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48bac26038
LowerDbgDeclare inserts a dbg.value before each use of an address described by a dbg.declare. When inserting a dbg.value before a CallInst use, however, it fails to append DW_OP_deref to the DIExpression. The DW_OP_deref is needed to reflect the fact that a dbg.value describes a source variable directly (as opposed to a dbg.declare, which relies on pointer indirection). This patch adds in the DW_OP_deref where needed. This results in the correct values being shown during a debug session for a program compiled with ASan and optimizations (see https://reviews.llvm.org/D49520). Note that ConvertDebugDeclareToDebugValue is already correct -- no changes there were needed. One complication is that SelectionDAG is unable to distinguish between direct and indirect frame-index (FRAMEIX) SDDbgValues. This patch also fixes this long-standing issue in order to not regress integration tests relying on the incorrect assumption that all frame-index SDDbgValues are indirect. This is a necessary fix: the newly-added DW_OP_derefs cannot be lowered properly otherwise. Basically the fix prevents a direct SDDbgValue with DIExpression(DW_OP_deref) from being dereferenced twice by a debugger. There were a handful of tests relying on this incorrect "FRAMEIX => indirect" assumption which actually had incorrect DW_AT_locations: these are all fixed up in this patch. Testing: - check-llvm, and an end-to-end test using lldb to debug an optimized program. - Existing unit tests for DIExpression::appendToStack fully cover the new DIExpression::append utility. - check-debuginfo (the debug info integration tests) Differential Revision: https://reviews.llvm.org/D49454 llvm-svn: 338069
67 lines
2.5 KiB
LLVM
67 lines
2.5 KiB
LLVM
; RUN: llc -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
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;
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; Generated at -Os from:
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; void *foo(void *dst);
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; void start() {
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; unsigned size;
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; foo(&size);
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; if (size != 0) { // Work around a bug to preserve the dbg.value.
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; }
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; }
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; ModuleID = 'test1.cpp'
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target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
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target triple = "arm64-apple-ios"
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; Function Attrs: nounwind optsize
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define void @_Z5startv() #0 !dbg !4 {
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entry:
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%size = alloca i32, align 4
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%0 = bitcast i32* %size to i8*, !dbg !15
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%call = call i8* @_Z3fooPv(i8* %0) #3, !dbg !15
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call void @llvm.dbg.value(metadata i32* %size, metadata !10, metadata !16), !dbg !17
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; The *location* of the variable should be $sp+12. This tells the debugger to
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; look up its value in [$sp+12].
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; CHECK: .debug_info contents:
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; CHECK: DW_TAG_variable
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; CHECK-NEXT: DW_AT_location
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; CHECK-NEXT: DW_OP_breg31 WSP+12
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; CHECK-NEXT: DW_AT_name {{.*}}"size"
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ret void, !dbg !18
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}
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; Function Attrs: optsize
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declare i8* @_Z3fooPv(i8*) #1
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; Function Attrs: nounwind readnone
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declare void @llvm.dbg.value(metadata, metadata, metadata) #2
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attributes #0 = { nounwind optsize }
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attributes #1 = { optsize }
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attributes #2 = { nounwind readnone }
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attributes #3 = { nounwind optsize }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!12, !13}
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!llvm.ident = !{!14}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.6.0 (trunk 223149) (llvm/trunk 223115)", isOptimized: true, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
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!1 = !DIFile(filename: "<stdin>", directory: "")
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!2 = !{}
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!4 = distinct !DISubprogram(name: "start", linkageName: "_Z5startv", line: 2, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 3, file: !5, scope: !6, type: !7, retainedNodes: !9)
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!5 = !DIFile(filename: "test1.c", directory: "")
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!6 = !DIFile(filename: "test1.c", directory: "")
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!7 = !DISubroutineType(types: !8)
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!8 = !{null}
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!9 = !{!10}
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!10 = !DILocalVariable(name: "size", line: 4, scope: !4, file: !6, type: !11)
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!11 = !DIBasicType(tag: DW_TAG_base_type, name: "unsigned int", size: 32, align: 32, encoding: DW_ATE_unsigned)
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!12 = !{i32 2, !"Dwarf Version", i32 2}
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!13 = !{i32 2, !"Debug Info Version", i32 3}
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!14 = !{!"clang version 3.6.0 (trunk 223149) (llvm/trunk 223115)"}
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!15 = !DILocation(line: 5, column: 3, scope: !4)
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!16 = !DIExpression(DW_OP_deref)
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!17 = !DILocation(line: 4, column: 12, scope: !4)
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!18 = !DILocation(line: 8, column: 1, scope: !4)
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