maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/DebugInfo/MIR/X86/bit-piece-dh.mir

98 lines
3.5 KiB
Plaintext
Raw Normal View History

llvm-dwarfdump: Replace -debug-dump=sect option with individual options. As discussed on llvm-dev in http://lists.llvm.org/pipermail/llvm-dev/2017-September/117301.html this changes the command line interface of llvm-dwarfdump to match the one used by the dwarfdump utility shipping on macOS. In addition to being shorter to type this format also has the advantage of allowing more than one section to be specified at the same time. In a nutshell, with this change $ llvm-dwarfdump --debug-dump=info $ llvm-dwarfdump --debug-dump=apple-objc becomes $ dwarfdump --debug-info --apple-objc Differential Revision: https://reviews.llvm.org/D37714 llvm-svn: 312970
2017-09-12 06:59:45 +08:00
# RUN: llc -filetype=obj -o - %s | llvm-dwarfdump --debug-info - | FileCheck %s
Fix LLVM's use of DW_OP_bit_piece in DWARF expressions. LLVM's use of DW_OP_bit_piece is incorrect and a based on a misunderstanding of the wording in the DWARF specification. The offset argument of DW_OP_bit_piece refers to the offset into the location that is on the top of the DWARF expression stack, and not an offset into the source variable. This has since also been clarified in the DWARF specification. This patch fixes all uses of DW_OP_bit_piece to emit the correct offset and simplifies the DwarfExpression class to semi-automaticaly emit empty DW_OP_pieces to adjust the offset of the source variable, thus simplifying the code using DwarfExpression. While this is an incompatible bugfix, in practice I don't expect this to be much of a problem since LLVM's old interpretation and the correct interpretation of DW_OP_bit_piece differ only when there are gaps in the fragmented locations of the described variables or if individual fragments are smaller than a byte. LLDB at least won't interpret locations with gaps in them because is has no way to present undefined bits in a variable, and there is a high probability that an old-form expression will be malformed when interpreted correctly, because the DW_OP_bit_piece offset will be outside of the location at the top of the stack. As a nice side-effect, this patch enables us to use a more efficient encoding for subregisters: In order to express a sub-register at a non-zero offset we now use a DW_OP_bit_piece instead of shifting the value into place manually. This patch also adds missing test coverage for code paths that weren't exercised before. <rdar://problem/29335809> Differential Revision: https://reviews.llvm.org/D27550 llvm-svn: 289266
2016-12-10 04:43:40 +08:00
# CHECK: .debug_info contents:
# CHECK: DW_TAG_variable
[dwarfdump] Pretty print location expressions and location lists Summary: Based on Fred's patch here: https://reviews.llvm.org/D6771 I can't seem to commandeer the old review, so I'm creating a new one. With that change the locations exrpessions are pretty printed inline in the DIE tree. The output looks like this for debug_loc entries: DW_AT_location [DW_FORM_data4] (0x00000000 0x0000000000000001 - 0x000000000000000b: DW_OP_consts +3 0x000000000000000b - 0x0000000000000012: DW_OP_consts +7 0x0000000000000012 - 0x000000000000001b: DW_OP_reg0 RAX, DW_OP_piece 0x4 0x000000000000001b - 0x0000000000000024: DW_OP_breg5 RDI+0) And like this for debug_loc.dwo entries: DW_AT_location [DW_FORM_sec_offset] (0x00000000 Addr idx 2 (w/ length 190): DW_OP_consts +0, DW_OP_stack_value Addr idx 3 (w/ length 23): DW_OP_reg0 RAX, DW_OP_piece 0x4) Simple locations without ranges are printed inline: DW_AT_location [DW_FORM_block1] (DW_OP_reg4 RSI, DW_OP_piece 0x4, DW_OP_bit_piece 0x20 0x0) The debug_loc(.dwo) dumping in changed accordingly to factor the code. Reviewers: dblaikie, aprantl, friss Subscribers: mgorny, javed.absar, hiraditya, llvm-commits, JDevlieghere Differential Revision: https://reviews.llvm.org/D37123 llvm-svn: 312042
2017-08-30 05:41:21 +08:00
# CHECK-NEXT: DW_AT_location {{.*}} (DW_OP_reg1 RDX, DW_OP_bit_piece 0x8 0x8)
Improve the accuracy of variable ranges .debug_loc location lists. For the following motivating example bool c(); void f(); bool start() { bool result = c(); if (!c()) { result = false; goto exit; } f(); result = true; exit: return result; } we would previously generate a single DW_AT_const_value(1) because only the DBG_VALUE in the second-to-last basic block survived codegen. This patch improves the heuristic used to determine when a DBG_VALUE is available at the beginning of its variable's enclosing lexical scope: - Stop giving singular constants blanket permission to take over the entire scope. There is still a special case for constants in the function prologue that we also miight want to retire later. - Use the lexical scope information to determine available-at-entry instead of proximity to the function prologue. After this patch we generate a location list with a more accurate narrower availability for the constant true value. As a pleasant side effect, we also generate inline locations instead of location lists where a loacation covers the entire range of the enclosing lexical scope. Measured on compiling llc with four targets this doesn't have an effect on compile time and reduces the size of the debug info for llc by ~600K. rdar://problem/30286912 llvm-svn: 305599
2017-06-17 06:40:04 +08:00
# CHECK-NEXT: DW_AT_name {{.*}}"dh"
Fix LLVM's use of DW_OP_bit_piece in DWARF expressions. LLVM's use of DW_OP_bit_piece is incorrect and a based on a misunderstanding of the wording in the DWARF specification. The offset argument of DW_OP_bit_piece refers to the offset into the location that is on the top of the DWARF expression stack, and not an offset into the source variable. This has since also been clarified in the DWARF specification. This patch fixes all uses of DW_OP_bit_piece to emit the correct offset and simplifies the DwarfExpression class to semi-automaticaly emit empty DW_OP_pieces to adjust the offset of the source variable, thus simplifying the code using DwarfExpression. While this is an incompatible bugfix, in practice I don't expect this to be much of a problem since LLVM's old interpretation and the correct interpretation of DW_OP_bit_piece differ only when there are gaps in the fragmented locations of the described variables or if individual fragments are smaller than a byte. LLDB at least won't interpret locations with gaps in them because is has no way to present undefined bits in a variable, and there is a high probability that an old-form expression will be malformed when interpreted correctly, because the DW_OP_bit_piece offset will be outside of the location at the top of the stack. As a nice side-effect, this patch enables us to use a more efficient encoding for subregisters: In order to express a sub-register at a non-zero offset we now use a DW_OP_bit_piece instead of shifting the value into place manually. This patch also adds missing test coverage for code paths that weren't exercised before. <rdar://problem/29335809> Differential Revision: https://reviews.llvm.org/D27550 llvm-svn: 289266
2016-12-10 04:43:40 +08:00
--- |
; Manually created after:
; char f(int i) {
; char dh = i>>8;
; return dh;
; }
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"
define signext i8 @f(i32 %i) local_unnamed_addr #0 !dbg !7 {
entry:
tail call void @llvm.dbg.value(metadata i32 %i, i64 0, metadata !13, metadata !15), !dbg !16
%shr1 = lshr i32 %i, 8, !dbg !17
%conv = trunc i32 %shr1 to i8, !dbg !18
tail call void @llvm.dbg.value(metadata i8 %conv, i64 0, metadata !14, metadata !15), !dbg !19
ret i8 %conv, !dbg !20
}
declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #0
attributes #0 = { nounwind readnone }
!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 4.0.0 (trunk 288677) (llvm/trunk 288679)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "t.c", directory: "/")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"PIC Level", i32 2}
!6 = !{!"clang version 4.0.0 (trunk 288677) (llvm/trunk 288679)"}
!7 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
!8 = !DISubroutineType(types: !9)
!9 = !{!10, !11}
!10 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !{!13, !14}
!13 = !DILocalVariable(name: "i", arg: 1, scope: !7, file: !1, line: 1, type: !11)
!14 = !DILocalVariable(name: "dh", scope: !7, file: !1, line: 2, type: !10)
!15 = !DIExpression()
!16 = !DILocation(line: 1, column: 12, scope: !7)
!17 = !DILocation(line: 2, column: 14, scope: !7)
!18 = !DILocation(line: 2, column: 13, scope: !7)
!19 = !DILocation(line: 2, column: 8, scope: !7)
!20 = !DILocation(line: 3, column: 3, scope: !7)
...
---
name: f
alignment: 4
exposesReturnsTwice: false
legalized: false
regBankSelected: false
selected: false
tracksRegLiveness: true
liveins:
- { reg: '%edi' }
frameInfo:
isFrameAddressTaken: false
isReturnAddressTaken: false
hasStackMap: false
hasPatchPoint: false
stackSize: 8
offsetAdjustment: 0
maxAlignment: 0
adjustsStack: false
hasCalls: false
maxCallFrameSize: 0
hasOpaqueSPAdjustment: false
hasVAStart: false
hasMustTailInVarArgFunc: false
fixedStack:
- { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16 }
body: |
bb.0.entry:
liveins: %edi, %rbp
frame-setup PUSH64r killed %rbp, implicit-def %rsp, implicit %rsp
CFI_INSTRUCTION def_cfa_offset 16
CFI_INSTRUCTION offset %rbp, -16
%rbp = frame-setup MOV64rr %rsp
CFI_INSTRUCTION def_cfa_register %rbp
DBG_VALUE debug-use %dh, debug-use _, !14, !15, debug-location !16
%edi = SHR32ri killed %edi, 8, implicit-def dead %eflags, debug-location !17
%eax = MOVSX32rr8 %dil, implicit killed %edi, debug-location !20
%rbp = POP64r implicit-def %rsp, implicit %rsp, debug-location !20
RETQ %eax, debug-location !20
...