ART: Optimize StringBuilder append pattern.
Recognize appending with StringBuilder and replace the
entire expression with a runtime call that perfoms the
append in a more efficient manner.
For now, require the entire pattern to be in a single block
and be very strict about the StringBuilder environment uses.
Also, do not accept StringBuilder/char[]/Object/float/double
arguments as they throw non-OOME exceptions and/or require a
call from the entrypoint back to a helper function in Java;
these shall be implemented later.
Boot image size for aosp_taimen-userdebug:
- before:
arm/boot*.oat: 19653872
arm64/boot*.oat: 23292784
oat/arm64/services.odex: 22408664
- after:
arm/boot*.oat: 19432184 (-216KiB)
arm64/boot*.oat: 22992488 (-293KiB)
oat/arm64/services.odex: 22376776 (-31KiB)
Note that const-string in compiled boot image methods cannot
throw, but for apps it can and therefore its environment can
prevent the optimization for apps. We could implement either
a simple carve-out for const-string or generic environment
pruning to allow this pattern to be applied more often.
Results for the new StringBuilderAppendBenchmark on taimen:
timeAppendLongStrings: ~700ns -> ~200ns
timeAppendStringAndInt: ~220ns -> ~140ns
timeAppendStrings: ~200ns -> 130ns
Bug: 19575890
Test: 697-checker-string-append
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: aosp_taimen-userdebug boots.
Test: run-gtests.sh
Test: testrunner.py --target --optimizing
Test: vogar --benchmark art/benchmark/stringbuilder-append/src/StringBuilderAppendBenchmark.java
Change-Id: I51789bf299f5219f68ada4c077b6a1d3fe083964
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index ca1723b..7a73569 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -5510,6 +5510,15 @@
HandleFieldGet(instruction, instruction->GetFieldInfo());
}
+void LocationsBuilderX86::VisitStringBuilderAppend(HStringBuilderAppend* instruction) {
+ codegen_->CreateStringBuilderAppendLocations(instruction, Location::RegisterLocation(EAX));
+}
+
+void InstructionCodeGeneratorX86::VisitStringBuilderAppend(HStringBuilderAppend* instruction) {
+ __ movl(EAX, Immediate(instruction->GetFormat()->GetValue()));
+ codegen_->InvokeRuntime(kQuickStringBuilderAppend, instruction, instruction->GetDexPc());
+}
+
void LocationsBuilderX86::VisitUnresolvedInstanceFieldGet(
HUnresolvedInstanceFieldGet* instruction) {
FieldAccessCallingConventionX86 calling_convention;