Index: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp =================================================================== --- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp +++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp @@ -1436,7 +1436,10 @@ for (MachineOperand &UseMO : MRI->use_operands(SrcReg)) { MachineInstr *UseMI = UseMO.getParent(); if (UseMI->isDebugValue()) { - UseMO.setReg(DstReg); + if (TargetRegisterInfo::isPhysicalRegister(DstReg)) + UseMO.substPhysReg(DstReg, *TRI); + else + 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); Index: llvm/trunk/test/CodeGen/X86/coalesce-dbg-value-subreg-rewrite.mir =================================================================== --- llvm/trunk/test/CodeGen/X86/coalesce-dbg-value-subreg-rewrite.mir +++ llvm/trunk/test/CodeGen/X86/coalesce-dbg-value-subreg-rewrite.mir @@ -0,0 +1,51 @@ +# RUN: llc -O0 -mtriple x86_64-pc-linux-gnu -run-pass simple-register-coalescing -verify-coalescing -o - %s | FileCheck %s + +--- | + define i16 @main() { + entry: + call void @llvm.dbg.value(metadata i8 0, metadata !11, metadata !DIExpression()), !dbg !13 + ret i16 0 + } + + ; Function Attrs: nounwind readnone speculatable + declare void @llvm.dbg.value(metadata, metadata, metadata) + + !llvm.dbg.cu = !{!0} + !llvm.module.flags = !{!3, !4, !5} + !llvm.ident = !{!6} + + !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2) + !1 = !DIFile(filename: "tmp.c", directory: "") + !2 = !{} + !3 = !{i32 2, !"Dwarf Version", i32 4} + !4 = !{i32 2, !"Debug Info Version", i32 3} + !5 = !{i32 1, !"wchar_size", i32 1} + !6 = !{!"clang"} + !7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 4, type: !8, isLocal: false, isDefinition: true, scopeLine: 4, isOptimized: false, unit: !0, retainedNodes: !2) + !8 = !DISubroutineType(types: !9) + !9 = !{!10} + !10 = !DIBasicType(name: "int", size: 16, encoding: DW_ATE_signed) + !11 = !DILocalVariable(name: "c", scope: !7, file: !1, line: 5, type: !12) + !12 = !DIBasicType(name: "mytype", size: 16) + !13 = !DILocation(line: 5, column: 11, scope: !7) + +... +--- +name: main +tracksRegLiveness: true +body: | + bb.0.entry: + %0:gr16_abcd = MOV16ri 0 + DBG_VALUE debug-use %0.sub_8bit:gr16_abcd, debug-use $noreg, !11, !DIExpression(), debug-location !13 + undef %6.sub_8bit:gr16_abcd = COPY killed %0.sub_8bit + dead $dx = COPY killed %6 + +... + +# Verify that we get $dl in the DBG_VALUE (and not $dx.sub_8bit as we used to +# do before the bugfix, which resulted in "Bad machine code: Illegal +# subregister index for physical register"). +# +# CHECK: bb.0.entry: +# CHECK-NEXT: $dx = MOV16ri 0 +# CHECK-NEXT: DBG_VALUE debug-use $dl,