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LowerDbgDeclare: ignore dbg.declares for allocas with volatile access
There is no point in lowering a dbg.declare describing an alloca that has volatile loads or stores as users, since the alloca cannot be elided. Lowering the dbg.declare will result in larger debug info that may also have worse coverage than just describing the alloca. rdar://problem/34496278 llvm-svn: 327092
This commit is contained in:
Adrian Prantl
parent
c1410ce6f6
commit
45e666cd89
@ -1322,25 +1322,36 @@ bool llvm::LowerDbgDeclare(Function &F) {
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// stored on the stack, while the dbg.declare can only describe
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// the stack slot (and at a lexical-scope granularity). Later
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// passes will attempt to elide the stack slot.
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if (AI && !isArray(AI)) {
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for (auto &AIUse : AI->uses()) {
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User *U = AIUse.getUser();
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if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
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if (AIUse.getOperandNo() == 1)
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ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
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} else if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
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ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
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} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// This is a call by-value or some other instruction that
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// takes a pointer to the variable. Insert a *value*
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// intrinsic that describes the alloca.
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DIB.insertDbgValueIntrinsic(AI, DDI->getVariable(),
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DDI->getExpression(), DDI->getDebugLoc(),
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CI);
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}
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if (!AI || isArray(AI))
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continue;
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// A volatile load/store means that the alloca can't be elided anyway.
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if (llvm::any_of(AI->users(), [](User *U) -> bool {
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if (LoadInst *LI = dyn_cast<LoadInst>(U))
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return LI->isVolatile();
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if (StoreInst *SI = dyn_cast<StoreInst>(U))
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return SI->isVolatile();
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return false;
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}))
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continue;
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for (auto &AIUse : AI->uses()) {
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User *U = AIUse.getUser();
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if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
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if (AIUse.getOperandNo() == 1)
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ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
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} else if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
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ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
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} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// This is a call by-value or some other instruction that
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// takes a pointer to the variable. Insert a *value*
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// intrinsic that describes the alloca.
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DIB.insertDbgValueIntrinsic(AI, DDI->getVariable(),
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DDI->getExpression(), DDI->getDebugLoc(),
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CI);
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}
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DDI->eraseFromParent();
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}
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DDI->eraseFromParent();
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}
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return true;
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}
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83
test/DebugInfo/Generic/volatile-alloca.ll
Normal file
83
test/DebugInfo/Generic/volatile-alloca.ll
Normal file
@ -0,0 +1,83 @@
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; RUN: opt -mem2reg -instcombine %s -o - -S | FileCheck %s
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;
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; Test that a dbg.declare describing am alloca with volatile
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; load/stores is not lowered into a dbg.value, since the alloca won't
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; be elided anyway.
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;
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; Generated from:
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;
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; unsigned long long g();
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; void h(unsigned long long);
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; void f() {
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; volatile unsigned long long v = g();
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; if (v == 0)
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; g();
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; h(v);
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; }
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; CHECK: alloca i64
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; CHECK-NOT: call void @llvm.dbg.value
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; CHECK: call void @llvm.dbg.declare
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; CHECK-NOT: call void @llvm.dbg.value
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source_filename = "volatile.c"
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; Function Attrs: nounwind optsize ssp uwtable
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define void @f() local_unnamed_addr #0 !dbg !8 {
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%1 = alloca i64, align 8
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%2 = bitcast i64* %1 to i8*, !dbg !15
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call void @llvm.lifetime.start.p0i8(i64 8, i8* %2), !dbg !15
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call void @llvm.dbg.declare(metadata i64* %1, metadata !12, metadata !DIExpression()), !dbg !15
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%3 = call i64 (...) @g() #4, !dbg !15
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store volatile i64 %3, i64* %1, align 8, !dbg !15
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%4 = load volatile i64, i64* %1, align 8, !dbg !15
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%5 = icmp eq i64 %4, 0, !dbg !15
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br i1 %5, label %6, label %8, !dbg !15
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; <label>:6: ; preds = %0
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%7 = call i64 (...) @g() #4, !dbg !15
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br label %8, !dbg !15
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; <label>:8: ; preds = %6, %0
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%9 = load volatile i64, i64* %1, align 8, !dbg !15
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call void @h(i64 %9) #4, !dbg !15
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call void @llvm.lifetime.end.p0i8(i64 8, i8* %2), !dbg !15
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ret void, !dbg !15
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}
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; Function Attrs: argmemonly nounwind
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declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #1
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
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; Function Attrs: optsize
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declare i64 @g(...) local_unnamed_addr #3
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; Function Attrs: optsize
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declare void @h(i64) local_unnamed_addr #3
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; Function Attrs: argmemonly nounwind
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declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #1
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attributes #0 = { nounwind optsize ssp uwtable }
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attributes #1 = { argmemonly nounwind }
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attributes #2 = { nounwind readnone speculatable }
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attributes #3 = { optsize }
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attributes #4 = { optsize }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
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!1 = !DIFile(filename: "volatile.c", directory: "/")
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!8 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 3, type: !9, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0, variables: !11)
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!9 = !DISubroutineType(types: !10)
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!10 = !{null}
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!11 = !{!12}
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!12 = !DILocalVariable(name: "v", scope: !8, file: !1, line: 4, type: !13)
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!13 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !14)
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!14 = !DIBasicType(name: "long long unsigned int", size: 64, encoding: DW_ATE_unsigned)
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!15 = !DILocation(line: 4, column: 3, scope: !8)
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@ -13,6 +13,7 @@ declare void @llvm.dbg.value(metadata, metadata, metadata) #0
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define void @julia_fastshortest_6256() #1 {
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top:
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%cp = alloca %foo, align 8
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%sink = alloca %foo, align 8
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call void @llvm.dbg.declare(metadata %foo* %cp, metadata !1, metadata !16), !dbg !17
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br i1 undef, label %idxend, label %fail
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@ -21,9 +22,10 @@ fail: ; preds = %top
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idxend: ; preds = %top
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; CHECK-NOT: call void @llvm.dbg.value(metadata %foo* %cp,
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%0 = load volatile %foo, %foo* %cp, align 8
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; CHECK: call void @llvm.dbg.value(metadata %foo %0,
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store volatile %foo %0, %foo* undef, align 8
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%0 = load %foo, %foo* %cp, align 8
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store volatile %foo %0, %foo *%sink, align 8
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; CHECK: call void @llvm.dbg.value(metadata %foo %
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store %foo %0, %foo* undef, align 8
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ret void
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}
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