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authorBob Wilson <bob.wilson@apple.com>2013-11-15 19:09:27 +0000
committerBob Wilson <bob.wilson@apple.com>2013-11-15 19:09:27 +0000
commitcc7052343e5e955d4e2f48885c06360f9003390a (patch)
tree8832fd14ebae789ee88bab5009cc33fbc89e3ec7 /lib/CodeGen/SelectionDAG
parent5cddda6d13ab66c462ccbd61255ad6e6f95e9f6f (diff)
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Avoid illegal integer promotion in fastisel
Stop folding constant adds into GEP when the type size doesn't match. Otherwise, the adds' operands are effectively being promoted, changing the conditions of an overflow. Results are different when: sext(a) + sext(b) != sext(a + b) Problem originally found on x86-64, but also fixed issues with ARM and PPC, which used similar code. <rdar://problem/15292280> Patch by Duncan Exon Smith! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194840 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG')
-rw-r--r--lib/CodeGen/SelectionDAG/FastISel.cpp15
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index fb798c1..a6f7461 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1571,4 +1571,19 @@ bool FastISel::tryToFoldLoad(const LoadInst *LI, const Instruction *FoldInst) {
return tryToFoldLoadIntoMI(User, RI.getOperandNo(), LI);
}
+bool FastISel::canFoldAddIntoGEP(const User *GEP, const Value *Add) {
+ // Must be an add.
+ if (!isa<AddOperator>(Add))
+ return false;
+ // Type size needs to match.
+ if (TD.getTypeSizeInBits(GEP->getType()) !=
+ TD.getTypeSizeInBits(Add->getType()))
+ return false;
+ // Must be in the same basic block.
+ if (isa<Instruction>(Add) &&
+ FuncInfo.MBBMap[cast<Instruction>(Add)->getParent()] != FuncInfo.MBB)
+ return false;
+ // Must have a constant operand.
+ return isa<ConstantInt>(cast<AddOperator>(Add)->getOperand(1));
+}