From 8477c7824ca5deadf4314381a5fe5d0c3bfbab99 Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Fri, 30 Aug 2013 18:29:25 +0000
Subject: Pull in r189672 from upstream llvm trunk:
InstCombine: Check for zero shift amounts before subtracting one
causing integer overflow.
PR17026. Also avoid undefined shifts and shift amounts larger than 64
bits (those are always undef because we can't represent integer types
that large).
This should fix assertion failures when building the emulators/xmame
port.
Reported by: bapt
---
.../InstCombine/InstCombineSimplifyDemanded.cpp | 25 +++++++++++++---------
1 file changed, 15 insertions(+), 10 deletions(-)
(limited to 'contrib/llvm/lib/Transforms')
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 8add1ea..60d672b 100644
--- a/contrib/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/contrib/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -845,21 +845,26 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
Value *InstCombiner::SimplifyShrShlDemandedBits(Instruction *Shr,
Instruction *Shl, APInt DemandedMask, APInt &KnownZero, APInt &KnownOne) {
- unsigned ShlAmt = cast<ConstantInt>(Shl->getOperand(1))->getZExtValue();
- unsigned ShrAmt = cast<ConstantInt>(Shr->getOperand(1))->getZExtValue();
+ const APInt &ShlOp1 = cast<ConstantInt>(Shl->getOperand(1))->getValue();
+ const APInt &ShrOp1 = cast<ConstantInt>(Shr->getOperand(1))->getValue();
+ if (!ShlOp1 || !ShrOp1)
+ return 0; // Noop.
+
+ Value *VarX = Shr->getOperand(0);
+ Type *Ty = VarX->getType();
+ unsigned BitWidth = Ty->getIntegerBitWidth();
+ if (ShlOp1.uge(BitWidth) || ShrOp1.uge(BitWidth))
+ return 0; // Undef.
+
+ unsigned ShlAmt = ShlOp1.getZExtValue();
+ unsigned ShrAmt = ShrOp1.getZExtValue();
KnownOne.clearAllBits();
KnownZero = APInt::getBitsSet(KnownZero.getBitWidth(), 0, ShlAmt-1);
KnownZero &= DemandedMask;
- if (ShlAmt == 0 || ShrAmt == 0)
- return 0;
-
- Value *VarX = Shr->getOperand(0);
- Type *Ty = VarX->getType();
-
- APInt BitMask1(APInt::getAllOnesValue(Ty->getIntegerBitWidth()));
- APInt BitMask2(APInt::getAllOnesValue(Ty->getIntegerBitWidth()));
+ APInt BitMask1(APInt::getAllOnesValue(BitWidth));
+ APInt BitMask2(APInt::getAllOnesValue(BitWidth));
bool isLshr = (Shr->getOpcode() == Instruction::LShr);
BitMask1 = isLshr ? (BitMask1.lshr(ShrAmt) << ShlAmt) :
--
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