From bcae242878f2381f40b05144e72cc4ee8f817ff6 Mon Sep 17 00:00:00 2001 From: Markus Lavin Date: Fri, 12 Apr 2019 08:23:55 +0000 Subject: [PATCH] [DebugInfo] DW_OP_deref_size in PrologEpilogInserter. The PrologEpilogInserter need to insert a DW_OP_deref_size before prepending a memory location expression to an already implicit expression to avoid having the existing expression act on the memory address instead of the value behind it. The reason for using DW_OP_deref_size and not plain DW_OP_deref is that big-endian targets need to read the right size as simply truncating a larger read would yield the wrong result (LSB bytes are not at the lower address). Differential Revision: https://reviews.llvm.org/D59687 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358268 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/IR/DebugInfoMetadata.h | 3 + lib/CodeGen/AsmPrinter/DwarfExpression.cpp | 4 ++ lib/CodeGen/MIRParser/MIParser.cpp | 5 ++ lib/CodeGen/PrologEpilogInserter.cpp | 16 +++++- lib/IR/DebugInfoMetadata.cpp | 15 +++++ test/CodeGen/X86/prologepilog_deref_size.mir | 59 ++++++++++++++++++++ 6 files changed, 99 insertions(+), 3 deletions(-) create mode 100644 test/CodeGen/X86/prologepilog_deref_size.mir diff --git a/include/llvm/IR/DebugInfoMetadata.h b/include/llvm/IR/DebugInfoMetadata.h index 2ec8de14d66..357074a3649 100644 --- a/include/llvm/IR/DebugInfoMetadata.h +++ b/include/llvm/IR/DebugInfoMetadata.h @@ -2510,6 +2510,9 @@ public: /// Return whether this is a piece of an aggregate variable. bool isFragment() const { return getFragmentInfo().hasValue(); } + /// Return whether this is an implicit location description. + bool isImplicit() const; + /// Append \p Ops with operations to apply the \p Offset. static void appendOffset(SmallVectorImpl &Ops, int64_t Offset); diff --git a/lib/CodeGen/AsmPrinter/DwarfExpression.cpp b/lib/CodeGen/AsmPrinter/DwarfExpression.cpp index 41fa45f2507..48f8addd031 100644 --- a/lib/CodeGen/AsmPrinter/DwarfExpression.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfExpression.cpp @@ -434,6 +434,10 @@ void DwarfExpression::addExpression(DIExpressionCursor &&ExprCursor, assert(LocationKind != Register); emitOp(dwarf::DW_OP_xderef); break; + case dwarf::DW_OP_deref_size: + emitOp(dwarf::DW_OP_deref_size); + emitUnsigned(Op->getArg(0)); + break; default: llvm_unreachable("unhandled opcode found in expression"); } diff --git a/lib/CodeGen/MIRParser/MIParser.cpp b/lib/CodeGen/MIRParser/MIParser.cpp index 971944be2f9..d414b6a0b4b 100644 --- a/lib/CodeGen/MIRParser/MIParser.cpp +++ b/lib/CodeGen/MIRParser/MIParser.cpp @@ -1854,6 +1854,11 @@ bool MIParser::parseDIExpression(MDNode *&Expr) { Elements.push_back(Op); continue; } + if (unsigned Enc = dwarf::getAttributeEncoding(Token.stringValue())) { + lex(); + Elements.push_back(Enc); + continue; + } return error(Twine("invalid DWARF op '") + Token.stringValue() + "'"); } diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp index 67834c8c352..31f962eba42 100644 --- a/lib/CodeGen/PrologEpilogInserter.cpp +++ b/lib/CodeGen/PrologEpilogInserter.cpp @@ -1172,12 +1172,22 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &MF, assert(i == 0 && "Frame indices can only appear as the first " "operand of a DBG_VALUE machine instruction"); unsigned Reg; + unsigned FrameIdx = MI.getOperand(0).getIndex(); + unsigned Size = MF.getFrameInfo().getObjectSize(FrameIdx); + int64_t Offset = - TFI->getFrameIndexReference(MF, MI.getOperand(0).getIndex(), Reg); + TFI->getFrameIndexReference(MF, FrameIdx, Reg); MI.getOperand(0).ChangeToRegister(Reg, false /*isDef*/); MI.getOperand(0).setIsDebug(); - auto *DIExpr = DIExpression::prepend(MI.getDebugExpression(), - DIExpression::NoDeref, Offset); + + const DIExpression *DIExpr = MI.getDebugExpression(); + // If we already have a Implicit location expression we need to insert + // a deref before prepending a Memory location expression. + if (DIExpr->isImplicit()) { + SmallVector Ops = {dwarf::DW_OP_deref_size, Size}; + DIExpr = DIExpression::prependOpcodes(DIExpr, Ops, DIExpression::WithStackValue); + } + DIExpr = DIExpression::prepend(DIExpr, DIExpression::NoDeref, Offset); MI.getOperand(3).setMetadata(DIExpr); continue; } diff --git a/lib/IR/DebugInfoMetadata.cpp b/lib/IR/DebugInfoMetadata.cpp index 7158e5764fa..4ef38b6f7fe 100644 --- a/lib/IR/DebugInfoMetadata.cpp +++ b/lib/IR/DebugInfoMetadata.cpp @@ -833,6 +833,7 @@ unsigned DIExpression::ExprOperand::getSize() const { case dwarf::DW_OP_LLVM_fragment: return 3; case dwarf::DW_OP_constu: + case dwarf::DW_OP_deref_size: case dwarf::DW_OP_plus_uconst: return 2; default: @@ -889,6 +890,7 @@ bool DIExpression::isValid() const { case dwarf::DW_OP_shr: case dwarf::DW_OP_shra: case dwarf::DW_OP_deref: + case dwarf::DW_OP_deref_size: case dwarf::DW_OP_xderef: case dwarf::DW_OP_lit0: case dwarf::DW_OP_not: @@ -899,6 +901,19 @@ bool DIExpression::isValid() const { return true; } +bool DIExpression::isImplicit() const { + unsigned N = getNumElements(); + if (isValid() && N > 0) { + switch (getElement(N-1)) { + case dwarf::DW_OP_stack_value: return true; + case dwarf::DW_OP_LLVM_fragment: + return N > 1 && getElement(N-2) == dwarf::DW_OP_stack_value; + default: break; + } + } + return false; +} + Optional DIExpression::getFragmentInfo(expr_op_iterator Start, expr_op_iterator End) { for (auto I = Start; I != End; ++I) diff --git a/test/CodeGen/X86/prologepilog_deref_size.mir b/test/CodeGen/X86/prologepilog_deref_size.mir new file mode 100644 index 00000000000..0b0ea5d881e --- /dev/null +++ b/test/CodeGen/X86/prologepilog_deref_size.mir @@ -0,0 +1,59 @@ +# RUN: llc -run-pass=prologepilog -o - %s | FileCheck %s +--- | + ; ModuleID = 'dbg.opt.ll' + source_filename = "dbg.c" + target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + target triple = "x86_64-unknown-linux-gnu" + + ; Function Attrs: noinline nounwind uwtable + define dso_local zeroext i16 @foo(i16 zeroext %d0, i16 zeroext %d1, i16 zeroext %d2, i16 zeroext %d3, i16 zeroext %d4, i16 zeroext %d5, i16 zeroext %d6, i16 zeroext %d7, i16 zeroext %d8, i16 signext %x) #0 !dbg !7 { + entry: + call void @llvm.dbg.value(metadata i16 %x, metadata !32, metadata !DIExpression(DW_OP_LLVM_convert, 16, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value)), !dbg !34 + ret i16 %x + } + + ; Function Attrs: nounwind readnone speculatable + declare void @llvm.dbg.value(metadata, metadata, metadata) #1 + + attributes #0 = { noinline nounwind uwtable } + attributes #1 = { nounwind readnone speculatable } + + !llvm.dbg.cu = !{!0} + !llvm.module.flags = !{!3, !4, !5} + !llvm.ident = !{!6} + + !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 9.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None) + !1 = !DIFile(filename: "dbg.c", directory: "/tmp") + !2 = !{} + !3 = !{i32 2, !"Dwarf Version", i32 4} + !4 = !{i32 2, !"Debug Info Version", i32 3} + !5 = !{i32 1, !"wchar_size", i32 4} + !6 = !{!"clang version 9.0.0"} + !7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2) + !8 = !DISubroutineType(types: !9) + !9 = !{!10, !10, !10, !10, !10, !10, !10, !10, !10, !10, !10} + !10 = !DIDerivedType(tag: DW_TAG_typedef, name: "T", file: !1, line: 1, baseType: !11) + !11 = !DIBasicType(name: "signed short", size: 16, encoding: DW_ATE_signed) + !32 = !DILocalVariable(name: "y", scope: !7, file: !1, line: 3, type: !33) + !33 = !DIBasicType(name: "signed int", size: 32, encoding: DW_ATE_signed) + !34 = !DILocation(line: 3, column: 20, scope: !7) + +... +--- +name: foo +tracksRegLiveness: true +fixedStack: + - { id: 0, type: default, offset: 24, size: 2, alignment: 8, stack-id: 0, + isImmutable: true, isAliased: false, callee-saved-register: '', callee-saved-restored: true, + debug-info-variable: '', debug-info-expression: '', debug-info-location: '' } +stack: [] +constants: [] +machineFunctionInfo: {} +body: | + bb.0.entry: + renamable $ax = MOV16rm %fixed-stack.0, 1, $noreg, 0, $noreg :: (load 2 from %fixed-stack.0, align 8) + DBG_VALUE %fixed-stack.0, 0, !32, !DIExpression(DW_OP_LLVM_convert, 16, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), debug-location !34 + RET 0, $ax +... +# CHECK: machineFunctionInfo +# CHECK: DIExpression(DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref_size, 2, DW_OP_LLVM_convert, 16, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value) -- 2.50.1