Index: lib/CodeGen/LiveDebugVariables.cpp =================================================================== --- lib/CodeGen/LiveDebugVariables.cpp +++ lib/CodeGen/LiveDebugVariables.cpp @@ -662,12 +662,12 @@ continue; } - // For physregs, use the live range of the first regunit as a guide. - unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI); - LiveRange *LR = &LIS.getRegUnit(Unit); - const VNInfo *VNI = LR->getVNInfoAt(Idx); - // Don't track copies from physregs, it is too expensive. - extendDef(Idx, LocNo, LR, VNI, nullptr, LIS); + // For physregs, we only mark the start slot idx. DwarfDebug will see it + // as if the DBG_VALUE is valid up until the end of the basic block, or + // the next def of the physical register. So we do not need to extend the + // range. It might actually happen that the DBG_VALUE is the last use of + // the physical register (e.g. if this is an unused input argument to a + // function). } // Erase all the undefs. Index: test/DebugInfo/MIR/X86/live-debug-vars-unused-arg.mir =================================================================== --- /dev/null +++ test/DebugInfo/MIR/X86/live-debug-vars-unused-arg.mir @@ -0,0 +1,175 @@ +# RUN: llc -O1 -start-before=greedy -stop-after=virtregrewriter -o /dev/null %s -debug-only=livedebugvars 2>&1 | FileCheck -check-prefix=CHECKDBG %s +# RUN: llc -O1 -start-before=greedy -stop-after=virtregrewriter -o - %s | FileCheck -check-prefix=CHECKMIR %s + +# REQUIRES: asserts + +# This test case was generated by using the following c program: +# extern void foo(int, int); +# +# int bar[2] = {1, 2}; +# +# int main(int argc, char** argv) +# { +# int a0 = bar[0]; +# int a1 = bar[1]; +# foo(a0, a1); +# return 0; +# } +# +# It was compiled with -g and -O1, and the mir was dumped before ra greedy. + +--- | + ; ModuleID = 'live-debug-vars-unused-arg.ll' + source_filename = "live-debug-vars-unused-arg.c" + target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + target triple = "x86_64-unknown-linux-gnu" + + @bar = local_unnamed_addr global [2 x i32] [i32 1, i32 2], align 4, !dbg !0 + + ; Function Attrs: nounwind uwtable + define i32 @main(i32 %argc, i8** nocapture readnone %argv) local_unnamed_addr #0 !dbg !14 { + entry: + tail call void @llvm.dbg.value(metadata i32 %argc, metadata !21, metadata !DIExpression()), !dbg !25 + tail call void @llvm.dbg.value(metadata i8** %argv, metadata !22, metadata !DIExpression()), !dbg !26 + %0 = load i32, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @bar, i64 0, i64 0), align 4, !dbg !27, !tbaa !28 + tail call void @llvm.dbg.value(metadata i32 %0, metadata !23, metadata !DIExpression()), !dbg !32 + %1 = load i32, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @bar, i64 0, i64 1), align 4, !dbg !33, !tbaa !28 + tail call void @llvm.dbg.value(metadata i32 %1, metadata !24, metadata !DIExpression()), !dbg !34 + tail call void @foo(i32 %0, i32 %1) #2, !dbg !35 + ret i32 0, !dbg !36 + } + + declare void @foo(i32, i32) local_unnamed_addr + + ; Function Attrs: nounwind readnone speculatable + declare void @llvm.dbg.value(metadata, metadata, metadata) #1 + + ; Function Attrs: nounwind + declare void @llvm.stackprotector(i8*, i8**) #2 + + attributes #0 = { nounwind uwtable } + attributes #1 = { nounwind readnone speculatable } + attributes #2 = { nounwind } + + !llvm.dbg.cu = !{!2} + !llvm.module.flags = !{!10, !11, !12} + !llvm.ident = !{!13} + + !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression()) + !1 = distinct !DIGlobalVariable(name: "bar", scope: !2, file: !3, line: 3, type: !6, isLocal: false, isDefinition: true) + !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 6.0.0 (trunk 313866) (llvm/trunk 313875)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5) + !3 = !DIFile(filename: "live-debug-vars-unused-arg.c", directory: "/repo/uabbpet/master") + !4 = !{} + !5 = !{!0} + !6 = !DICompositeType(tag: DW_TAG_array_type, baseType: !7, size: 64, elements: !8) + !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) + !8 = !{!9} + !9 = !DISubrange(count: 2) + !10 = !{i32 2, !"Dwarf Version", i32 4} + !11 = !{i32 2, !"Debug Info Version", i32 3} + !12 = !{i32 1, !"wchar_size", i32 4} + !13 = !{!"clang version 6.0.0 (trunk 313866) (llvm/trunk 313875)"} + !14 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 5, type: !15, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !2, variables: !20) + !15 = !DISubroutineType(types: !16) + !16 = !{!7, !7, !17} + !17 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !18, size: 64) + !18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64) + !19 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char) + !20 = !{!21, !22, !23, !24} + !21 = !DILocalVariable(name: "argc", arg: 1, scope: !14, file: !3, line: 5, type: !7) + !22 = !DILocalVariable(name: "argv", arg: 2, scope: !14, file: !3, line: 5, type: !17) + !23 = !DILocalVariable(name: "a0", scope: !14, file: !3, line: 7, type: !7) + !24 = !DILocalVariable(name: "a1", scope: !14, file: !3, line: 8, type: !7) + !25 = !DILocation(line: 5, column: 14, scope: !14) + !26 = !DILocation(line: 5, column: 27, scope: !14) + !27 = !DILocation(line: 7, column: 12, scope: !14) + !28 = !{!29, !29, i64 0} + !29 = !{!"int", !30, i64 0} + !30 = !{!"omnipotent char", !31, i64 0} + !31 = !{!"Simple C/C++ TBAA"} + !32 = !DILocation(line: 7, column: 7, scope: !14) + !33 = !DILocation(line: 8, column: 12, scope: !14) + !34 = !DILocation(line: 8, column: 7, scope: !14) + !35 = !DILocation(line: 9, column: 3, scope: !14) + !36 = !DILocation(line: 10, column: 3, scope: !14) + +... +--- +name: main +alignment: 4 +exposesReturnsTwice: false +legalized: false +regBankSelected: false +selected: false +tracksRegLiveness: true +registers: + - { id: 0, class: gr32, preferred-register: '' } + - { id: 1, class: gr64, preferred-register: '' } + - { id: 2, class: gr32, preferred-register: '' } + - { id: 3, class: gr32, preferred-register: '' } + - { id: 4, class: gr32, preferred-register: '' } +liveins: +frameInfo: + isFrameAddressTaken: false + isReturnAddressTaken: false + hasStackMap: false + hasPatchPoint: false + stackSize: 0 + offsetAdjustment: 0 + maxAlignment: 0 + adjustsStack: false + hasCalls: true + stackProtector: '' + maxCallFrameSize: 4294967295 + hasOpaqueSPAdjustment: false + hasVAStart: false + hasMustTailInVarArgFunc: false + savePoint: '' + restorePoint: '' +fixedStack: +stack: +constants: +body: | + bb.0.entry: + DBG_VALUE debug-use %edi, debug-use _, !21, !DIExpression(), debug-location !25 + DBG_VALUE debug-use %rsi, debug-use _, !22, !DIExpression(), debug-location !26 + %2 = MOV32rm %rip, 1, _, @bar, _, debug-location !27 :: (dereferenceable load 4 from `i32* getelementptr inbounds ([2 x i32], [2 x i32]* @bar, i64 0, i64 0)`, !tbaa !28) + DBG_VALUE debug-use %2, debug-use _, !23, !DIExpression(), debug-location !32 + %3 = MOV32rm %rip, 1, _, @bar + 4, _, debug-location !33 :: (dereferenceable load 4 from `i32* getelementptr inbounds ([2 x i32], [2 x i32]* @bar, i64 0, i64 1)`, !tbaa !28) + DBG_VALUE debug-use %3, debug-use _, !24, !DIExpression(), debug-location !34 + ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead %rsp, implicit-def dead %eflags, implicit %rsp, debug-location !35 + %edi = COPY %2, debug-location !35 + %esi = COPY %3, debug-location !35 + CALL64pcrel32 @foo, csr_64, implicit %rsp, implicit killed %edi, implicit killed %esi, implicit-def %rsp, debug-location !35 + ADJCALLSTACKUP64 0, 0, implicit-def dead %rsp, implicit-def dead %eflags, implicit %rsp, debug-location !35 + %eax = MOV32r0 implicit-def dead %eflags, debug-location !36 + RET 0, killed %eax, debug-location !36 + +... + +# Let's verify that the slot index ranges for the unused variables argc/argv, +# connected to physical regs %EDI and %RSI, does not overlap with the ranges +# for %vreg2 and %vreg3. The register allocator is actually allocating the +# virtual registers # to %EDI and %ESI, so the ranges for argc/argv should +# not cover the whole BB. +# +# CHECKDBG-LABEL: ********** EMITTING LIVE DEBUG VARIABLES ********** +# CHECKDBG-NEXT: !"argc,5" [0B;0e):0 Loc0=%EDI +# CHECKDBG-NEXT: [0B;0e):0 BB#0-160B +# CHECKDBG-NEXT: !"argv,5" [0B;0e):0 Loc0=%RSI +# CHECKDBG-NEXT: [0B;0e):0 BB#0-160B +# CHECKDBG-NEXT: !"a0,7" [16r;64r):0 Loc0=%vreg2 +# CHECKDBG-NEXT: [16r;64r):0 BB#0-160B +# CHECKDBG-NEXT: !"a1,8" [32r;80r):0 Loc0=%vreg3 +# CHECKDBG-NEXT: [32r;80r):0 BB#0-160B + +# Verify that we only get one DBG_VALUE for argc and one for argv. +# CHECKMIR: ![[ARGC:[0-9]+]] = !DILocalVariable(name: "argc", arg: 1 +# CHECKMIR: ![[ARGV:[0-9]+]] = !DILocalVariable(name: "argv", arg: 2 +# CHECKMIR: name: main +# CHECKMIR: body: +# CHECKMIR: DBG_VALUE debug-use %edi, debug-use _, ![[ARGC]] +# CHECKMIR: DBG_VALUE debug-use %rsi, debug-use _, ![[ARGV]] +# CHECKMIR-NOT: DBG_VALUE debug-use %{{.*}}, debug-use _, ![[ARGC]] +# CHECKMIR-NOT: DBG_VALUE debug-use %{{.*}}, debug-use _, ![[ARGV]] +