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Handle value uses wrapped in metadata for the use-list order 

When generating the use-list order, also consider value uses that are
operands which are wrapped in metadata; e.g. llvm.dbg.value operands.

This fixes PR36778. The test case is based on the reproducer from that
report.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D53758
This commit is contained in:
David Stenberg 2020-10-20 19:30:39 +02:00
parent cf9e54ef49
commit 0c0fcea557
4 changed files with 115 additions and 6 deletions
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29
llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
View File

@ -78,6 +78,16 @@ struct OrderMap {
} // end anonymous namespace
/// Look for a value that might be wrapped as metadata, e.g. a value in a
/// metadata operand. Returns nullptr for a non-wrapped input value if
/// OnlyWrapped is true, or it returns the input value as-is if false.
static const Value *skipMetadataWrapper(const Value *V, bool OnlyWrapped) {
if (const auto *MAV = dyn_cast<MetadataAsValue>(V))
if (const auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
return VAM->getValue();
return OnlyWrapped ? nullptr : V;
}
static void orderValue(const Value *V, OrderMap &OM) {
if (OM.lookup(V).first)
return;
@ -123,6 +133,25 @@ static OrderMap orderModule(const Module &M) {
if (!isa<GlobalValue>(U.get()))
orderValue(U.get(), OM);
}
// As constants used in metadata operands are emitted as module-level
// constants, we must order them before other operands. Also, we must order
// these before global values, as these will be read before setting the
// global values' initializers. The latter matters for constants which have
// uses towards other constants that are used as initializers.
for (const Function &F : M) {
if (F.isDeclaration())
continue;
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
for (const Value *V : I.operands()) {
if (const Value *Op = skipMetadataWrapper(V, true)) {
if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
isa<InlineAsm>(*Op))
orderValue(Op, OM);
}
}
}
OM.LastGlobalConstantID = OM.size();
// Initializers of GlobalValues are processed in

19
llvm/lib/IR/AsmWriter.cpp
View File

@ -116,6 +116,15 @@ struct OrderMap {
} // end anonymous namespace
/// Look for a value that might be wrapped as metadata, e.g. a value in a
/// metadata operand. Returns the input value as-is if it is not wrapped.
static const Value *skipMetadataWrapper(const Value *V) {
if (const auto *MAV = dyn_cast<MetadataAsValue>(V))
if (const auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
return VAM->getValue();
return V;
}
static void orderValue(const Value *V, OrderMap &OM) {
if (OM.lookup(V).first)
return;
@ -132,8 +141,6 @@ static void orderValue(const Value *V, OrderMap &OM) {
}
static OrderMap orderModule(const Module *M) {
// This needs to match the order used by ValueEnumerator::ValueEnumerator()
// and ValueEnumerator::incorporateFunction().
OrderMap OM;
for (const GlobalVariable &G : M->globals()) {
@ -167,10 +174,12 @@ static OrderMap orderModule(const Module *M) {
for (const BasicBlock &BB : F) {
orderValue(&BB, OM);
for (const Instruction &I : BB) {
for (const Value *Op : I.operands())
for (const Value *Op : I.operands()) {
Op = skipMetadataWrapper(Op);
if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
isa<InlineAsm>(*Op))
orderValue(Op, OM);
}
orderValue(&I, OM);
}
}
@ -284,9 +293,11 @@ static UseListOrderStack predictUseListOrder(const Module *M) {
predictValueUseListOrder(&A, &F, OM, Stack);
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
for (const Value *Op : I.operands())
for (const Value *Op : I.operands()) {
Op = skipMetadataWrapper(Op);
if (isa<Constant>(*Op) || isa<InlineAsm>(*Op)) // Visit GlobalValues.
predictValueUseListOrder(Op, &F, OM, Stack);
}
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
predictValueUseListOrder(&I, &F, OM, Stack);

58
llvm/test/Assembler/metadata-use-uselistorder.ll Normal file
View File

@ -0,0 +1,58 @@
; RUN: verify-uselistorder %s
; Reproducer for PR36778.
; Verify that uses in metadata operands are considered when generating the
; use-list order. In this case the use-list order for @global_arr was not
; correctly preserved due to the uses in the dbg.value contant expressions not
; being considered, since they are wrapped in metadata.
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@global = local_unnamed_addr global i64 0, align 8
@global_arr = common local_unnamed_addr global [10 x i64] zeroinitializer, align 16
define void @foo() local_unnamed_addr !dbg !6 {
entry:
%0 = load i64, i64* getelementptr inbounds ([10 x i64], [10 x i64]* @global_arr, i64 0, i64 4), align 16
call void @llvm.dbg.value(metadata i64* getelementptr inbounds ([10 x i64], [10 x i64]* @global_arr, i64 0, i64 5), metadata !10, metadata !DIExpression()), !dbg !13
%1 = load i64, i64* getelementptr inbounds ([10 x i64], [10 x i64]* @global_arr, i64 0, i64 6), align 16
call void @llvm.dbg.value(metadata i64* getelementptr inbounds ([10 x i64], [10 x i64]* @global_arr, i64 0, i64 6), metadata !10, metadata !DIExpression()), !dbg !14
ret void
}
define void @bar() local_unnamed_addr !dbg !15 {
entry:
call void @llvm.dbg.value(metadata i64* getelementptr inbounds ([10 x i64], [10 x i64]* @global_arr, i64 0, i64 7), metadata !17, metadata !DIExpression()), !dbg !18
ret void
}
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #0
attributes #0 = { nounwind readnone speculatable }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!llvm.ident = !{!5}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2, nameTableKind: None)
!1 = !DIFile(filename: "uses.c", directory: "/")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{!"clang version 8.0.0"}
!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 6, type: !7, isLocal: false, isDefinition: true, scopeLine: 6, isOptimized: true, unit: !0, retainedNodes: !9)
!7 = !DISubroutineType(types: !8)
!8 = !{null}
!9 = !{!10}
!10 = !DILocalVariable(name: "local1", scope: !6, file: !1, line: 7, type: !11)
!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
!12 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
!13 = !DILocation(line: 8, column: 8, scope: !6)
!14 = !DILocation(line: 7, column: 9, scope: !6)
!15 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 12, type: !7, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, retainedNodes: !16)
!16 = !{!17}
!17 = !DILocalVariable(name: "local2", scope: !15, file: !1, line: 13, type: !11)
!18 = !DILocation(line: 14, column: 1, scope: !15)

15
llvm/tools/verify-uselistorder/verify-uselistorder.cpp
View File

@ -224,10 +224,16 @@ ValueMapping::ValueMapping(const Module &M) {
// Constants used by instructions.
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
for (const Value *Op : I.operands())
for (const Value *Op : I.operands()) {
// Look through a metadata wrapper.
if (const auto *MAV = dyn_cast<MetadataAsValue>(Op))
if (const auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
Op = VAM->getValue();
if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
isa<InlineAsm>(Op))
map(Op);
}
}
}
@ -500,10 +506,15 @@ static void changeUseLists(Module &M, Changer changeValueUseList) {
// Constants used by instructions.
for (BasicBlock &BB : F)
for (Instruction &I : BB)
for (Value *Op : I.operands())
for (Value *Op : I.operands()) {
// Look through a metadata wrapper.
if (auto *MAV = dyn_cast<MetadataAsValue>(Op))
if (auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
Op = VAM->getValue();
if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
isa<InlineAsm>(Op))
changeValueUseList(Op);
}
}
if (verifyModule(M, &errs()))