Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(134)

Unified Diff: src/arm64/lithium-codegen-arm64.cc

Issue 227553003: Fixed flooring division by -1 on ARM. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: rebased Created 6 years, 8 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « src/arm/lithium-codegen-arm.cc ('k') | src/ia32/lithium-codegen-ia32.cc » ('j') | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index e52cc868c32639695e0ba285390dc89e24852b35..d885edd090a1d7f2db7d84f82873db5dd05ded6e 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -3851,22 +3851,28 @@ void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
}
// If the divisor is negative, we have to negate and handle edge cases.
- Label not_kmin_int, done;
__ Negs(result, dividend);
if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
DeoptimizeIf(eq, instr->environment());
}
- if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
- // Note that we could emit branch-free code, but that would need one more
- // register.
- if (divisor == -1) {
- DeoptimizeIf(vs, instr->environment());
- } else {
- __ B(vc, &not_kmin_int);
- __ Mov(result, kMinInt / divisor);
- __ B(&done);
- }
+
+ // If the negation could not overflow, simply shifting is OK.
+ if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+ __ Mov(result, Operand(dividend, ASR, shift));
+ return;
}
+
+ // Dividing by -1 is basically negation, unless we overflow.
+ if (divisor == -1) {
+ DeoptimizeIf(vs, instr->environment());
+ return;
+ }
+
+ // Using a conditional data processing instruction would need 1 more register.
+ Label not_kmin_int, done;
+ __ B(vc, &not_kmin_int);
+ __ Mov(result, kMinInt / divisor);
+ __ B(&done);
__ bind(&not_kmin_int);
__ Mov(result, Operand(dividend, ASR, shift));
__ bind(&done);
« no previous file with comments | « src/arm/lithium-codegen-arm.cc ('k') | src/ia32/lithium-codegen-ia32.cc » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698