From 9112829d76cbb8e0c8ef51bbc2d7d1be48cd7b74 Mon Sep 17 00:00:00 2001
From: rdivacky <rdivacky@FreeBSD.org>
Date: Tue, 13 Jul 2010 17:19:57 +0000
Subject: Update LLVM to r108243.
---
lib/VMCore/Instruction.cpp | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
(limited to 'lib/VMCore/Instruction.cpp')
diff --git a/lib/VMCore/Instruction.cpp b/lib/VMCore/Instruction.cpp
index a37fe07..9792ada 100644
--- a/lib/VMCore/Instruction.cpp
+++ b/lib/VMCore/Instruction.cpp
@@ -286,9 +286,10 @@ bool Instruction::isUsedOutsideOfBlock(const BasicBlock *BB) const {
for (const_use_iterator UI = use_begin(), E = use_end(); UI != E; ++UI) {
// PHI nodes uses values in the corresponding predecessor block. For other
// instructions, just check to see whether the parent of the use matches up.
- const PHINode *PN = dyn_cast<PHINode>(*UI);
+ const User *U = *UI;
+ const PHINode *PN = dyn_cast<PHINode>(U);
if (PN == 0) {
- if (cast<Instruction>(*UI)->getParent() != BB)
+ if (cast<Instruction>(U)->getParent() != BB)
return true;
continue;
}
@@ -401,12 +402,20 @@ bool Instruction::isSafeToSpeculativelyExecute() const {
return false;
// Note that it is not safe to speculate into a malloc'd region because
// malloc may return null.
- if (isa<AllocaInst>(getOperand(0)))
+ // It's also not safe to follow a bitcast, for example:
+ // bitcast i8* (alloca i8) to i32*
+ // would result in a 4-byte load from a 1-byte alloca.
+ Value *Op0 = getOperand(0);
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0)) {
+ // TODO: it's safe to do this for any GEP with constant indices that
+ // compute inside the allocated type, but not for any inbounds gep.
+ if (GEP->hasAllZeroIndices())
+ Op0 = GEP->getPointerOperand();
+ }
+ if (isa<AllocaInst>(Op0))
return true;
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(getOperand(0)))
return !GV->hasExternalWeakLinkage();
- // FIXME: Handle cases involving GEPs. We have to be careful because
- // a load of a out-of-bounds GEP has undefined behavior.
return false;
}
case Call:
@@ -421,6 +430,7 @@ bool Instruction::isSafeToSpeculativelyExecute() const {
case Store:
case Ret:
case Br:
+ case IndirectBr:
case Switch:
case Unwind:
case Unreachable:
--
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