Index: llvm/lib/Transforms/Scalar/SROA.cpp =================================================================== --- llvm/lib/Transforms/Scalar/SROA.cpp +++ llvm/lib/Transforms/Scalar/SROA.cpp @@ -225,6 +225,7 @@ LLVM_DEBUG(dbgs() << " existing dbg.assign is: " << *DbgAssign << "\n"); auto *Expr = DbgAssign->getExpression(); + bool SetKillLocation = false; if (IsSplit) { std::optional BaseFragment = std::nullopt; @@ -252,11 +253,19 @@ // relative fragment too? NewFragment->OffsetInBits -= CurrentFragment->OffsetInBits; } - - auto E = DIExpression::createFragmentExpression( - Expr, NewFragment->OffsetInBits, NewFragment->SizeInBits); - assert(E && "Failed to create fragment expr!"); - Expr = *E; + // Add the new fragment info to the existing expression if possible. + if (auto E = DIExpression::createFragmentExpression( + Expr, NewFragment->OffsetInBits, NewFragment->SizeInBits)) { + Expr = *E; + } else { + // Otherwise, add the new fragment info to an empty expression and + // discard the value component of this dbg.assign as the value cannot + // be computed with the new fragment. + Expr = *DIExpression::createFragmentExpression( + DIExpression::get(Expr->getContext(), std::nullopt), + NewFragment->OffsetInBits, NewFragment->SizeInBits); + SetKillLocation = true; + } } } @@ -281,7 +290,8 @@ // This should be a very rare situation as it requires the value being // stored to differ from the dbg.assign (i.e., the value has been // represented differently in the debug intrinsic for some reason). - if (DbgAssign->hasArgList() && Value) + SetKillLocation |= DbgAssign->hasArgList() && Value; + if (SetKillLocation) NewAssign->setKillLocation(); // We could use more precision here at the cost of some additional (code) Index: llvm/test/DebugInfo/Generic/assignment-tracking/sroa/fail-fragment.ll =================================================================== --- /dev/null +++ llvm/test/DebugInfo/Generic/assignment-tracking/sroa/fail-fragment.ll @@ -0,0 +1,64 @@ +; RUN: opt -passes=sroa -S %s -o - \ +; RUN: | FileCheck %s --implicit-check-not="call void @llvm.dbg" + +;; Check that a dbg.assign for a promoted variable becomes a kill location if +;; it used a fragment that can't be split (the first check directive below). +;; NOTE: If createFragmentExpression gets smarter it may be necessary to create +;; a new test case. + +; CHECK: if.then: +; CHECK: call void @llvm.dbg.value(metadata i32 poison, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)) +; CHECK: call void @llvm.dbg.value(metadata i32 %{{.*}}, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32)) + +; CHECK: if.else: +; CHECK: dbg.value(metadata i32 2, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)) +; CHECK: dbg.value(metadata i32 0, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32)) + +; CHECK: end: +; CHECK: call void @llvm.dbg.value(metadata i32 %{{.*}}, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)) + +declare i64 @get_i64() + +define internal fastcc i64 @fun() !dbg !18 { +entry: + %codepoint = alloca i64, align 4, !DIAssignID !27 + call void @llvm.dbg.assign(metadata i1 poison, metadata !15, metadata !DIExpression(), metadata !27, metadata ptr %codepoint, metadata !DIExpression()), !dbg !26 + %0 = call i64 @get_i64() #2 + %1 = add i64 %0, 1 + %cmp = icmp ugt i64 %1, 100 + br i1 %cmp, label %if.then, label %if.else + +if.then: + store i64 %1, ptr %codepoint, align 4, !DIAssignID !25 + call void @llvm.dbg.assign(metadata i64 %1, metadata !15, metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value), metadata !25, metadata ptr %codepoint, metadata !DIExpression()), !dbg !26 + br label %end + +if.else: + store i64 2, ptr %codepoint, align 4, !DIAssignID !28 + call void @llvm.dbg.assign(metadata i32 2, metadata !15, metadata !DIExpression(), metadata !28, metadata ptr %codepoint, metadata !DIExpression()), !dbg !26 + br label %end + +end: + %r = load i32, ptr %codepoint + %rr = zext i32 %r to i64 + ret i64 %rr +} + +declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!13, !14} + +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 17.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, imports: !2, splitDebugInlining: false, nameTableKind: None) +!1 = !DIFile(filename: "reduce.cpp", directory: "/") +!2 = !{} +!13 = !{i32 2, !"Debug Info Version", i32 3} +!14 = !{i32 7, !"debug-info-assignment-tracking", i1 true} +!15 = !DILocalVariable(name: "codepoint", scope: !18, file: !1, line: 10, type: !24) +!18 = distinct !DISubprogram(name: "fun", linkageName: "fun", scope: !1, file: !1, line: 4, type: !19, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2) +!19 = distinct !DISubroutineType(types: !2) +!24 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned) +!25 = distinct !DIAssignID() +!26 = !DILocation(line: 0, scope: !18) +!27 = distinct !DIAssignID() +!28 = distinct !DIAssignID()