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Reassociate: cannot negate a INT_MIN value

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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.

Reviewers: mcrosier

Reviewed By: mcrosier

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7286

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228872 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mehdi Amini 2015-02-11 19:54:44 +00:00
parent 293dfe59a5
commit 23af697ae6
2 changed files with 14 additions and 1 deletions
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2
lib/Transforms/Scalar/Reassociate.cpp
View File

@ -1991,7 +1991,7 @@ Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) {
Constant *C = C0 ? C0 : C1;
unsigned ConstIdx = C0 ? 0 : 1;
if (auto *CI = dyn_cast<ConstantInt>(C)) {
if (!CI->isNegative())
if (!CI->isNegative() || CI->isMinValue(true))
return nullptr;
} else if (auto *CF = dyn_cast<ConstantFP>(C)) {
if (!CF->isNegative())

13
test/Transforms/Reassociate/min_int.ll Normal file
View File

@ -0,0 +1,13 @@
; 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
}