Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp =================================================================== --- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -5474,7 +5474,6 @@ MachineFunction &MF = DAG.getMachineFunction(); const TargetInstrInfo *TII = DAG.getSubtarget().getInstrInfo(); - bool IsIndirect = false; Optional Op; // Some arguments' frame index is recorded during argument lowering. int FI = FuncInfo.getArgumentFrameIndex(Arg); @@ -5496,7 +5495,6 @@ } if (Reg) { Op = MachineOperand::CreateReg(Reg, false); - IsIndirect = IsDbgDeclare; } } @@ -5540,7 +5538,6 @@ } Op = MachineOperand::CreateReg(VMI->second, false); - IsIndirect = IsDbgDeclare; } else if (ArgRegsAndSizes.size() > 1) { // This was split due to the calling convention, and no virtual register // mapping exists for the value. @@ -5554,9 +5551,26 @@ assert(Variable->isValidLocationForIntrinsic(DL) && "Expected inlined-at fields to agree"); - IsIndirect = (Op->isReg()) ? IsIndirect : true; - if (IsIndirect) + + // If the argument arrives in a stack slot, then what the IR thought was a + // normal Value is actually in memory, and we must add a deref to load it. + if (Op->isFI()) { + int FI = Op->getIndex(); + unsigned Size = DAG.getMachineFunction().getFrameInfo().getObjectSize(FI); + if (Expr->isImplicit()) { + SmallVector Ops = {dwarf::DW_OP_deref_size, Size}; + Expr = DIExpression::prependOpcodes(Expr, Ops); + } else { + Expr = DIExpression::prepend(Expr, DIExpression::DerefBefore); + } + } + + // If this location was specified with a dbg.declare, then it and its + // expression calculate the address of the variable. Append a deref to + // force it to be a memory location. + if (IsDbgDeclare) Expr = DIExpression::append(Expr, {dwarf::DW_OP_deref}); + FuncInfo.ArgDbgValues.push_back( BuildMI(MF, DL, TII->get(TargetOpcode::DBG_VALUE), false, *Op, Variable, Expr)); Index: test/DebugInfo/X86/stack-arg-deref.ll =================================================================== --- /dev/null +++ test/DebugInfo/X86/stack-arg-deref.ll @@ -0,0 +1,85 @@ +; RUN: llc -stop-before=finalize-isel -o - %s -mtriple=i386-- | FileCheck %s --check-prefix=MIR +; RUN: llc -o - %s -mtriple=i386-- --filetype=obj | llvm-dwarfdump - | FileCheck %s --check-prefix=DWARF --implicit-check-not=DW_TAG_subprogram +; REQUIRES: object-emission +; +; Test that, when arguments are passed on the stack (such as i386), +; variable location dereferences occur in the right place. When referring to +; argument stack slots a deref must be used to load the slot first. + +; MIR: ![[FOOVAR:[0-9]+]] = !DILocalVariable(name: "foovar" +; MIR: ![[BARVAR:[0-9]+]] = !DILocalVariable(name: "barvar" +; MIR: ![[BAZVAR:[0-9]+]] = !DILocalVariable(name: "bazvar" + +; Plain i32 on the stack. +; MIR-LABEL: name: foo +; MIR: DBG_VALUE %fixed-stack.0, $noreg, ![[FOOVAR]], +; MIR-SAME: !DIExpression(DW_OP_deref) +; DWARF: DW_TAG_subprogram +; DWARF-LABEL: DW_AT_name ("cheese") +; DWARF: DW_TAG_variable +; DWARF-NEXT: DW_AT_location (DW_OP_fbreg +4) +; DWARF-NEXT: DW_AT_name ("foovar") +define i8 @foo(i32 %blah) !dbg !20 { +entry: + call void @llvm.dbg.value(metadata i32 %blah, metadata !23, metadata !DIExpression()), !dbg !21 + ret i8 0, !dbg !21 +} + +; Pointer on the stack that we fiddle with. +; MIR-LABEL: name: bar +; MIR: DBG_VALUE %fixed-stack.0, $noreg, ![[BARVAR]], +; MIR-SAME: !DIExpression(DW_OP_deref_size, 4, DW_OP_plus_uconst, 4, DW_OP_stack_value) +; DWARF: DW_TAG_subprogram +; DWARF-LABEL: DW_AT_name ("nope") +; DWARF: DW_TAG_variable +; DWARF-NEXT: DW_AT_location (DW_OP_fbreg +4, DW_OP_deref_size 0x4, DW_OP_plus_uconst 0x4, DW_OP_stack_value) +; DWARF-NEXT: DW_AT_name ("barvar") +define i8 @bar(i32 *%blah) !dbg !30 { +entry: + call void @llvm.dbg.value(metadata i32* %blah, metadata !33, metadata !DIExpression(DW_OP_plus_uconst, 4, DW_OP_stack_value)), !dbg !31 + ret i8 0, !dbg !31 +} + +; Pointer that we use as a dbg.declare variable location, after fiddling with +; the pointer value. +; MIR-LABEL: name: baz +; MIR: DBG_VALUE %fixed-stack.0, $noreg, ![[BAZVAR]], +; MIR-SAME: !DIExpression(DW_OP_deref, DW_OP_plus_uconst, 4, DW_OP_deref) +; DWARF: DW_TAG_subprogram +; DWARF-LABEL: DW_AT_name ("brains") +; DWARF: DW_TAG_variable +; DWARF-NEXT: DW_AT_location (DW_OP_fbreg +4, DW_OP_deref, DW_OP_plus_uconst 0x4) +; DWARF-NEXT: DW_AT_name ("bazvar") +define i8 @baz(i32 *%blah) !dbg !40 { +entry: + call void @llvm.dbg.declare(metadata i32* %blah, metadata !43, metadata !DIExpression(DW_OP_plus_uconst, 4)), !dbg !41 + ret i8 0, !dbg !41 +} + +declare void @llvm.dbg.value(metadata, metadata, metadata) +declare void @llvm.dbg.declare(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!5} + +!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "asdf", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2) +!1 = !DIFile(filename: "nil", directory: "/") +!2 = !{} +!5 = !{i32 2, !"Debug Info Version", i32 3} +!7 = !DISubroutineType(types: !2) +!8 = !DIBasicType(name: "i32", size: 32, encoding: DW_ATE_signed) + +!20 = distinct !DISubprogram(name: "cheese", linkageName: "cheese", scope: null, file: !1, line: 12, type: !7, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, retainedNodes: !22) +!21 = !DILocation(line: 1, column: 1, scope: !20) +!22 = !{!23} +!23 = !DILocalVariable(name: "foovar", scope: !20, file: !1, line: 14, type: !8) + +!30 = distinct !DISubprogram(name: "nope", linkageName: "nope", scope: null, file: !1, line: 12, type: !7, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, retainedNodes: !32) +!31 = !DILocation(line: 1, column: 1, scope: !30) +!32 = !{!33} +!33 = !DILocalVariable(name: "barvar", scope: !30, file: !1, line: 14, type: !8) + +!40 = distinct !DISubprogram(name: "brains", linkageName: "brains", scope: null, file: !1, line: 12, type: !7, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !0, retainedNodes: !42) +!41 = !DILocation(line: 1, column: 1, scope: !40) +!42 = !{!43} +!43 = !DILocalVariable(name: "bazvar", scope: !40, file: !1, line: 14, type: !8)