Index: include/llvm/IR/Value.h =================================================================== --- include/llvm/IR/Value.h +++ include/llvm/IR/Value.h @@ -239,6 +239,7 @@ private: void destroyValueName(); + void doRAUW(Value *New, bool NoMetadata); void setNameImpl(const Twine &Name); public: @@ -269,6 +270,12 @@ /// guaranteed to be empty. void replaceAllUsesWith(Value *V); + /// \brief Change non-metadata uses of this to point to a new Value. + /// + /// Go through the uses list for this definition and make each use point to + /// "V" instead of "this". This function skips metadata entries in the list. + void replaceNonMetadataUsesWith(Value *V); + /// replaceUsesOutsideBlock - Go through the uses list for this definition and /// make each use point to "V" instead of "this" when the use is outside the /// block. 'This's use list is expected to have at least one element. Index: lib/IR/Value.cpp =================================================================== --- lib/IR/Value.cpp +++ lib/IR/Value.cpp @@ -367,7 +367,7 @@ } #endif // NDEBUG -void Value::replaceAllUsesWith(Value *New) { +void Value::doRAUW(Value *New, bool NoMetadata) { assert(New && "Value::replaceAllUsesWith() is invalid!"); assert(!contains(New, this) && "this->replaceAllUsesWith(expr(this)) is NOT valid!"); @@ -377,7 +377,7 @@ // Notify all ValueHandles (if present) that this value is going away. if (HasValueHandle) ValueHandleBase::ValueIsRAUWd(this, New); - if (isUsedByMetadata()) + if (!NoMetadata && isUsedByMetadata()) ValueAsMetadata::handleRAUW(this, New); while (!use_empty()) { @@ -398,6 +398,14 @@ BB->replaceSuccessorsPhiUsesWith(cast(New)); } +void Value::replaceAllUsesWith(Value *New) { + doRAUW(New, false /* NoMetadata */); +} + +void Value::replaceNonMetadataUsesWith(Value *New) { + doRAUW(New, true /* NoMetadata */); +} + // Like replaceAllUsesWith except it does not handle constants or basic blocks. // This routine leaves uses within BB. void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) { Index: lib/Transforms/Scalar/BDCE.cpp =================================================================== --- lib/Transforms/Scalar/BDCE.cpp +++ lib/Transforms/Scalar/BDCE.cpp @@ -55,7 +55,7 @@ // undef, poison, etc. Value *Zero = ConstantInt::get(I.getType(), 0); ++NumSimplified; - I.replaceAllUsesWith(Zero); + I.replaceNonMetadataUsesWith(Zero); Changed = true; } if (!DB.isInstructionDead(&I)) Index: test/Transforms/BDCE/dbg-multipleuses.ll =================================================================== --- /dev/null +++ test/Transforms/BDCE/dbg-multipleuses.ll @@ -0,0 +1,47 @@ +; Test that BDCE doesn't destroy llvm.dbg.value's argument. +; RUN: opt -bdce %s -S | FileCheck %s + +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +; CHECK: define void @f() +; CHECK-NEXT: entry: +; CHECK-NEXT: tail call void (...) @h() +; CHECK-NEXT: %[[CALL:.*]] = tail call i32 (...) @g() +; CHECK-NEXT: tail call void @llvm.dbg.value(metadata i32 %[[CALL:.*]] + +define void @f() !dbg !6 { +entry: + tail call void (...) @h(), !dbg !9 + %call = tail call i32 (...) @g(), !dbg !10 + tail call void @llvm.dbg.value(metadata i32 %call, i64 0, metadata !11, metadata !13), !dbg !14 + %patatino = xor i32 %call, %call + tail call void (...) @h(), !dbg !15 + ret void, !dbg !16 +} + +declare void @h(...) +declare i32 @g(...) +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4} +!llvm.ident = !{!5} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 288665) (llvm/trunk 288725)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2) +!1 = !DIFile(filename: "patatino.c", directory: "/home/davide/work/llvm/build-clang/bin") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = !{!"clang version 4.0.0 (trunk 288665) (llvm/trunk 288725)"} +!6 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 3, type: !7, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: false, unit: !0, variables: !2) +!7 = !DISubroutineType(types: !8) +!8 = !{null} +!9 = !DILocation(line: 4, column: 3, scope: !6) +!10 = !DILocation(line: 5, column: 11, scope: !6) +!11 = !DILocalVariable(name: "a", scope: !6, file: !1, line: 5, type: !12) +!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!13 = !DIExpression() +!14 = !DILocation(line: 5, column: 7, scope: !6) +!15 = !DILocation(line: 6, column: 3, scope: !6) +!16 = !DILocation(line: 7, column: 1, scope: !6)