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e52f04f5e6
Don't terminate location ranges for register-described variables at the end of machine basic block if this register is never modified in the function body, except for the prologue and epilogue. Prologue location is guessed by FrameSetup flags on MachineInstructions, while epilogue location is deduced from debug locations of instructions in the basic blocks ending with return instructions. This patch is mostly targeted to fix non-trivial debug locations for variables addressed via stack and frame pointers. It is not really a generic fix. We can still produce poor debug info for register-described variables if this register *is* modified somewhere in the function, but in unrelated places. This might be the case for the debug info in optimized binaries (e.g. for local variables in inlined functions). LiveDebugVariables pass in CodeGen attempts to fix this problem by adjusting DBG_VALUE instructions, but this pass is tied to greedy register allocator, which is used in optimized builds only. Proper fix would likely involve generalizing LiveDebugVariables to all register allocators. See more discussion in http://reviews.llvm.org/D3933 review thread. I'm proceeding with this patch to fix immediate severe problems and important cases, e.g. fix completely broken debug info with AddressSanitizer and fix PR19307 (missing debug info for by-value std::string arguments). llvm-svn: 210492
71 lines
3.9 KiB
LLVM
71 lines
3.9 KiB
LLVM
; A by-value struct is a register-indirect value (breg).
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; RUN: llc %s -filetype=asm -o - | FileCheck %s
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; CHECK: DW_AT_location
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; CHECK-NEXT: .byte 112
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; 112 = 0x70 = DW_OP_breg0
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; rdar://problem/13658587
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;
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; Generated from
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;
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; struct five
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; {
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; int a;
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; int b;
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; int c;
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; int d;
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; int e;
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; };
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;
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; int
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; return_five_int (struct five f)
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; {
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; return f.a;
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; }
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n32:64-S128"
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target triple = "arm64-apple-ios3.0.0"
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%struct.five = type { i32, i32, i32, i32, i32 }
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; Function Attrs: nounwind ssp
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define i32 @return_five_int(%struct.five* %f) #0 {
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entry:
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call void @llvm.dbg.declare(metadata !{%struct.five* %f}, metadata !17), !dbg !18
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%a = getelementptr inbounds %struct.five* %f, i32 0, i32 0, !dbg !19
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%0 = load i32* %a, align 4, !dbg !19
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ret i32 %0, !dbg !19
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}
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; Function Attrs: nounwind readnone
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declare void @llvm.dbg.declare(metadata, metadata) #1
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attributes #0 = { nounwind ssp }
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attributes #1 = { nounwind readnone }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!16, !20}
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!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"LLVM version 3.4 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [struct_by_value.c] [DW_LANG_C99]
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!1 = metadata !{metadata !"struct_by_value.c", metadata !""}
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!2 = metadata !{}
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!3 = metadata !{metadata !4}
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!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"return_five_int", metadata !"return_five_int", metadata !"", i32 13, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (%struct.five*)* @return_five_int, null, null, metadata !2, i32 14} ; [ DW_TAG_subprogram ] [line 13] [def] [scope 14] [return_five_int]
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!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [struct_by_value.c]
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!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
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!7 = metadata !{metadata !8, metadata !9}
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!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
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!9 = metadata !{i32 786451, metadata !1, null, metadata !"five", i32 1, i64 160, i64 32, i32 0, i32 0, null, metadata !10, i32 0, null, null, null} ; [ DW_TAG_structure_type ] [five] [line 1, size 160, align 32, offset 0] [def] [from ]
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!10 = metadata !{metadata !11, metadata !12, metadata !13, metadata !14, metadata !15}
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!11 = metadata !{i32 786445, metadata !1, metadata !9, metadata !"a", i32 3, i64 32, i64 32, i64 0, i32 0, metadata !8} ; [ DW_TAG_member ] [a] [line 3, size 32, align 32, offset 0] [from int]
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!12 = metadata !{i32 786445, metadata !1, metadata !9, metadata !"b", i32 4, i64 32, i64 32, i64 32, i32 0, metadata !8} ; [ DW_TAG_member ] [b] [line 4, size 32, align 32, offset 32] [from int]
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!13 = metadata !{i32 786445, metadata !1, metadata !9, metadata !"c", i32 5, i64 32, i64 32, i64 64, i32 0, metadata !8} ; [ DW_TAG_member ] [c] [line 5, size 32, align 32, offset 64] [from int]
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!14 = metadata !{i32 786445, metadata !1, metadata !9, metadata !"d", i32 6, i64 32, i64 32, i64 96, i32 0, metadata !8} ; [ DW_TAG_member ] [d] [line 6, size 32, align 32, offset 96] [from int]
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!15 = metadata !{i32 786445, metadata !1, metadata !9, metadata !"e", i32 7, i64 32, i64 32, i64 128, i32 0, metadata !8} ; [ DW_TAG_member ] [e] [line 7, size 32, align 32, offset 128] [from int]
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!16 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
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!17 = metadata !{i32 786689, metadata !4, metadata !"f", metadata !5, i32 16777229, metadata !9, i32 8192, i32 0} ; [ DW_TAG_arg_variable ] [f] [line 13]
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!18 = metadata !{i32 13, i32 0, metadata !4, null}
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!19 = metadata !{i32 16, i32 0, metadata !4, null}
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!20 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
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