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Differential D7286

Reassociate: cannot negate a INT_MIN value
ClosedPublic

Authored by mehdi_amini on Jan 29 2015, 5:10 PM.

Details

Reviewers
mcrosier
Commits
rG9730116bd679: Reassociate: cannot negate a INT_MIN value
Summary

When trying to canonicalize negative constants out of
multiplication expressions, we need to check that the
constant is not INT_MIN which cannot be negated.

Diff Detail

Event Timeline

mehdi_amini updated this revision to Diff 19015.Jan 29 2015, 5:10 PM
mehdi_amini retitled this revision from to Reassociate: cannot negate a INT_MIN value.
mehdi_amini updated this object.
mehdi_amini edited the test plan for this revision. (Show Details)
mehdi_amini added a reviewer: mcrosier.
mehdi_amini added a subscriber: Unknown Object (MLST).
mcrosier accepted this revision.Jan 30 2015, 9:37 AM
mcrosier edited edge metadata.
This revision is now accepted and ready to land.Jan 30 2015, 9:37 AM
mehdi_amini closed this revision.Feb 19 2015, 9:57 PM

Revision Contents

PathSize
lib/
Transforms/
Scalar/
2 lines
test/
Transforms/
Reassociate/
13 lines

Diff 19015

lib/Transforms/Scalar/Reassociate.cpp

Show First 20 Lines • Show All 1,985 Lines • ▼ Show 20 LinesInstruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) {
Constant *C1 = dyn_cast<Constant>(I->getOperand(1)); Constant *C1 = dyn_cast<Constant>(I->getOperand(1));
if (!C0 && !C1) if (!C0 && !C1)
return nullptr; return nullptr;
// Must be a negative ConstantInt or ConstantFP. // Must be a negative ConstantInt or ConstantFP.
Constant *C = C0 ? C0 : C1; Constant *C = C0 ? C0 : C1;
unsigned ConstIdx = C0 ? 0 : 1; unsigned ConstIdx = C0 ? 0 : 1;
if (auto *CI = dyn_cast<ConstantInt>(C)) { if (auto *CI = dyn_cast<ConstantInt>(C)) {
if (!CI->isNegative()) if (!CI->isNegative() || CI->isMinValue(true))
return nullptr; return nullptr;
} else if (auto *CF = dyn_cast<ConstantFP>(C)) { } else if (auto *CF = dyn_cast<ConstantFP>(C)) {
if (!CF->isNegative()) if (!CF->isNegative())
return nullptr; return nullptr;
} else } else
return nullptr; return nullptr;
// User must be a binary operator with one or more uses. // User must be a binary operator with one or more uses.
▲ Show 20 Lines • Show All 289 Lines • Show Last 20 Lines

test/Transforms/Reassociate/min_int.ll

  • This file was added.
; RUN: opt < %s -reassociate -dce -S | FileCheck %s
; MIN_INT cannot be negated during reassociation
define i32 @minint(i32 %i) {
; CHECK: %mul = mul i32 %i, -2147483648
; CHECK-NEXT: %add = add i32 %mul, 1
; CHECK-NEXT: ret i32 %add
%mul = mul i32 %i, -2147483648
%add = add i32 %mul, 1
ret i32 %add
}