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Linker: Don't use MDNode::replaceOperandWith()

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`MDNode::replaceOperandWith()` changes all instances of metadata.  Stop
using it when linking module flags, since (due to uniquing) the flag
values could be used by other metadata.

Instead, use new API `NamedMDNode::setOperand()` to update the reference
directly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225397 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith 2015-01-07 21:32:27 +00:00
parent ec1494b99f
commit c742e3a68d
5 changed files with 61 additions and 11 deletions
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1
include/llvm/IR/Metadata.h
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@ -847,6 +847,7 @@ public:
MDNode *getOperand(unsigned i) const;
unsigned getNumOperands() const;
void addOperand(MDNode *M);
void setOperand(unsigned I, MDNode *New);
StringRef getName() const;
void print(raw_ostream &ROS) const;
void dump() const;

5
lib/IR/Metadata.cpp
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@ -836,6 +836,11 @@ MDNode *NamedMDNode::getOperand(unsigned i) const {
void NamedMDNode::addOperand(MDNode *M) { getNMDOps(Operands).emplace_back(M); }
void NamedMDNode::setOperand(unsigned I, MDNode *New) {
assert(I < getNumOperands() && "Invalid operand number");
getNMDOps(Operands)[I].reset(New);
}
void NamedMDNode::eraseFromParent() {
getParent()->eraseNamedMetadata(this);
}

32
lib/Linker/LinkModules.cpp
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@ -1312,7 +1312,7 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
}
// First build a map of the existing module flags and requirements.
DenseMap<MDString*, MDNode*> Flags;
DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
SmallSetVector<MDNode*, 16> Requirements;
for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
MDNode *Op = DstModFlags->getOperand(I);
@ -1322,7 +1322,7 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
if (Behavior->getZExtValue() == Module::Require) {
Requirements.insert(cast<MDNode>(Op->getOperand(2)));
} else {
Flags[ID] = Op;
Flags[ID] = std::make_pair(Op, I);
}
}
@ -1334,7 +1334,9 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
ConstantInt *SrcBehavior =
mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
MDString *ID = cast<MDString>(SrcOp->getOperand(1));
MDNode *DstOp = Flags.lookup(ID);
MDNode *DstOp;
unsigned DstIndex;
std::tie(DstOp, DstIndex) = Flags.lookup(ID);
unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
// If this is a requirement, add it and continue.
@ -1349,7 +1351,7 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
// If there is no existing flag with this ID, just add it.
if (!DstOp) {
Flags[ID] = SrcOp;
Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
DstModFlags->addOperand(SrcOp);
continue;
}
@ -1370,8 +1372,8 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
continue;
} else if (SrcBehaviorValue == Module::Override) {
// Update the destination flag to that of the source.
DstOp->replaceOperandWith(0, ConstantAsMetadata::get(SrcBehavior));
DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
DstModFlags->setOperand(DstIndex, SrcOp);
Flags[ID].first = SrcOp;
continue;
}
@ -1382,6 +1384,13 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
continue;
}
auto replaceDstValue = [&](MDNode *New) {
Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
DstModFlags->setOperand(DstIndex, Flag);
Flags[ID].first = Flag;
};
// Perform the merge for standard behavior types.
switch (SrcBehaviorValue) {
case Module::Require:
@ -1411,7 +1420,8 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
MDs.push_back(DstValue->getOperand(i));
for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
MDs.push_back(SrcValue->getOperand(i));
DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(), MDs));
replaceDstValue(MDNode::get(DstM->getContext(), MDs));
break;
}
case Module::AppendUnique: {
@ -1422,9 +1432,9 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
Elts.insert(DstValue->getOperand(i));
for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
Elts.insert(SrcValue->getOperand(i));
DstOp->replaceOperandWith(
2, MDNode::get(DstM->getContext(),
makeArrayRef(Elts.begin(), Elts.end())));
replaceDstValue(MDNode::get(DstM->getContext(),
makeArrayRef(Elts.begin(), Elts.end())));
break;
}
}
@ -1436,7 +1446,7 @@ bool ModuleLinker::linkModuleFlagsMetadata() {
MDString *Flag = cast<MDString>(Requirement->getOperand(0));
Metadata *ReqValue = Requirement->getOperand(1);
MDNode *Op = Flags[Flag];
MDNode *Op = Flags[Flag].first;
if (!Op || Op->getOperand(2) != ReqValue) {
HasErr |= emitError("linking module flags '" + Flag->getString() +
"': does not have the required value");

8
test/Linker/Inputs/module-flags-dont-change-others.ll Normal file
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@ -0,0 +1,8 @@
!llvm.module.flags = !{!3, !4, !5}
!0 = !{}
!1 = !{!0}
!2 = !{!0, !1}
!3 = !{i32 4, !"foo", i32 37} ; Override the "foo" value.
!4 = !{i32 5, !"bar", !1}
!5 = !{i32 6, !"baz", !2}

26
test/Linker/module-flags-dont-change-others.ll Normal file
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@ -0,0 +1,26 @@
; RUN: llvm-link %s %S/Inputs/module-flags-dont-change-others.ll -S -o - | FileCheck %s
; Test that module-flag linking doesn't change other metadata. In particular,
; !named should still point at the unmodified tuples (!3, !4, and !5) that
; happen to also serve as module flags.
; CHECK: !named = !{!0, !1, !2, !3, !4, !5}
; CHECK: !llvm.module.flags = !{!6, !7, !8}
!named = !{!0, !1, !2, !3, !4, !5}
!llvm.module.flags = !{!3, !4, !5}
; CHECK: !0 = !{}
; CHECK: !1 = !{!0}
; CHECK: !2 = !{!0, !1}
; CHECK: !3 = !{i32 1, !"foo", i32 927}
; CHECK: !4 = !{i32 5, !"bar", !0}
; CHECK: !5 = !{i32 6, !"baz", !1}
; CHECK: !6 = !{i32 4, !"foo", i32 37}
; CHECK: !7 = !{i32 5, !"bar", !1}
; CHECK: !8 = !{i32 6, !"baz", !2}
!0 = !{}
!1 = !{!0}
!2 = !{!0, !1}
!3 = !{i32 1, !"foo", i32 927}
!4 = !{i32 5, !"bar", !0}
!5 = !{i32 6, !"baz", !1}