[llvm] r239380 - [DWARF] Fix a few corner cases in expression emission
David Blaikie
dblaikie at gmail.com
Mon Jun 8 21:05:26 PDT 2015
Looks like this might've caused:
http://lab.llvm.org:8011/builders/clang-x86_64-ubuntu-gdb-75/builds/22562
On Mon, Jun 8, 2015 at 6:54 PM, Keno Fischer <kfischer at college.harvard.edu>
wrote:
> Author: kfischer
> Date: Mon Jun 8 20:53:59 2015
> New Revision: 239380
>
> URL: http://llvm.org/viewvc/llvm-project?rev=239380&view=rev
> Log:
> [DWARF] Fix a few corner cases in expression emission
>
> Summary: I noticed an object file with `DW_OP_reg4 DW_OP_breg4 0` as a
> DWARF expression,
> which I traced to a missing break (and `++I`) in this code snippet.
> While I was at it, I also added support for a few other corner cases
> along the same lines that I could think of.
>
> Test Plan: Hand-crafted test case to exercises these cases is included.
>
> Reviewers: echristo, dblaikie, aprantl
>
> Reviewed By: aprantl
>
> Subscribers: llvm-commits
>
> Differential Revision: http://reviews.llvm.org/D10302
>
> Added:
> llvm/trunk/test/DebugInfo/expressions.ll
> Modified:
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=239380&r1=239379&r2=239380&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Mon Jun 8 20:53:59
> 2015
> @@ -1562,6 +1562,8 @@ void DwarfDebug::emitDebugLoc() {
> Asm->OutStreamer->EmitLabel(List.Label);
> const DwarfCompileUnit *CU = List.CU;
> for (const auto &Entry : DebugLocs.getEntries(List)) {
> + if (Entry.BeginSym == Entry.EndSym)
> + continue;
> // Set up the range. This range is relative to the entry point of
> the
> // compile unit. This is a hard coded 0 for low_pc when we're
> emitting
> // ranges, or the DW_AT_low_pc on the compile unit otherwise.
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp?rev=239380&r1=239379&r2=239380&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp Mon Jun 8
> 20:53:59 2015
> @@ -65,6 +65,11 @@ void DwarfExpression::AddShr(unsigned Sh
> EmitOp(dwarf::DW_OP_shr);
> }
>
> +void DwarfExpression::AddOpStackValue() {
> + if (DwarfVersion >= 4)
> + EmitOp(dwarf::DW_OP_stack_value);
> +}
> +
> bool DwarfExpression::AddMachineRegIndirect(unsigned MachineReg, int
> Offset) {
> if (isFrameRegister(MachineReg)) {
> // If variable offset is based in frame register then use fbreg.
> @@ -172,16 +177,14 @@ void DwarfExpression::AddSignedConstant(
> // value, so the producers and consumers started to rely on heuristics
> // to disambiguate the value vs. location status of the expression.
> // See PR21176 for more details.
> - if (DwarfVersion >= 4)
> - EmitOp(dwarf::DW_OP_stack_value);
> + AddOpStackValue();
> }
>
> void DwarfExpression::AddUnsignedConstant(unsigned Value) {
> EmitOp(dwarf::DW_OP_constu);
> EmitUnsigned(Value);
> // cf. comment in DwarfExpression::AddSignedConstant().
> - if (DwarfVersion >= 4)
> - EmitOp(dwarf::DW_OP_stack_value);
> + AddOpStackValue();
> }
>
> static unsigned getOffsetOrZero(unsigned OffsetInBits,
> @@ -212,15 +215,30 @@ bool DwarfExpression::AddMachineRegExpre
> getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
> }
> case dwarf::DW_OP_plus: {
> - // [DW_OP_reg,Offset,DW_OP_plus,DW_OP_deref] --> [DW_OP_breg,Offset].
> auto N = I.getNext();
> + unsigned Offset = I->getArg(0);
> + // First combine all DW_OP_plus until we hit either a DW_OP_deref or a
> + // DW_OP_bit_piece
> + while (N != E && N->getOp() == dwarf::DW_OP_plus) {
> + Offset += N->getArg(0);
> + ++I;
> + N = I.getNext();
> + }
> if (N != E && N->getOp() == dwarf::DW_OP_deref) {
> - unsigned Offset = I->getArg(0);
> + // [DW_OP_reg,Offset,DW_OP_plus,DW_OP_deref] -->
> [DW_OP_breg,Offset].
> ValidReg = AddMachineRegIndirect(MachineReg, Offset);
> std::advance(I, 2);
> - break;
> - } else
> - ValidReg = AddMachineRegPiece(MachineReg);
> + } else {
> + assert ((N == E) || (N->getOp() == dwarf::DW_OP_bit_piece));
> + if (Offset == 0) {
> + ValidReg = AddMachineRegPiece(MachineReg);
> + } else {
> + ValidReg = AddMachineRegIndirect(MachineReg, Offset);
> + AddOpStackValue();
> + }
> + ++I;
> + }
> + break;
> }
> case dwarf::DW_OP_deref: {
> // [DW_OP_reg,DW_OP_deref] --> [DW_OP_breg].
> @@ -237,6 +255,7 @@ bool DwarfExpression::AddMachineRegExpre
>
> // Emit remaining elements of the expression.
> AddExpression(I, E, PieceOffsetInBits);
> +
> return true;
> }
>
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h?rev=239380&r1=239379&r2=239380&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.h Mon Jun 8
> 20:53:59 2015
> @@ -83,6 +83,9 @@ public:
> bool AddMachineRegPiece(unsigned MachineReg, unsigned PieceSizeInBits =
> 0,
> unsigned PieceOffsetInBits = 0);
>
> + /// Emit a DW_OP_stack_value
> + void AddOpStackValue();
> +
> /// Emit a signed constant.
> void AddSignedConstant(int Value);
> /// Emit an unsigned constant.
>
> Added: llvm/trunk/test/DebugInfo/expressions.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/expressions.ll?rev=239380&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/expressions.ll (added)
> +++ llvm/trunk/test/DebugInfo/expressions.ll Mon Jun 8 20:53:59 2015
> @@ -0,0 +1,110 @@
> +; REQUIRES: object-emission
> +; RUN: %llc_dwarf -mtriple x86_64-apple-darwin14.0.0-elf -filetype=obj %s
> -o %t
> +; RUN: %llc_dwarf -mtriple x86_64-apple-darwin14.0.0-elf -O0
> -filetype=obj %s -o %t0
> +; RUN: llvm-dwarfdump -debug-dump=loc %t | FileCheck %s
> +; RUN: llvm-dwarfdump -debug-dump=loc %t0 | FileCheck -check-prefix
> CHECK-O0 %s
> +
> +; CHECK: 0x00000000: Beginning address offset: 0x0000000000000000
> +; CHECK: Ending address offset: 0x[[END:[0-9a-f]+]]
> +; CHECK: Location description:
> +; CHECK-NOT: 75 00 55
> +; CHECK-SAME: 55
> +; CHECK: 0x00000023: Beginning address offset: 0x0000000000000000
> +; CHECK: Ending address offset: 0x{{.*}}[[END]]
> +; CHECK: Location description: 75 08 9f
> +; CHECK: 0x00000048: Beginning address offset: 0x0000000000000000
> +; CHECK: Ending address offset: 0x{{.*}}[[END]]
> +; CHECK: Location description: 75 10 9f
> +; CHECK: 0x0000006d: Beginning address offset: 0x0000000000000000
> +; CHECK: Ending address offset: 0x{{.*}}[[END]]
> +; CHECK: Location description: 75 18
> +
> +
> +; CHECK-O0: 0x00000000: Beginning address offset: 0x0000000000000000
> +; CHECK-O0: Ending address offset: 0x000000000000001b
> +; CHECK-O0: Location description: 55
> +; CHECK-O0: Beginning address offset: 0x000000000000001b
> +; CHECK-O0: Ending address offset: 0x0000000000000024
> +; CHECK-O0: Location description: 54
> +; CHECK-O0: Beginning address offset: 0x0000000000000024
> +; CHECK-O0: Ending address offset: 0x0000000000000025
> +; CHECK-O0: Location description: 77 78 23 00
> +; CHECK-O0: 0x0000004c: Beginning address offset: 0x0000000000000000
> +; CHECK-O0: Ending address offset: 0x000000000000001b
> +; CHECK-O0: Location description: 75 08 9f
> +; CHECK-O0: Beginning address offset: 0x000000000000001b
> +; CHECK-O0: Ending address offset: 0x0000000000000024
> +; CHECK-O0: Location description: 74 08 9f
> +; CHECK-O0: Beginning address offset: 0x0000000000000024
> +; CHECK-O0: Ending address offset: 0x0000000000000025
> +; CHECK-O0: Location description: 77 78 23 08
> +; CHECK-O0: 0x0000009c: Beginning address offset: 0x0000000000000000
> +; CHECK-O0: Ending address offset: 0x000000000000001b
> +; CHECK-O0: Location description: 75 10 9f
> +; CHECK-O0: Beginning address offset: 0x000000000000001b
> +; CHECK-O0: Ending address offset: 0x0000000000000024
> +; CHECK-O0: Location description: 74 10 9f
> +; CHECK-O0: Beginning address offset: 0x0000000000000024
> +; CHECK-O0: Ending address offset: 0x0000000000000025
> +; CHECK-O0: Location description: 77 78 23 08 23 08
> +; CHECK-O0: 0x000000ee: Beginning address offset: 0x0000000000000000
> +; CHECK-O0: Ending address offset: 0x000000000000001b
> +; CHECK-O0: Location description: 75 18
> +; CHECK-O0: Beginning address offset: 0x000000000000001b
> +; CHECK-O0: Ending address offset: 0x0000000000000024
> +; CHECK-O0: Location description: 74 18
> +; CHECK-O0: Beginning address offset: 0x0000000000000024
> +; CHECK-O0: Ending address offset: 0x0000000000000025
> +; CHECK-O0: Location description: 77 78 23 10 23 08 06
> +
> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #0
> +
> +define float @foo(float* %args, float *%args2)
> +{
> + call void @llvm.dbg.value(metadata float* %args, i64 0, metadata !11,
> metadata !12), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args, i64 0, metadata !13,
> metadata !14), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args, i64 0, metadata !15,
> metadata !16), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args, i64 0, metadata !17,
> metadata !18), !dbg !19
> + %a = load float, float* %args, !dbg !19
> + %bptr = getelementptr float, float* %args, i32 1, !dbg !19
> + %b = load float, float* %bptr, !dbg !19
> + %cptr = getelementptr float, float* %args, i32 2, !dbg !19
> + %c = load float, float* %cptr, !dbg !19
> + %dptr = getelementptr float, float* %args, i32 3, !dbg !19
> + %d = load float, float* %dptr, !dbg !19
> + %ret1 = fadd float %a, %b, !dbg !19
> + %ret2 = fadd float %c, %d, !dbg !19
> + call void @llvm.dbg.value(metadata float* %args2, i64 0, metadata
> !11, metadata !12), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args2, i64 0, metadata
> !13, metadata !14), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args2, i64 0, metadata
> !15, metadata !16), !dbg !19
> + call void @llvm.dbg.value(metadata float* %args2, i64 0, metadata
> !17, metadata !18), !dbg !19
> + %ret = fsub float %ret1, %ret2, !dbg !19
> + ret float %ret, !dbg !19
> +}
> +
> +attributes #0 = { nounwind readnone }
> +
> +!llvm.module.flags = !{!0, !1}
> +!llvm.dbg.cu = !{!2}
> +
> +!0 = !{i32 2, !"Dwarf Version", i32 4}
> +!1 = !{i32 1, !"Debug Info Version", i32 3}
> +
> +!2 = !DICompileUnit(language: DW_LANG_C89, file: !3, producer: "byHand",
> isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !4,
> retainedTypes: !4, subprograms: !5, globals: !4, imports: !4)
> +!3 = !DIFile(filename: "expressions", directory: ".")
> +!4 = !{}
> +!5 = !{!6}
> +!6 = !DISubprogram(name: "foo", linkageName: "foo", scope: null, file:
> !3, type: !7, isLocal: false, isDefinition: true, isOptimized: true,
> function: float (float*, float*)* @foo, variables: !4)
> +!7 = !DISubroutineType(types: !8)
> +!8 = !{!10, !10}
> +!9 = !DIBasicType(name: "float", size: 4, align: 4, encoding:
> DW_ATE_float)
> +!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 64,
> align: 64)
> +!11 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "a", arg: 1,
> scope: !6, file: !3, line: 1, type: !10)
> +!12 = !DIExpression(DW_OP_plus, 0)
> +!13 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "b", arg: 2,
> scope: !6, file: !3, line: 1, type: !10)
> +!14 = !DIExpression(DW_OP_plus, 8)
> +!15 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "c", arg: 3,
> scope: !6, file: !3, line: 1, type: !10)
> +!16 = !DIExpression(DW_OP_plus, 8, DW_OP_plus, 8)
> +!17 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "d", arg: 4,
> scope: !6, file: !3, line: 1, type: !9)
> +!18 = !DIExpression(DW_OP_plus, 16, DW_OP_plus, 8, DW_OP_deref)
> +!19 = !DILocation(line: 1, scope: !6)
>
>
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