Change suspend entrypoint to save all registers.
We avoid the need to save/restore registers in slow paths
and get significant code size savings. On Nexus 9, AOSP:
- 32-bit boot.oat: -1.4MiB (-1.9%)
- 64-bit boot.oat: -2.0MiB (-2.3%)
- other 32-bit oat files in dalvik-cache: -200KiB (-1.7%)
- other 64-bit oat files in dalvik-cache: -2.3MiB (-2.1%)
Test: Run ART test suite on host and Nexus 9 with gc stress.
Bug: 30212852
Change-Id: I7015afc1e7d30341618c9200a3dc9ae277afd134
diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 3269dc6..94ecb1c 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -765,16 +765,24 @@
LocationSummary* locations = instruction->GetLocations();
uint32_t register_mask = locations->GetRegisterMask();
- if (locations->OnlyCallsOnSlowPath()) {
- // In case of slow path, we currently set the location of caller-save registers
- // to register (instead of their stack location when pushed before the slow-path
- // call). Therefore register_mask contains both callee-save and caller-save
- // registers that hold objects. We must remove the caller-save from the mask, since
- // they will be overwritten by the callee.
- register_mask &= core_callee_save_mask_;
+ if (instruction->IsSuspendCheck()) {
+ // Suspend check has special ABI that saves the caller-save registers in callee,
+ // so we want to emit stack maps containing the registers.
+ // TODO: Register allocator still reserves space for the caller-save registers.
+ // We should add slow-path-specific caller-save information into LocationSummary
+ // and refactor the code here as well as in the register allocator to use it.
+ } else {
+ if (locations->OnlyCallsOnSlowPath()) {
+ // In case of slow path, we currently set the location of caller-save registers
+ // to register (instead of their stack location when pushed before the slow-path
+ // call). Therefore register_mask contains both callee-save and caller-save
+ // registers that hold objects. We must remove the caller-save from the mask, since
+ // they will be overwritten by the callee.
+ register_mask &= core_callee_save_mask_;
+ }
+ // The register mask must be a subset of callee-save registers.
+ DCHECK_EQ(register_mask & core_callee_save_mask_, register_mask);
}
- // The register mask must be a subset of callee-save registers.
- DCHECK_EQ(register_mask & core_callee_save_mask_, register_mask);
stack_map_stream_.BeginStackMapEntry(outer_dex_pc,
native_pc,
register_mask,