Reviewers: jochen, ulan,
Message:
PTAL
Description:
ARM64: Use a double register to break cycle involving double values.
[email protected], [email protected]
Please review this at https://codereview.chromium.org/208183002/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+21, -13 lines):
M src/arm64/lithium-gap-resolver-arm64.cc
Index: src/arm64/lithium-gap-resolver-arm64.cc
diff --git a/src/arm64/lithium-gap-resolver-arm64.cc
b/src/arm64/lithium-gap-resolver-arm64.cc
index
de6717a7707b599749ba9eed23b2acd7c635a751..f0a2e6bd0e3da8f028b27b3a7de6852b2d3d9f32
100644
--- a/src/arm64/lithium-gap-resolver-arm64.cc
+++ b/src/arm64/lithium-gap-resolver-arm64.cc
@@ -42,6 +42,12 @@ namespace internal {
// once we have resolved a cycle.
#define kSavedValue root
+// We use the MacroAssembler floating-point scratch register to break a
cycle
+// involving double values as the MacroAssembler will not need it for the
+// operations performed by the gap resolver.
+#define kSavedDoubleValue fp_scratch
+
+
LGapResolver::LGapResolver(LCodeGen* owner)
: cgen_(owner), moves_(32, owner->zone()), root_index_(0),
in_cycle_(false),
saved_destination_(NULL), need_to_restore_root_(false) { }
@@ -169,10 +175,10 @@ void LGapResolver::BreakCycle(int index) {
ASSERT(moves_[index].destination()->Equals(moves_[root_index_].source()));
ASSERT(!in_cycle_);
- // We use a register which is not allocatable by crankshaft to break the
cycle
- // to be sure it doesn't interfere with the moves we are resolving.
+ // We use registers which are not allocatable by crankshaft to break the
cycle
+ // to be sure they don't interfere with the moves we are resolving.
ASSERT(!kSavedValue.IsAllocatable());
- need_to_restore_root_ = true;
+ ASSERT(!kSavedDoubleValue.IsAllocatable());
// We save in a register the source of that move and we remember its
// destination. Then we mark this move as resolved so the cycle is
@@ -182,19 +188,19 @@ void LGapResolver::BreakCycle(int index) {
saved_destination_ = moves_[index].destination();
if (source->IsRegister()) {
+ need_to_restore_root_ = true;
__ Mov(kSavedValue, cgen_->ToRegister(source));
} else if (source->IsStackSlot()) {
+ need_to_restore_root_ = true;
__ Ldr(kSavedValue, cgen_->ToMemOperand(source));
} else if (source->IsDoubleRegister()) {
- // TODO(all): We should use a double register to store the value to
avoid
- // the penalty of the mov across register banks. We are going to
reserve
- // d31 to hold 0.0 value. We could clobber this register while
breaking the
- // cycle and restore it after like we do with the root register.
- // LGapResolver::RestoreValue() will need to be updated as well when
we'll
- // do that.
- __ Fmov(kSavedValue, cgen_->ToDoubleRegister(source));
+ ASSERT(cgen_->masm()->FPTmpList()->IncludesAliasOf(kSavedDoubleValue));
+ cgen_->masm()->FPTmpList()->Remove(kSavedDoubleValue);
+ __ Fmov(kSavedDoubleValue, cgen_->ToDoubleRegister(source));
} else if (source->IsDoubleStackSlot()) {
- __ Ldr(kSavedValue, cgen_->ToMemOperand(source));
+ ASSERT(cgen_->masm()->FPTmpList()->IncludesAliasOf(kSavedDoubleValue));
+ cgen_->masm()->FPTmpList()->Remove(kSavedDoubleValue);
+ __ Ldr(kSavedDoubleValue, cgen_->ToMemOperand(source));
} else {
UNREACHABLE();
}
@@ -215,9 +221,11 @@ void LGapResolver::RestoreValue() {
} else if (saved_destination_->IsStackSlot()) {
__ Str(kSavedValue, cgen_->ToMemOperand(saved_destination_));
} else if (saved_destination_->IsDoubleRegister()) {
- __ Fmov(cgen_->ToDoubleRegister(saved_destination_), kSavedValue);
+ __ Fmov(cgen_->ToDoubleRegister(saved_destination_),
kSavedDoubleValue);
+ cgen_->masm()->FPTmpList()->Combine(kSavedDoubleValue);
} else if (saved_destination_->IsDoubleStackSlot()) {
- __ Str(kSavedValue, cgen_->ToMemOperand(saved_destination_));
+ __ Str(kSavedDoubleValue, cgen_->ToMemOperand(saved_destination_));
+ cgen_->masm()->FPTmpList()->Combine(kSavedDoubleValue);
} else {
UNREACHABLE();
}
--
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