Index: lib/CodeGen/RegisterCoalescer.cpp =================================================================== --- lib/CodeGen/RegisterCoalescer.cpp +++ lib/CodeGen/RegisterCoalescer.cpp @@ -1319,6 +1319,9 @@ MachineInstr *UseMI = UseMO.getParent(); if (UseMI->isDebugValue()) { UseMO.setReg(DstReg); + // Move the debug value directly after the def of the rematerialized + // value in DstReg. + MBB->splice(std::next(NewMI.getIterator()), UseMI->getParent(), UseMI); DEBUG(dbgs() << "\t\tupdated: " << *UseMI); } } Index: test/DebugInfo/MIR/X86/regcoalescer.mir =================================================================== --- /dev/null +++ test/DebugInfo/MIR/X86/regcoalescer.mir @@ -0,0 +1,50 @@ +# RUN: llc -O1 -filetype=asm -mtriple x86_64-unknown-linux-gnu -mcpu=x86-64 -o - %s -start-before=simple-register-coalescing -stop-after=simple-register-coalescing | FileCheck %s + +--- | + target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + target triple = "x86_64-unknown-linux-gnu" + + define i32 @main() local_unnamed_addr !dbg !14 { + entry: + %shl = shl i32 undef, undef, !dbg !19 + tail call void @llvm.dbg.value(metadata i32 %shl, metadata !18, metadata !DIExpression()), !dbg !20 + ret i32 %shl, !dbg !21 + } + + declare void @llvm.dbg.value(metadata, metadata, metadata) + + !llvm.dbg.cu = !{!0} + !llvm.module.flags = !{!12, !13} + + !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2) + !1 = !DIFile(filename: "bar.c", directory: "") + !2 = !{} + !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) + !12 = !{i32 2, !"Debug Info Version", i32 3} + !13 = !{i32 1, !"wchar_size", i32 4} + !14 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 12, type: !15, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, variables: !17) + !15 = !DISubroutineType(types: !16) + !16 = !{!7} + !17 = !{!18} + !18 = !DILocalVariable(name: "bazinga", scope: !14, file: !1, line: 13, type: !7) + !19 = !DILocation(line: 14, column: 11, scope: !14) + !20 = !DILocation(line: 13, column: 7, scope: !14) + !21 = !DILocation(line: 16, column: 3, scope: !14) + +... +--- +name: main +alignment: 4 +registers: + - { id: 0, class: gr32, preferred-register: '' } +body: | + bb.0.entry: + %0 = MOV32r0 implicit-def dead %eflags, debug-location !19 + DBG_VALUE debug-use %0, debug-use _, !18, !DIExpression(), debug-location !20 + %eax = COPY killed %0, debug-location !21 + RET 0, killed %eax, debug-location !21 + +... + +# CHECK: %eax = MOV32r0 +# CHECK-NEXT: DBG_VALUE debug-use %eax