Create helper class for DWARF expressions.
This ensures we generate valid DWARF opcodes and
it slightly simplifies the debug info writer.
Change-Id: I2ef8a9222c9a129c58f500741acd209b67e2ecff
diff --git a/compiler/dwarf/debug_frame_opcode_writer.h b/compiler/dwarf/debug_frame_opcode_writer.h
index 5a99641..f74f37c 100644
--- a/compiler/dwarf/debug_frame_opcode_writer.h
+++ b/compiler/dwarf/debug_frame_opcode_writer.h
@@ -248,7 +248,7 @@
}
}
- void ALWAYS_INLINE DefCFAExpression(void * expr, int expr_size) {
+ void ALWAYS_INLINE DefCFAExpression(uint8_t* expr, int expr_size) {
if (UNLIKELY(enabled_)) {
ImplicitlyAdvancePC();
uses_dwarf3_features_ = true;
@@ -258,7 +258,7 @@
}
}
- void ALWAYS_INLINE Expression(Reg reg, void * expr, int expr_size) {
+ void ALWAYS_INLINE Expression(Reg reg, uint8_t* expr, int expr_size) {
if (UNLIKELY(enabled_)) {
ImplicitlyAdvancePC();
uses_dwarf3_features_ = true;
@@ -269,7 +269,7 @@
}
}
- void ALWAYS_INLINE ValExpression(Reg reg, void * expr, int expr_size) {
+ void ALWAYS_INLINE ValExpression(Reg reg, uint8_t* expr, int expr_size) {
if (UNLIKELY(enabled_)) {
ImplicitlyAdvancePC();
uses_dwarf3_features_ = true;
diff --git a/compiler/dwarf/debug_info_entry_writer.h b/compiler/dwarf/debug_info_entry_writer.h
index a551e4b..e5bbed3 100644
--- a/compiler/dwarf/debug_info_entry_writer.h
+++ b/compiler/dwarf/debug_info_entry_writer.h
@@ -22,6 +22,7 @@
#include "base/casts.h"
#include "dwarf/dwarf_constants.h"
+#include "dwarf/expression.h"
#include "dwarf/writer.h"
#include "leb128.h"
@@ -106,16 +107,16 @@
}
}
- void WriteBlock(Attribute attrib, const void* ptr, size_t num_bytes) {
+ void WriteBlock(Attribute attrib, const uint8_t* ptr, size_t num_bytes) {
AddAbbrevAttribute(attrib, DW_FORM_block);
this->PushUleb128(num_bytes);
this->PushData(ptr, num_bytes);
}
- void WriteExprLoc(Attribute attrib, const void* ptr, size_t num_bytes) {
+ void WriteExprLoc(Attribute attrib, const Expression& expr) {
AddAbbrevAttribute(attrib, DW_FORM_exprloc);
- this->PushUleb128(dchecked_integral_cast<uint32_t>(num_bytes));
- this->PushData(ptr, num_bytes);
+ this->PushUleb128(dchecked_integral_cast<uint32_t>(expr.size()));
+ this->PushData(expr.data());
}
void WriteData1(Attribute attrib, uint8_t value) {
diff --git a/compiler/dwarf/expression.h b/compiler/dwarf/expression.h
new file mode 100644
index 0000000..1503d03
--- /dev/null
+++ b/compiler/dwarf/expression.h
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_COMPILER_DWARF_EXPRESSION_H_
+#define ART_COMPILER_DWARF_EXPRESSION_H_
+
+#include <cstddef>
+#include <cstdint>
+
+#include "dwarf/dwarf_constants.h"
+#include "dwarf/writer.h"
+
+namespace art {
+namespace dwarf {
+
+// Writer for DWARF expressions which are used in .debug_info and .debug_loc sections.
+// See the DWARF specification for the precise meaning of the opcodes.
+// If multiple equivalent encodings are possible, it will choose the most compact one.
+// The writer is not exhaustive - it only implements opcodes we have needed so far.
+class Expression : private Writer<> {
+ public:
+ using Writer<>::data;
+ using Writer<>::size;
+
+ // Push signed integer on the stack.
+ void WriteOpConsts(int32_t value) {
+ if (0 <= value && value < 32) {
+ PushUint8(DW_OP_lit0 + value);
+ } else {
+ PushUint8(DW_OP_consts);
+ PushSleb128(value);
+ }
+ }
+
+ // Push unsigned integer on the stack.
+ void WriteOpConstu(uint32_t value) {
+ if (value < 32) {
+ PushUint8(DW_OP_lit0 + value);
+ } else {
+ PushUint8(DW_OP_constu);
+ PushUleb128(value);
+ }
+ }
+
+ // Variable is stored in given register.
+ void WriteOpReg(uint32_t dwarf_reg_num) {
+ if (dwarf_reg_num < 32) {
+ PushUint8(DW_OP_reg0 + dwarf_reg_num);
+ } else {
+ PushUint8(DW_OP_regx);
+ PushUleb128(dwarf_reg_num);
+ }
+ }
+
+ // Variable is stored on stack. Also see DW_AT_frame_base.
+ void WriteOpFbreg(int32_t stack_offset) {
+ PushUint8(DW_OP_fbreg);
+ PushSleb128(stack_offset);
+ }
+
+ // The variable is stored in multiple locations (pieces).
+ void WriteOpPiece(uint32_t num_bytes) {
+ PushUint8(DW_OP_piece);
+ PushUleb128(num_bytes);
+ }
+
+ // Loads 32-bit or 64-bit value depending on architecture.
+ void WriteOpDeref() { PushUint8(DW_OP_deref); }
+
+ // Loads value of given byte size.
+ void WriteOpDerefSize(uint8_t num_bytes) {
+ PushUint8(DW_OP_deref_size);
+ PushUint8(num_bytes);
+ }
+
+ // Pop two values and push their sum.
+ void WriteOpPlus() { PushUint8(DW_OP_plus); }
+
+ // Add constant value to value on top of stack.
+ void WriteOpPlusUconst(uint32_t offset) {
+ PushUint8(DW_OP_plus_uconst);
+ PushUleb128(offset);
+ }
+
+ // Negate top of stack.
+ void WriteOpNeg() { PushUint8(DW_OP_neg); }
+
+ // Pop two values and push their bitwise-AND.
+ void WriteOpAnd() { PushUint8(DW_OP_and); }
+
+ // Push stack base pointer as determined from .debug_frame.
+ void WriteOpCallFrameCfa() { PushUint8(DW_OP_call_frame_cfa); }
+
+ // Push address of the variable we are working with.
+ void WriteOpPushObjectAddress() { PushUint8(DW_OP_push_object_address); }
+
+ // Return the top stack as the value of the variable.
+ // Otherwise, the top of stack is the variable's location.
+ void WriteOpStackValue() { PushUint8(DW_OP_stack_value); }
+
+ explicit Expression(std::vector<uint8_t>* buffer) : Writer<>(buffer) {
+ buffer->clear();
+ }
+};
+} // namespace dwarf
+} // namespace art
+
+#endif // ART_COMPILER_DWARF_EXPRESSION_H_
diff --git a/compiler/dwarf/headers.h b/compiler/dwarf/headers.h
index f76f76f..137c566 100644
--- a/compiler/dwarf/headers.h
+++ b/compiler/dwarf/headers.h
@@ -70,7 +70,7 @@
writer.PushUint8(DW_EH_PE_absptr | DW_EH_PE_udata4); // R: Pointer encoding.
}
}
- writer.PushData(*opcodes.data());
+ writer.PushData(opcodes.data());
writer.Pad(is64bit ? 8 : 4);
writer.UpdateUint32(cie_header_start_, writer.data()->size() - cie_header_start_ - 4);
}
@@ -117,7 +117,7 @@
writer.PushUint32(code_size);
}
writer.PushUleb128(0); // Augmentation data size.
- writer.PushData(opcodes);
+ writer.PushData(opcodes.data(), opcodes.size());
writer.Pad(is64bit ? 8 : 4);
writer.UpdateUint32(fde_header_start, writer.data()->size() - fde_header_start - 4);
}
@@ -139,7 +139,7 @@
writer.PushUint8(entries.Is64bit() ? 8 : 4);
size_t entries_offset = writer.data()->size();
DCHECK_EQ(entries_offset, DebugInfoEntryWriter<Vector>::kCompilationUnitHeaderSize);
- writer.PushData(*entries.data());
+ writer.PushData(entries.data());
writer.UpdateUint32(start, writer.data()->size() - start - 4);
// Copy patch locations and make them relative to .debug_info section.
for (uintptr_t patch_location : entries.GetPatchLocations()) {
@@ -193,7 +193,7 @@
writer.PushUint8(0); // Terminate file list.
writer.UpdateUint32(header_length_pos, writer.data()->size() - header_length_pos - 4);
size_t opcodes_offset = writer.data()->size();
- writer.PushData(*opcodes.data());
+ writer.PushData(opcodes.data());
writer.UpdateUint32(header_start, writer.data()->size() - header_start - 4);
// Copy patch locations and make them relative to .debug_line section.
for (uintptr_t patch_location : opcodes.GetPatchLocations()) {
diff --git a/compiler/dwarf/writer.h b/compiler/dwarf/writer.h
index d2add7f..74acf07 100644
--- a/compiler/dwarf/writer.h
+++ b/compiler/dwarf/writer.h
@@ -114,16 +114,16 @@
data_->insert(data_->end(), value, value + strlen(value) + 1);
}
- void PushData(const void* ptr, size_t num_bytes) {
- const char* p = reinterpret_cast<const char*>(ptr);
- data_->insert(data_->end(), p, p + num_bytes);
+ void PushData(const uint8_t* ptr, size_t num_bytes) {
+ data_->insert(data_->end(), ptr, ptr + num_bytes);
}
- template<typename Vector2>
- void PushData(const Vector2& buffer) {
- static_assert(std::is_same<typename std::add_const<typename Vector::value_type>::type,
- const uint8_t>::value, "Invalid value type");
- data_->insert(data_->end(), buffer.begin(), buffer.end());
+ void PushData(const char* ptr, size_t num_bytes) {
+ data_->insert(data_->end(), ptr, ptr + num_bytes);
+ }
+
+ void PushData(const Vector* buffer) {
+ data_->insert(data_->end(), buffer->begin(), buffer->end());
}
void UpdateUint32(size_t offset, uint32_t value) {
diff --git a/compiler/elf_writer_debug.cc b/compiler/elf_writer_debug.cc
index 3e64762..99d2b84 100644
--- a/compiler/elf_writer_debug.cc
+++ b/compiler/elf_writer_debug.cc
@@ -25,6 +25,7 @@
#include "dex_file-inl.h"
#include "driver/compiler_driver.h"
#include "dwarf/dedup_vector.h"
+#include "dwarf/expression.h"
#include "dwarf/headers.h"
#include "dwarf/method_debug_info.h"
#include "dwarf/register.h"
@@ -498,8 +499,10 @@
WriteName(dex->GetMethodName(dex_method));
info_.WriteAddr(DW_AT_low_pc, text_address + mi->low_pc_);
info_.WriteUdata(DW_AT_high_pc, dchecked_integral_cast<uint32_t>(mi->high_pc_-mi->low_pc_));
- uint8_t frame_base[] = { DW_OP_call_frame_cfa };
- info_.WriteExprLoc(DW_AT_frame_base, &frame_base, sizeof(frame_base));
+ std::vector<uint8_t> expr_buffer;
+ Expression expr(&expr_buffer);
+ expr.WriteOpCallFrameCfa();
+ info_.WriteExprLoc(DW_AT_frame_base, expr);
WriteLazyType(dex->GetReturnTypeDescriptor(dex_proto));
// Write parameters. DecodeDebugLocalInfo returns them as well, but it does not
@@ -588,6 +591,7 @@
info_.WriteStrp(DW_AT_producer, owner_->WriteString("Android dex2oat"));
info_.WriteData1(DW_AT_language, DW_LANG_Java);
+ std::vector<uint8_t> count_expr_buffer;
for (mirror::Class* type : types) {
if (type->IsPrimitive()) {
// For primitive types the definition and the declaration is the same.
@@ -605,15 +609,11 @@
WriteLazyType(element_type->GetDescriptor(&descriptor_string));
info_.WriteUdata(DW_AT_data_member_location, data_offset);
info_.StartTag(DW_TAG_subrange_type);
- DCHECK_LT(length_offset, 32u);
- uint8_t count[] = {
- DW_OP_push_object_address,
- static_cast<uint8_t>(DW_OP_lit0 + length_offset),
- DW_OP_plus,
- DW_OP_deref_size,
- 4 // Array length is always 32-bit wide.
- };
- info_.WriteExprLoc(DW_AT_count, &count, sizeof(count));
+ Expression count_expr(&count_expr_buffer);
+ count_expr.WriteOpPushObjectAddress();
+ count_expr.WriteOpPlusUconst(length_offset);
+ count_expr.WriteOpDerefSize(4); // Array length is always 32-bit wide.
+ info_.WriteExprLoc(DW_AT_count, count_expr);
info_.EndTag(); // DW_TAG_subrange_type.
info_.EndTag(); // DW_TAG_array_type.
} else {
@@ -713,12 +713,12 @@
// Write .debug_loc entries.
const InstructionSet isa = owner_->builder_->GetIsa();
const bool is64bit = Is64BitInstructionSet(isa);
+ std::vector<uint8_t> expr_buffer;
for (const VariableLocation& variable_location : variable_locations) {
// Translate dex register location to DWARF expression.
// Note that 64-bit value might be split to two distinct locations.
// (for example, two 32-bit machine registers, or even stack and register)
- uint8_t buffer[64];
- uint8_t* pos = buffer;
+ Expression expr(&expr_buffer);
DexRegisterLocation reg_lo = variable_location.reg_lo;
DexRegisterLocation reg_hi = variable_location.reg_hi;
for (int piece = 0; piece < (is64bitValue ? 2 : 1); piece++) {
@@ -727,15 +727,14 @@
const int32_t value = reg_loc.GetValue();
if (kind == Kind::kInStack) {
const size_t frame_size = method_info->compiled_method_->GetFrameSizeInBytes();
- *(pos++) = DW_OP_fbreg;
// The stack offset is relative to SP. Make it relative to CFA.
- pos = EncodeSignedLeb128(pos, value - frame_size);
+ expr.WriteOpFbreg(value - frame_size);
if (piece == 0 && reg_hi.GetKind() == Kind::kInStack &&
reg_hi.GetValue() == value + 4) {
break; // the high word is correctly implied by the low word.
}
} else if (kind == Kind::kInRegister) {
- pos = WriteOpReg(pos, GetDwarfCoreReg(isa, value).num());
+ expr.WriteOpReg(GetDwarfCoreReg(isa, value).num());
if (piece == 0 && reg_hi.GetKind() == Kind::kInRegisterHigh &&
reg_hi.GetValue() == value) {
break; // the high word is correctly implied by the low word.
@@ -745,22 +744,21 @@
piece == 0 && reg_hi.GetKind() == Kind::kInFpuRegister &&
reg_hi.GetValue() == value + 1 && value % 2 == 0) {
// Translate S register pair to D register (e.g. S4+S5 to D2).
- pos = WriteOpReg(pos, Reg::ArmDp(value / 2).num());
+ expr.WriteOpReg(Reg::ArmDp(value / 2).num());
break;
}
if (isa == kMips || isa == kMips64) {
// TODO: Find what the DWARF floating point register numbers are on MIPS.
break;
}
- pos = WriteOpReg(pos, GetDwarfFpReg(isa, value).num());
+ expr.WriteOpReg(GetDwarfFpReg(isa, value).num());
if (piece == 0 && reg_hi.GetKind() == Kind::kInFpuRegisterHigh &&
reg_hi.GetValue() == reg_lo.GetValue()) {
break; // the high word is correctly implied by the low word.
}
} else if (kind == Kind::kConstant) {
- *(pos++) = DW_OP_consts;
- pos = EncodeSignedLeb128(pos, value);
- *(pos++) = DW_OP_stack_value;
+ expr.WriteOpConsts(value);
+ expr.WriteOpStackValue();
} else if (kind == Kind::kNone) {
break;
} else {
@@ -774,14 +772,11 @@
if (is64bitValue) {
// Write the marker which is needed by split 64-bit values.
// This code is skipped by the special cases.
- *(pos++) = DW_OP_piece;
- pos = EncodeUnsignedLeb128(pos, 4);
+ expr.WriteOpPiece(4);
}
}
- // Check that the buffer is large enough; keep half of it empty for safety.
- DCHECK_LE(static_cast<size_t>(pos - buffer), sizeof(buffer) / 2);
- if (pos > buffer) {
+ if (expr.size() > 0) {
if (is64bit) {
debug_loc.PushUint64(variable_location.low_pc - compilation_unit_low_pc);
debug_loc.PushUint64(variable_location.high_pc - compilation_unit_low_pc);
@@ -790,8 +785,8 @@
debug_loc.PushUint32(variable_location.high_pc - compilation_unit_low_pc);
}
// Write the expression.
- debug_loc.PushUint16(pos - buffer);
- debug_loc.PushData(buffer, pos - buffer);
+ debug_loc.PushUint16(expr.size());
+ debug_loc.PushData(expr.data());
} else {
// Do not generate .debug_loc if the location is not known.
}
@@ -856,17 +851,6 @@
}
}
- // Helper which writes DWARF expression referencing a register.
- static uint8_t* WriteOpReg(uint8_t* buffer, uint32_t dwarf_reg_num) {
- if (dwarf_reg_num < 32) {
- *(buffer++) = DW_OP_reg0 + dwarf_reg_num;
- } else {
- *(buffer++) = DW_OP_regx;
- buffer = EncodeUnsignedLeb128(buffer, dwarf_reg_num);
- }
- return buffer;
- }
-
// Convert dex type descriptor to DWARF.
// Returns offset in the compilation unit.
size_t WriteTypeDeclaration(const std::string& desc) {