Reviewers: Benedikt Meurer,
Message:
PTAL
Description:
[turbofan] Second round of optimisation for unordered comparisons on
arm/arm64.
Avoid explicitly branching to the false label on unordered when the
condition
on the true branch will not catch the unordered case and let the code fall
through.
[email protected]
Please review this at https://codereview.chromium.org/794203003/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+18, -12 lines):
M src/compiler/arm/code-generator-arm.cc
M src/compiler/arm64/code-generator-arm64.cc
Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc
b/src/compiler/arm/code-generator-arm.cc
index
dcf03a4a29854fa2afe6323805703270ad6767e9..cfa4de9b3c0a02a4a17be5a1ced19a48c2cdbe08
100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -687,8 +687,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
Label* flabel = branch->false_label;
switch (branch->condition) {
case kUnorderedEqual:
- __ b(vs, flabel);
- // Fall through.
+ // The "eq" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kEqual:
__ b(eq, tlabel);
break;
@@ -711,8 +712,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
__ b(gt, tlabel);
break;
case kUnorderedLessThan:
- __ b(vs, flabel);
- // Fall through.
+ // The "lo" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kUnsignedLessThan:
__ b(lo, tlabel);
break;
@@ -723,8 +725,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
__ b(hs, tlabel);
break;
case kUnorderedLessThanOrEqual:
- __ b(vs, flabel);
- // Fall through.
+ // The "ls" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kUnsignedLessThanOrEqual:
__ b(ls, tlabel);
break;
Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc
b/src/compiler/arm64/code-generator-arm64.cc
index
8cd03784e54e7cc11bea019186d7b8f1cb53ed74..cc46fd677e13bf7d76fd87f2f96a9178b20df04d
100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -781,8 +781,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
} else {
switch (condition) {
case kUnorderedEqual:
- __ B(vs, flabel);
- // Fall through.
+ // The "eq" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kEqual:
__ B(eq, tlabel);
break;
@@ -805,8 +806,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
__ B(gt, tlabel);
break;
case kUnorderedLessThan:
- __ B(vs, flabel);
- // Fall through.
+ // The "lo" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kUnsignedLessThan:
__ B(lo, tlabel);
break;
@@ -817,8 +819,9 @@ void CodeGenerator::AssembleArchBranch(Instruction*
instr, BranchInfo* branch) {
__ B(hs, tlabel);
break;
case kUnorderedLessThanOrEqual:
- __ B(vs, flabel);
- // Fall through.
+ // The "ls" condition will not catch the unordered case.
+ // The jump/fall through to false label will be used if the
comparison
+ // was unordered.
case kUnsignedLessThanOrEqual:
__ B(ls, tlabel);
break;
--
--
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