __ Bic(temp_reg, temp4, 0x80000000);
+ __ Ldr(temp2, MemOperand(arg, count_offset));
+ // Extract lengths from the `count` fields.
+ __ Lsr(temp0, temp3, 1u);
+ __ Lsr(temp1, temp2, 1u);
} else {
// Load lengths of this and argument strings.
__ Ldr(temp0, MemOperand(str, count_offset));
- __ Ldr(temp_reg, MemOperand(arg, count_offset));
+ __ Ldr(temp1, MemOperand(arg, count_offset));
}
// out = length diff.
- __ Subs(out, temp0, temp_reg);
+ __ Subs(out, temp0, temp1);
// temp0 = min(len(str), len(arg)).
{
@@ -1192,33 +1187,32 @@
CodeBufferCheckScope::kMaximumSize);
__ it(gt);
- __ mov(gt, temp0, temp_reg);
+ __ mov(gt, temp0, temp1);
}
- temps.Release(temp_reg);
// Shorter string is empty?
__ Cbz(temp0, &end);
if (mirror::kUseStringCompression) {
// Check if both strings using same compression style to use this comparison loop.
- __ Eors(temp3, temp3, temp4);
- __ B(mi, &different_compression);
- }
- // Store offset of string value in preparation for comparison loop.
- __ Mov(temp1, value_offset);
- if (mirror::kUseStringCompression) {
+ __ Eors(temp2, temp2, temp3);
+ __ Lsrs(temp2, temp2, 1u);
+ __ B(cs, &different_compression);
// For string compression, calculate the number of bytes to compare (not chars).
// This could in theory exceed INT32_MAX, so treat temp0 as unsigned.
- __ Cmp(temp4, 0);
+ __ Lsls(temp3, temp3, 31u); // Extract purely the compression flag.
AssemblerAccurateScope aas(assembler->GetVIXLAssembler(),
2 * kMaxInstructionSizeInBytes,
CodeBufferCheckScope::kMaximumSize);
- __ it(ge);
- __ add(ge, temp0, temp0, temp0);
+ __ it(ne);
+ __ add(ne, temp0, temp0, temp0);
}
+ // Store offset of string value in preparation for comparison loop.
+ __ Mov(temp1, value_offset);
+
// Assertions that must hold in order to compare multiple characters at a time.
CHECK_ALIGNED(value_offset, 8);
static_assert(IsAligned<8>(kObjectAlignment),
@@ -1227,10 +1221,12 @@
const size_t char_size = Primitive::ComponentSize(Primitive::kPrimChar);
DCHECK_EQ(char_size, 2u);
+ UseScratchRegisterScope temps(assembler->GetVIXLAssembler());
+
vixl32::Label find_char_diff_2nd_cmp;
// Unrolled loop comparing 4x16-bit chars per iteration (ok because of string data alignment).
__ Bind(&loop);
- temp_reg = temps.Acquire();
+ vixl32::Register temp_reg = temps.Acquire();
__ Ldr(temp_reg, MemOperand(str, temp1));
__ Ldr(temp2, MemOperand(arg, temp1));
__ Cmp(temp_reg, temp2);
@@ -1279,72 +1275,92 @@
// The comparison is unsigned for string compression, otherwise signed.
__ Cmp(temp0, Operand(temp1, vixl32::LSR, (mirror::kUseStringCompression ? 3 : 4)));
__ B((mirror::kUseStringCompression ? ls : le), &end);
+
// Extract the characters and calculate the difference.
- vixl32::Label uncompressed_string, continue_process;
if (mirror::kUseStringCompression) {
- __ Cmp(temp4, 0);
- __ B(ge, &uncompressed_string);
- __ Bic(temp1, temp1, 0x7);
- __ B(&continue_process);
+ // For compressed strings we need to clear 0x7 from temp1, for uncompressed we need to clear
+ // 0xf. We also need to prepare the character extraction mask `uncompressed ? 0xffffu : 0xffu`.
+ // The compression flag is now in the highest bit of temp3, so let's play some tricks.
+ __ orr(temp3, temp3, 0xffu << 23); // uncompressed ? 0xff800000u : 0x7ff80000u
+ __ bic(temp1, temp1, Operand(temp3, vixl32::LSR, 31 - 3)); // &= ~(uncompressed ? 0xfu : 0x7u)
+ __ Asr(temp3, temp3, 7u); // uncompressed ? 0xffff0000u : 0xff0000u.
+ __ Lsr(temp2, temp2, temp1); // Extract second character.
+ __ Lsr(temp3, temp3, 16u); // uncompressed ? 0xffffu : 0xffu
+ __ Lsr(out, temp_reg, temp1); // Extract first character.
+ __ and_(temp2, temp2, temp3);
+ __ and_(out, out, temp3);
+ } else {
+ __ bic(temp1, temp1, 0xf);
+ __ Lsr(temp2, temp2, temp1);
+ __ Lsr(out, temp_reg, temp1);
+ __ movt(temp2, 0);
+ __ movt(out, 0);
}
- __ Bind(&uncompressed_string);
- __ Bic(temp1, temp1, 0xf);
- __ Bind(&continue_process);
- __ Lsr(temp2, temp2, temp1);
- __ Lsr(temp_reg, temp_reg, temp1);
- vixl32::Label calculate_difference, uncompressed_string_extract_chars;
- if (mirror::kUseStringCompression) {
- __ Cmp(temp4, 0);
- __ B(ge, &uncompressed_string_extract_chars);
- __ Ubfx(temp2, temp2, 0, 8);
- __ Ubfx(temp_reg, temp_reg, 0, 8);
- __ B(&calculate_difference);
- }
- __ Bind(&uncompressed_string_extract_chars);
- __ Movt(temp2, 0);
- __ Movt(temp_reg, 0);
- __ Bind(&calculate_difference);
- __ Sub(out, temp_reg, temp2);
+ __ Sub(out, out, temp2);
temps.Release(temp_reg);
- __ B(&end);
if (mirror::kUseStringCompression) {
+ __ B(&end);
+ __ Bind(&different_compression);
+
+ // Comparison for different compression style.
const size_t c_char_size = Primitive::ComponentSize(Primitive::kPrimByte);
DCHECK_EQ(c_char_size, 1u);
- vixl32::Label loop_arg_compressed, loop_this_compressed, find_diff;
- // Comparison for different compression style.
- // This part is when THIS is compressed and ARG is not.
- __ Bind(&different_compression);
- __ Add(temp2, str, value_offset);
- __ Add(temp3, arg, value_offset);
- __ Cmp(temp4, 0);
- __ B(lt, &loop_arg_compressed);
- __ Bind(&loop_this_compressed);
+ // We want to free up the temp3, currently holding `str.count`, for comparison.
+ // So, we move it to the bottom bit of the iteration count `temp0` which we tnen
+ // need to treat as unsigned. Start by freeing the bit with an ADD and continue
+ // further down by a LSRS+SBC which will flip the meaning of the flag but allow
+ // `subs temp0, #2; bhi different_compression_loop` to serve as the loop condition.
+ __ add(temp0, temp0, temp0); // Unlike LSL, this ADD is always 16-bit.
+ // `temp1` will hold the compressed data pointer, `temp2` the uncompressed data pointer.
+ __ mov(temp1, str);
+ __ mov(temp2, arg);
+ __ Lsrs(temp3, temp3, 1u); // Continue the move of the compression flag.
+ {
+ AssemblerAccurateScope aas(assembler->GetVIXLAssembler(),
+ 3 * kMaxInstructionSizeInBytes,
+ CodeBufferCheckScope::kMaximumSize);
+ __ itt(cs); // Interleave with selection of temp1 and temp2.
+ __ mov(cs, temp1, arg); // Preserves flags.
+ __ mov(cs, temp2, str); // Preserves flags.
+ }
+ __ sbc(temp0, temp0, 0); // Complete the move of the compression flag.
+
+ // Adjust temp1 and temp2 from string pointers to data pointers.
+ __ add(temp1, temp1, value_offset);
+ __ add(temp2, temp2, value_offset);
+
+ vixl32::Label different_compression_loop;
+ vixl32::Label different_compression_diff;
+
+ // Main loop for different compression.
temp_reg = temps.Acquire();
- __ Ldrb(temp_reg, MemOperand(temp2, c_char_size, PostIndex));
- __ Ldrh(temp4, MemOperand(temp3, char_size, PostIndex));
- __ Cmp(temp_reg, temp4);
- __ B(ne, &find_diff);
- __ Subs(temp0, temp0, 1);
- __ B(gt, &loop_this_compressed);
- __ B(&end);
-
- // This part is when THIS is not compressed and ARG is.
- __ Bind(&loop_arg_compressed);
- __ Ldrh(temp_reg, MemOperand(temp2, char_size, PostIndex));
- __ Ldrb(temp4, MemOperand(temp3, c_char_size, PostIndex));
- __ Cmp(temp_reg, temp4);
- __ B(ne, &find_diff);
- __ Subs(temp0, temp0, 1);
- __ B(gt, &loop_arg_compressed);
+ __ Bind(&different_compression_loop);
+ __ Ldrb(temp_reg, MemOperand(temp1, c_char_size, PostIndex));
+ __ Ldrh(temp3, MemOperand(temp2, char_size, PostIndex));
+ __ cmp(temp_reg, temp3);
+ __ B(ne, &different_compression_diff);
+ __ Subs(temp0, temp0, 2);
+ __ B(hi, &different_compression_loop);
__ B(&end);
// Calculate the difference.
- __ Bind(&find_diff);
- __ Sub(out, temp_reg, temp4);
+ __ Bind(&different_compression_diff);
+ __ Sub(out, temp_reg, temp3);
temps.Release(temp_reg);
+ // Flip the difference if the `arg` is compressed.
+ // `temp0` contains inverted `str` compression flag, i.e the same as `arg` compression flag.
+ __ Lsrs(temp0, temp0, 1u);
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+
+ AssemblerAccurateScope aas(assembler->GetVIXLAssembler(),
+ 2 * kMaxInstructionSizeInBytes,
+ CodeBufferCheckScope::kMaximumSize);
+ __ it(cc);
+ __ rsb(cc, out, out, 0);
}
__ Bind(&end);
@@ -1382,7 +1398,7 @@
vixl32::Register temp1 = RegisterFrom(locations->GetTemp(1));
vixl32::Register temp2 = RegisterFrom(locations->GetTemp(2));
- vixl32::Label loop, preloop;
+ vixl32::Label loop;
vixl32::Label end;
vixl32::Label return_true;
vixl32::Label return_false;
@@ -1401,6 +1417,10 @@
__ Cbz(arg, &return_false);
}
+ // Reference equality check, return true if same reference.
+ __ Cmp(str, arg);
+ __ B(eq, &return_true);
+
if (!optimizations.GetArgumentIsString()) {
// Instanceof check for the argument by comparing class fields.
// All string objects must have the same type since String cannot be subclassed.
@@ -1412,48 +1432,47 @@
__ B(ne, &return_false);
}
- // Load lengths of this and argument strings.
+ // Load `count` fields of this and argument strings.
__ Ldr(temp, MemOperand(str, count_offset));
__ Ldr(temp1, MemOperand(arg, count_offset));
- // Check if lengths are equal, return false if they're not.
+ // Check if `count` fields are equal, return false if they're not.
// Also compares the compression style, if differs return false.
__ Cmp(temp, temp1);
__ B(ne, &return_false);
- // Return true if both strings are empty.
- if (mirror::kUseStringCompression) {
- // Length needs to be masked out first because 0 is treated as compressed.
- __ Bic(temp, temp, 0x80000000);
- }
+ // Return true if both strings are empty. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
__ Cbz(temp, &return_true);
- // Reference equality check, return true if same reference.
- __ Cmp(str, arg);
- __ B(eq, &return_true);
- // Assertions that must hold in order to compare strings 2 characters at a time.
+ // Assertions that must hold in order to compare strings 4 bytes at a time.
DCHECK_ALIGNED(value_offset, 4);
static_assert(IsAligned<4>(kObjectAlignment), "String data must be aligned for fast compare.");
if (mirror::kUseStringCompression) {
- // If not compressed, directly to fast compare. Else do preprocess on length.
- __ Cmp(temp1, 0);
- __ B(gt, &preloop);
- // Mask out compression flag and adjust length for compressed string (8-bit)
- // as if it is a 16-bit data, new_length = (length + 1) / 2.
- __ Add(temp, temp, 1);
- __ Lsr(temp, temp, 1);
- __ Bind(&preloop);
+ // For string compression, calculate the number of bytes to compare (not chars).
+ // This could in theory exceed INT32_MAX, so treat temp as unsigned.
+ __ Lsrs(temp, temp, 1u); // Extract length and check compression flag.
+ AssemblerAccurateScope aas(assembler->GetVIXLAssembler(),
+ 2 * kMaxInstructionSizeInBytes,
+ CodeBufferCheckScope::kMaximumSize);
+ __ it(cs); // If uncompressed,
+ __ add(cs, temp, temp, temp); // double the byte count.
}
- // Loop to compare strings 2 characters at a time starting at the front of the string.
- // Ok to do this because strings with an odd length are zero-padded.
+
+ // Store offset of string value in preparation for comparison loop.
__ Mov(temp1, value_offset);
+
+ // Loop to compare strings 4 bytes at a time starting at the front of the string.
+ // Ok to do this because strings are zero-padded to kObjectAlignment.
__ Bind(&loop);
__ Ldr(out, MemOperand(str, temp1));
__ Ldr(temp2, MemOperand(arg, temp1));
+ __ Add(temp1, temp1, sizeof(uint32_t));
__ Cmp(out, temp2);
__ B(ne, &return_false);
- __ Add(temp1, temp1, sizeof(uint32_t));
- __ Subs(temp, temp, sizeof(uint32_t) / sizeof(uint16_t));
- __ B(gt, &loop);
+ // With string compression, we have compared 4 bytes, otherwise 2 chars.
+ __ Subs(temp, temp, mirror::kUseStringCompression ? 4 : 2);
+ __ B(hi, &loop);
// Return true and exit the function.
// If loop does not result in returning false, we return true.
@@ -2547,9 +2566,9 @@
temp = temps.Acquire();
// String's length.
__ Ldr(temp, MemOperand(srcObj, count_offset));
- __ Cmp(temp, 0);
+ __ Tst(temp, 1);
temps.Release(temp);
- __ B(lt, &compressed_string_preloop);
+ __ B(eq, &compressed_string_preloop);
}
__ Add(src_ptr, src_ptr, Operand(srcBegin, vixl32::LSL, 1));
@@ -2588,9 +2607,10 @@
__ Strh(temp, MemOperand(dst_ptr, char_size, PostIndex));
temps.Release(temp);
__ B(gt, &remainder);
- __ B(&done);
if (mirror::kUseStringCompression) {
+ __ B(&done);
+
const size_t c_char_size = Primitive::ComponentSize(Primitive::kPrimByte);
DCHECK_EQ(c_char_size, 1u);
// Copy loop for compressed src, copying 1 character (8-bit) to (16-bit) at a time.
diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 43682c5..80b4df6 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -1408,21 +1408,22 @@
// compression style is decided on alloc.
__ cmpl(ecx, Address(arg, count_offset));
__ j(kNotEqual, &return_false);
+ // Return true if strings are empty. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ jecxz(&return_true);
if (mirror::kUseStringCompression) {
NearLabel string_uncompressed;
- // Differ cases into both compressed or both uncompressed. Different compression style
- // is cut above.
- __ cmpl(ecx, Immediate(0));
- __ j(kGreaterEqual, &string_uncompressed);
+ // Extract length and differentiate between both compressed or both uncompressed.
+ // Different compression style is cut above.
+ __ shrl(ecx, Immediate(1));
+ __ j(kCarrySet, &string_uncompressed);
// Divide string length by 2, rounding up, and continue as if uncompressed.
- // Merge clearing the compression flag (+0x80000000) with +1 for rounding.
- __ addl(ecx, Immediate(0x80000001));
+ __ addl(ecx, Immediate(1));
__ shrl(ecx, Immediate(1));
__ Bind(&string_uncompressed);
}
- // Return true if strings are empty.
- __ jecxz(&return_true);
// Load starting addresses of string values into ESI/EDI as required for repe_cmpsl instruction.
__ leal(esi, Address(str, value_offset));
__ leal(edi, Address(arg, value_offset));
@@ -1535,21 +1536,24 @@
// Location of count within the String object.
int32_t count_offset = mirror::String::CountOffset().Int32Value();
- // Load string length, i.e., the count field of the string.
+ // Load the count field of the string containing the length and compression flag.
__ movl(string_length, Address(string_obj, count_offset));
- if (mirror::kUseStringCompression) {
- string_length_flagged = locations->GetTemp(2).AsRegister<Register>();
- __ movl(string_length_flagged, string_length);
- // Mask out first bit used as compression flag.
- __ andl(string_length, Immediate(INT32_MAX));
- }
- // Do a zero-length check.
+ // Do a zero-length check. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
// TODO: Support jecxz.
NearLabel not_found_label;
__ testl(string_length, string_length);
__ j(kEqual, ¬_found_label);
+ if (mirror::kUseStringCompression) {
+ string_length_flagged = locations->GetTemp(2).AsRegister<Register>();
+ __ movl(string_length_flagged, string_length);
+ // Extract the length and shift out the least significant bit used as compression flag.
+ __ shrl(string_length, Immediate(1));
+ }
+
if (start_at_zero) {
// Number of chars to scan is the same as the string length.
__ movl(counter, string_length);
@@ -1570,8 +1574,8 @@
if (mirror::kUseStringCompression) {
NearLabel modify_counter, offset_uncompressed_label;
- __ cmpl(string_length_flagged, Immediate(0));
- __ j(kGreaterEqual, &offset_uncompressed_label);
+ __ testl(string_length_flagged, Immediate(1));
+ __ j(kNotZero, &offset_uncompressed_label);
// Move to the start of the string: string_obj + value_offset + start_index.
__ leal(string_obj, Address(string_obj, counter, ScaleFactor::TIMES_1, value_offset));
__ jmp(&modify_counter);
@@ -1593,8 +1597,8 @@
if (mirror::kUseStringCompression) {
NearLabel uncompressed_string_comparison;
NearLabel comparison_done;
- __ cmpl(string_length_flagged, Immediate(0));
- __ j(kGreater, &uncompressed_string_comparison);
+ __ testl(string_length_flagged, Immediate(1));
+ __ j(kNotZero, &uncompressed_string_comparison);
// Check if EAX (search_value) is ASCII.
__ cmpl(search_value, Immediate(127));
@@ -1787,8 +1791,10 @@
__ cfi().AdjustCFAOffset(stack_adjust);
NearLabel copy_loop, copy_uncompressed;
- __ cmpl(Address(obj, count_offset), Immediate(0));
- __ j(kGreaterEqual, ©_uncompressed);
+ __ testl(Address(obj, count_offset), Immediate(1));
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ j(kNotZero, ©_uncompressed);
// Compute the address of the source string by adding the number of chars from
// the source beginning to the value offset of a string.
__ leal(ESI, CodeGeneratorX86::ArrayAddress(obj, srcBegin, TIMES_1, value_offset));
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index de2606c..7ecf4ba 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -1574,20 +1574,23 @@
// compression style is decided on alloc.
__ cmpl(rcx, Address(arg, count_offset));
__ j(kNotEqual, &return_false);
+ // Return true if both strings are empty. Even with string compression `count == 0` means empty.
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ jrcxz(&return_true);
if (mirror::kUseStringCompression) {
NearLabel string_uncompressed;
- // Both string are compressed.
- __ cmpl(rcx, Immediate(0));
- __ j(kGreaterEqual, &string_uncompressed);
+ // Extract length and differentiate between both compressed or both uncompressed.
+ // Different compression style is cut above.
+ __ shrl(rcx, Immediate(1));
+ __ j(kCarrySet, &string_uncompressed);
// Divide string length by 2, rounding up, and continue as if uncompressed.
// Merge clearing the compression flag with +1 for rounding.
- __ addl(rcx, Immediate(static_cast<int32_t>(0x80000001)));
+ __ addl(rcx, Immediate(1));
__ shrl(rcx, Immediate(1));
__ Bind(&string_uncompressed);
}
- // Return true if both strings are empty.
- __ jrcxz(&return_true);
// Load starting addresses of string values into RSI/RDI as required for repe_cmpsq instruction.
__ leal(rsi, Address(str, value_offset));
__ leal(rdi, Address(arg, value_offset));
@@ -1694,21 +1697,22 @@
// Location of count within the String object.
int32_t count_offset = mirror::String::CountOffset().Int32Value();
- // Load string length, i.e., the count field of the string.
+ // Load the count field of the string containing the length and compression flag.
__ movl(string_length, Address(string_obj, count_offset));
- if (mirror::kUseStringCompression) {
- // Use TMP to keep string_length_flagged.
- __ movl(CpuRegister(TMP), string_length);
- // Mask out first bit used as compression flag.
- __ andl(string_length, Immediate(INT32_MAX));
- }
- // Do a length check.
+ // Do a zero-length check. Even with string compression `count == 0` means empty.
// TODO: Support jecxz.
NearLabel not_found_label;
__ testl(string_length, string_length);
__ j(kEqual, ¬_found_label);
+ if (mirror::kUseStringCompression) {
+ // Use TMP to keep string_length_flagged.
+ __ movl(CpuRegister(TMP), string_length);
+ // Mask out first bit used as compression flag.
+ __ shrl(string_length, Immediate(1));
+ }
+
if (start_at_zero) {
// Number of chars to scan is the same as the string length.
__ movl(counter, string_length);
@@ -1728,8 +1732,8 @@
if (mirror::kUseStringCompression) {
NearLabel modify_counter, offset_uncompressed_label;
- __ cmpl(CpuRegister(TMP), Immediate(0));
- __ j(kGreaterEqual, &offset_uncompressed_label);
+ __ testl(CpuRegister(TMP), Immediate(1));
+ __ j(kNotZero, &offset_uncompressed_label);
__ leaq(string_obj, Address(string_obj, counter, ScaleFactor::TIMES_1, value_offset));
__ jmp(&modify_counter);
// Move to the start of the string: string_obj + value_offset + 2 * start_index.
@@ -1747,8 +1751,8 @@
if (mirror::kUseStringCompression) {
NearLabel uncompressed_string_comparison;
NearLabel comparison_done;
- __ cmpl(CpuRegister(TMP), Immediate(0));
- __ j(kGreater, &uncompressed_string_comparison);
+ __ testl(CpuRegister(TMP), Immediate(1));
+ __ j(kNotZero, &uncompressed_string_comparison);
// Check if RAX (search_value) is ASCII.
__ cmpl(search_value, Immediate(127));
__ j(kGreater, ¬_found_label);
@@ -1931,8 +1935,10 @@
// Location of count in string.
const uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
- __ cmpl(Address(obj, count_offset), Immediate(0));
- __ j(kGreaterEqual, ©_uncompressed);
+ __ testl(Address(obj, count_offset), Immediate(1));
+ static_assert(static_cast<uint32_t>(mirror::StringCompressionFlag::kCompressed) == 0u,
+ "Expecting 0=compressed, 1=uncompressed");
+ __ j(kNotZero, ©_uncompressed);
// Compute the address of the source string by adding the number of chars from
// the source beginning to the value offset of a string.
__ leaq(CpuRegister(RSI),