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Fix a variant of PR6112 found by thinking about it: when doing

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RAUW of a global variable with a local variable in function F,
if function local metadata M in function G was using the global
then M would become function-local to both F and G, which is not
allowed.  See the testcase for an example.  Fixed by detecting
this situation and zapping the metadata operand when it occurs.

llvm-svn: 103007
This commit is contained in:
Duncan Sands 2010-05-04 12:43:36 +00:00
parent 53be8efd62
commit a3857d3d9a
2 changed files with 33 additions and 11 deletions
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28
lib/VMCore/Metadata.cpp
View File

@ -115,14 +115,17 @@ MDNode::~MDNode() {
}
static const Function *getFunctionForValue(Value *V) {
assert(!isa<MDNode>(V) && "does not iterate over metadata operands");
if (!V) return NULL;
if (Instruction *I = dyn_cast<Instruction>(V))
return I->getParent()->getParent();
if (BasicBlock *BB = dyn_cast<BasicBlock>(V))
return BB->getParent();
if (Instruction *I = dyn_cast<Instruction>(V)) {
BasicBlock *BB = I->getParent();
return BB ? BB->getParent() : 0;
}
if (Argument *A = dyn_cast<Argument>(V))
return A->getParent();
if (BasicBlock *BB = dyn_cast<BasicBlock>(V))
return BB->getParent();
if (MDNode *MD = dyn_cast<MDNode>(V))
return MD->getFunction();
return NULL;
}
@ -272,8 +275,19 @@ void MDNode::replaceOperand(MDNodeOperand *Op, Value *To) {
// with an instruction or some other function-local object. If this is a
// non-function-local MDNode, it can't point to a function-local object.
// Handle this case by implicitly dropping the MDNode reference to null.
if (!isFunctionLocal() && To && isFunctionLocalValue(To))
To = 0;
// Likewise if the MDNode is function-local but for a different function.
if (To && isFunctionLocalValue(To)) {
if (!isFunctionLocal())
To = 0;
else {
const Function *F = getFunction();
const Function *FV = getFunctionForValue(To);
// Metadata can be function-local without having an associated function.
// So only consider functions to have changed if non-null.
if (F && FV && F != FV)
To = 0;
}
}
if (From == To)
return;

16
test/Transforms/GlobalOpt/metadata.ll
View File

@ -1,7 +1,8 @@
; RUN: opt -S -globalopt < %s | FileCheck %s
; PR6112 - When globalopt does RAUW(@G, %G), the metadata reference should drop
; to null.
; to null. Function local metadata that references @G from a different function
; to that containing %G should likewise drop to null.
@G = internal global i8** null
define i32 @main(i32 %argc, i8** %argv) {
@ -11,9 +12,16 @@ define i32 @main(i32 %argc, i8** %argv) {
ret i32 0
}
define void @foo(i32 %x) {
call void @llvm.dbg.value(metadata !{i8*** @G, i32 %x}, i64 0, metadata !1)
; CHECK: call void @llvm.dbg.value(metadata !{null, i32 %x}, i64 0, metadata !1)
ret void
}
declare void @llvm.dbg.value(metadata, i64, metadata) nounwind readnone
!named = !{!0}
; CHECK: !0 = metadata !{null}
!0 = metadata !{i8*** @G}
; CHECK: !0 = metadata !{null}
!1 = metadata !{i8* null}