Revert "Revert "Use implicit null checks inside try blocks.""
Fix implicit checks in try blocks to emit stack maps.
Fix arm64 null expection from signal entrypoint to call
the runtime handler instead or simply jumping there.
On Nexus 9, AOSP ToT, the boot.oat size reduction is
prebuilt multi-part boot image:
- 32-bit boot.oat: -448KiB (-1.3%)
- 64-bit boot.oat: -528KiB (-1.2%)
on-device built single boot image:
- 32-bit boot.oat: -448KiB (-1.4%)
- 64-bit boot.oat: -528KiB (-1.3%)
Note that the oat files no longer contain dex files which
have been moved to vdex, so the percentages are not directly
comparable with the those reported in the original commit.
Test: Run ART test suite including gc-stress on host and Nexus 9.
Bug: 30212852
Bug: 31468464
This reverts commit 0719b5b9b458cb3eb9f0823f0dacdfe1a71214dd.
Change-Id: If8a9da8c11adf2aad203e93b6684ce16ed776285
diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 2087888..6732670 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -1081,13 +1081,6 @@
}
}
-bool CodeGenerator::IsImplicitNullCheckAllowed(HNullCheck* null_check) const {
- return compiler_options_.GetImplicitNullChecks() &&
- // Null checks which might throw into a catch block need to save live
- // registers and therefore cannot be done implicitly.
- !null_check->CanThrowIntoCatchBlock();
-}
-
bool CodeGenerator::CanMoveNullCheckToUser(HNullCheck* null_check) {
HInstruction* first_next_not_move = null_check->GetNextDisregardingMoves();
@@ -1096,6 +1089,10 @@
}
void CodeGenerator::MaybeRecordImplicitNullCheck(HInstruction* instr) {
+ if (!compiler_options_.GetImplicitNullChecks()) {
+ return;
+ }
+
// If we are from a static path don't record the pc as we can't throw NPE.
// NB: having the checks here makes the code much less verbose in the arch
// specific code generators.
@@ -1114,16 +1111,35 @@
// and needs to record the pc.
if (first_prev_not_move != nullptr && first_prev_not_move->IsNullCheck()) {
HNullCheck* null_check = first_prev_not_move->AsNullCheck();
- if (IsImplicitNullCheckAllowed(null_check)) {
- // TODO: The parallel moves modify the environment. Their changes need to be
- // reverted otherwise the stack maps at the throw point will not be correct.
- RecordPcInfo(null_check, null_check->GetDexPc());
- }
+ // TODO: The parallel moves modify the environment. Their changes need to be
+ // reverted otherwise the stack maps at the throw point will not be correct.
+ RecordPcInfo(null_check, null_check->GetDexPc());
}
}
+LocationSummary* CodeGenerator::CreateNullCheckLocations(HNullCheck* null_check) {
+ // Note: Using kNoCall allows the method to be treated as leaf (and eliminate the
+ // HSuspendCheck from entry block). However, it will still get a valid stack frame
+ // because the HNullCheck needs an environment.
+ LocationSummary::CallKind call_kind = LocationSummary::kNoCall;
+ // When throwing from a try block, we may need to retrieve dalvik registers from
+ // physical registers and we also need to set up stack mask for GC. This is
+ // implicitly achieved by passing kCallOnSlowPath to the LocationSummary.
+ bool can_throw_into_catch_block = null_check->CanThrowIntoCatchBlock();
+ if (can_throw_into_catch_block) {
+ call_kind = LocationSummary::kCallOnSlowPath;
+ }
+ LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(null_check, call_kind);
+ if (can_throw_into_catch_block && compiler_options_.GetImplicitNullChecks()) {
+ locations->SetCustomSlowPathCallerSaves(RegisterSet()); // No caller-save registers.
+ }
+ locations->SetInAt(0, Location::RequiresRegister());
+ DCHECK(!null_check->HasUses());
+ return locations;
+}
+
void CodeGenerator::GenerateNullCheck(HNullCheck* instruction) {
- if (IsImplicitNullCheckAllowed(instruction)) {
+ if (compiler_options_.GetImplicitNullChecks()) {
MaybeRecordStat(kImplicitNullCheckGenerated);
GenerateImplicitNullCheck(instruction);
} else {