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fix PR6197 - infinite recursion in ipsccp due to block addresses

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evaluateICmpRelation wasn't handling blockaddress.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94993 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-02-01 19:35:08 +00:00
parent c6654ec498
commit b63127d435
2 changed files with 59 additions and 19 deletions
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66
lib/VMCore/ConstantFold.cpp
View File

@ -1506,15 +1506,16 @@ static FCmpInst::Predicate evaluateFCmpRelation(LLVMContext &Context,
/// GlobalValues, followed by ConstantExpr's (the most complex).
///
static ICmpInst::Predicate evaluateICmpRelation(LLVMContext &Context,
Constant *V1,
Constant *V2,
Constant *V1, Constant *V2,
bool isSigned) {
assert(V1->getType() == V2->getType() &&
"Cannot compare different types of values!");
if (V1 == V2) return ICmpInst::ICMP_EQ;
if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) &&
!isa<BlockAddress>(V1)) {
if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) &&
!isa<BlockAddress>(V2)) {
// We distilled this down to a simple case, use the standard constant
// folder.
ConstantInt *R = 0;
@ -1541,32 +1542,59 @@ static ICmpInst::Predicate evaluateICmpRelation(LLVMContext &Context,
if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
return ICmpInst::getSwappedPredicate(SwappedRelation);
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
} else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) {
if (isa<ConstantExpr>(V2)) { // Swap as necessary.
ICmpInst::Predicate SwappedRelation =
evaluateICmpRelation(Context, V2, V1, isSigned);
if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
return ICmpInst::getSwappedPredicate(SwappedRelation);
else
return ICmpInst::BAD_ICMP_PREDICATE;
return ICmpInst::BAD_ICMP_PREDICATE;
}
// Now we know that the RHS is a GlobalValue or simple constant,
// which (since the types must match) means that it's a ConstantPointerNull.
if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
// Now we know that the RHS is a GlobalValue, BlockAddress or simple
// constant (which, since the types must match, means that it's a
// ConstantPointerNull).
if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) {
// Don't try to decide equality of aliases.
if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
if (!isa<GlobalAlias>(GV) && !isa<GlobalAlias>(GV2))
if (!GV->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage())
return ICmpInst::ICMP_NE;
} else if (isa<BlockAddress>(V2)) {
return ICmpInst::ICMP_NE; // Globals never equal labels.
} else {
assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
// GlobalVals can never be null. Don't try to evaluate aliases.
if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
// GlobalVals can never be null unless they have external weak linkage.
// We don't try to evaluate aliases here.
if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV))
return ICmpInst::ICMP_NE;
}
} else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) {
if (isa<ConstantExpr>(V2)) { // Swap as necessary.
ICmpInst::Predicate SwappedRelation =
evaluateICmpRelation(Context, V2, V1, isSigned);
if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
return ICmpInst::getSwappedPredicate(SwappedRelation);
return ICmpInst::BAD_ICMP_PREDICATE;
}
// Now we know that the RHS is a GlobalValue, BlockAddress or simple
// constant (which, since the types must match, means that it is a
// ConstantPointerNull).
if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) {
// Block address in another function can't equal this one, but block
// addresses in the current function might be the same if blocks are
// empty.
if (BA2->getFunction() != BA->getFunction())
return ICmpInst::ICMP_NE;
} else {
// Block addresses aren't null, don't equal the address of globals.
assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) &&
"Canonicalization guarantee!");
return ICmpInst::ICMP_NE;
}
} else {
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
// constantexpr, a CPR, or a simple constant.
// constantexpr, a global, block address, or a simple constant.
ConstantExpr *CE1 = cast<ConstantExpr>(V1);
Constant *CE1Op0 = CE1->getOperand(0);
@ -1621,9 +1649,9 @@ static ICmpInst::Predicate evaluateICmpRelation(LLVMContext &Context,
return ICmpInst::ICMP_EQ;
}
// Otherwise, we can't really say if the first operand is null or not.
} else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
} else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) {
if (isa<ConstantPointerNull>(CE1Op0)) {
if (CPR2->hasExternalWeakLinkage())
if (GV2->hasExternalWeakLinkage())
// Weak linkage GVals could be zero or not. We're comparing it to
// a null pointer, so its less-or-equal
return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
@ -1631,8 +1659,8 @@ static ICmpInst::Predicate evaluateICmpRelation(LLVMContext &Context,
// If its not weak linkage, the GVal must have a non-zero address
// so the result is less-than
return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
if (CPR1 == CPR2) {
} else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
if (GV == GV2) {
// If this is a getelementptr of the same global, then it must be
// different. Because the types must match, the getelementptr could
// only have at most one index, and because we fold getelementptr's

12
test/Transforms/ConstProp/basictest.ll
View File

@ -19,3 +19,15 @@ BB3:
ret i32 %Ret
}
; PR6197
define i1 @test2(i8* %f) nounwind {
entry:
%V = icmp ne i8* blockaddress(@test2, %bb), null
br label %bb
bb:
ret i1 %V
; CHECK: @test2
; CHECK: ret i1 true
}