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/X86/dw_op_minus_direct.ll

59 lines
2.4 KiB
LLVM
Raw Normal View History

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
; Test dwarf codegen of DW_OP_minus.
llvm-dwarfdump: Make -brief the default and add a -verbose option instead. Differential Revision: https://reviews.llvm.org/D37717 llvm-svn: 312972
2017-09-12 07:05:20 +08:00
; RUN: llc -filetype=obj < %s | llvm-dwarfdump -v - | FileCheck %s
; RUN: llc -dwarf-version=2 -filetype=obj < %s | llvm-dwarfdump -v - \
Don't emit locations that need a DW_OP_stack_value in DWARF 2 & 3. https://bugs.llvm.org/show_bug.cgi?id=32382 llvm-svn: 300883
2017-04-21 04:42:33 +08:00
; RUN: | FileCheck %s --check-prefix=DWARF2
llvm-dwarfdump: Make -brief the default and add a -verbose option instead. Differential Revision: https://reviews.llvm.org/D37717 llvm-svn: 312972
2017-09-12 07:05:20 +08:00
; RUN: llc -dwarf-version=3 -filetype=obj < %s | llvm-dwarfdump -v - \
Don't emit locations that need a DW_OP_stack_value in DWARF 2 & 3. https://bugs.llvm.org/show_bug.cgi?id=32382 llvm-svn: 300883
2017-04-21 04:42:33 +08:00
; RUN: | FileCheck %s --check-prefix=DWARF2
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
; This was derived manually from:
; int inc(int i) {
; return i+1;
; }
Don't emit locations that need a DW_OP_stack_value in DWARF 2 & 3. https://bugs.llvm.org/show_bug.cgi?id=32382 llvm-svn: 300883
2017-04-21 04:42:33 +08:00
; DWARF2: .debug_info
; DWARF2: DW_TAG_formal_parameter
; DWARF2-NEXT: DW_AT_name {{.*}}"i"
[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
; DWARF2-NOT: DW_AT_location
Don't emit locations that need a DW_OP_stack_value in DWARF 2 & 3. https://bugs.llvm.org/show_bug.cgi?id=32382 llvm-svn: 300883
2017-04-21 04:42:33 +08:00
[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: .debug_loc contents:
; CHECK: 0x00000000:
[DebugInfo] Stop changing labels for register-described parameter DBG_VALUEs Summary: This is a follow-up to D57510. This patch stops DebugHandlerBase from changing the starting label for the first non-overlapping, register-described parameter DBG_VALUEs to the beginning of the function. That code did not consider what defined the registers, which could result in the ranges for the debug values starting before their defining instructions. We currently do not emit debug values for constant values directly at the start of the function, so this code is still useful for such values, but my intention is to remove the code from DebugHandlerBase completely when we get there. One reason for removing it is that the code violates the history map's ranges, which I think can make it quite confusing when troubleshooting. In D57510, PrologEpilogInserter was amended so that parameter DBG_VALUEs now are kept at the start of the entry block, even after emission of prologue code. That was done to reduce the degradation of debug completeness from this patch. PR40638 is another example, where the lexical-scope trimming that LDV does, in combination with scheduling, results in instructions after the prologue being left without locations. There might be other cases where the DBG_VALUEs are pushed further down, for which the DebugHandlerBase code may be helpful, but as it now quite often result in incorrect locations, even after the prologue, it seems better to remove that code, and try to work our way up with accurate locations. In the long run we should maybe not aim to provide accurate locations inside the prologue. Some single location descriptions, at least those referring to stack values, generate inaccurate values inside the epilogue, so we maybe should not aim to achieve accuracy for location lists. However, it seems that we now emit line number programs that can result in GDB and LLDB stopping inside the prologue when doing line number stepping into functions. See PR40188 for more information. A summary of some of the changed test cases is available in PR40188#c2. Reviewers: aprantl, dblaikie, rnk, jmorse Reviewed By: aprantl Subscribers: jdoerfert, jholewinski, jvesely, javed.absar, llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D57511 llvm-svn: 353928
2019-02-13 17:34:07 +08:00
; CHECK-NEXT: [0x0000000000000003, 0x0000000000000004): DW_OP_breg0 RAX+0, DW_OP_constu 0xffffffff, DW_OP_and, DW_OP_lit1, DW_OP_minus, DW_OP_stack_value
PR32382: Fix emitting complex DWARF expressions. The DWARF specification knows 3 kinds of non-empty simple location descriptions: 1. Register location descriptions - describe a variable in a register - consist of only a DW_OP_reg 2. Memory location descriptions - describe the address of a variable 3. Implicit location descriptions - describe the value of a variable - end with DW_OP_stack_value & friends The existing DwarfExpression code is pretty much ignorant of these restrictions. This used to not matter because we only emitted very short expressions that we happened to get right by accident. This patch makes DwarfExpression aware of the rules defined by the DWARF standard and now chooses the right kind of location description for each expression being emitted. This would have been an NFC commit (for the existing testsuite) if not for the way that clang describes captured block variables. Based on how the previous code in LLVM emitted locations, DW_OP_deref operations that should have come at the end of the expression are put at its beginning. Fixing this means changing the semantics of DIExpression, so this patch bumps the version number of DIExpression and implements a bitcode upgrade. There are two major changes in this patch: I had to fix the semantics of dbg.declare for describing function arguments. After this patch a dbg.declare always takes the *address* of a variable as the first argument, even if the argument is not an alloca. When lowering a DBG_VALUE, the decision of whether to emit a register location description or a memory location description depends on the MachineLocation — register machine locations may get promoted to memory locations based on their DIExpression. (Future) optimization passes that want to salvage implicit debug location for variables may do so by appending a DW_OP_stack_value. For example: DBG_VALUE, [RBP-8] --> DW_OP_fbreg -8 DBG_VALUE, RAX --> DW_OP_reg0 +0 DBG_VALUE, RAX, DIExpression(DW_OP_deref) --> DW_OP_reg0 +0 All testcases that were modified were regenerated from clang. I also added source-based testcases for each of these to the debuginfo-tests repository over the last week to make sure that no synchronized bugs slip in. The debuginfo-tests compile from source and run the debugger. https://bugs.llvm.org/show_bug.cgi?id=32382 <rdar://problem/31205000> Differential Revision: https://reviews.llvm.org/D31439 llvm-svn: 300522
2017-04-18 09:21:53 +08:00
; rax+0, constu 0xffffffff, and, constu 0x00000001, minus, stack-value
[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
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
source_filename = "minus.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"
define i32 @inc(i32 %i) local_unnamed_addr #1 !dbg !7 {
entry:
%add = add nsw i32 %i, 1, !dbg !15
Remove the obsolete offset parameter from @llvm.dbg.value There is no situation where this rarely-used argument cannot be substituted with a DIExpression and removing it allows us to simplify the DWARF backend. Note that this patch does not yet remove any of the newly dead code. rdar://problem/33580047 Differential Revision: https://reviews.llvm.org/D35951 llvm-svn: 309426
2017-07-29 04:21:02 +08:00
tail call void @llvm.dbg.value(metadata i32 %add, metadata !12, metadata !13), !dbg !14
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
ret i32 %add, !dbg !16
}
Remove the obsolete offset parameter from @llvm.dbg.value There is no situation where this rarely-used argument cannot be substituted with a DIExpression and removing it allows us to simplify the DWARF backend. Note that this patch does not yet remove any of the newly dead code. rdar://problem/33580047 Differential Revision: https://reviews.llvm.org/D35951 llvm-svn: 309426
2017-07-29 04:21:02 +08:00
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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
attributes #1 = { 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 286322) (llvm/trunk 286305)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "minus.c", directory: "/tmp")
!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 286322) (llvm/trunk 286305)"}
[DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label. In order to set breakpoints on labels and list source code around labels, we need collect debug information for labels, i.e., label name, the function label belong, line number in the file, and the address label located. In order to keep these information in LLVM IR and to allow backend to generate debug information correctly. We create a new kind of metadata for labels, DILabel. The format of DILabel is !DILabel(scope: !1, name: "foo", file: !2, line: 3) We hope to keep debug information as much as possible even the code is optimized. So, we create a new kind of intrinsic for label metadata to avoid the metadata is eliminated with basic block. The intrinsic will keep existing if we keep it from optimized out. The format of the intrinsic is llvm.dbg.label(metadata !1) It has only one argument, that is the DILabel metadata. The intrinsic will follow the label immediately. Backend could get the label metadata through the intrinsic's parameter. We also create DIBuilder API for labels to be used by Frontend. Frontend could use createLabel() to allocate DILabel objects, and use insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR. Differential Revision: https://reviews.llvm.org/D45024 Patch by Hsiangkai Wang. llvm-svn: 331841
2018-05-09 10:40:45 +08:00
!7 = distinct !DISubprogram(name: "inc", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
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
!8 = !DISubroutineType(types: !9)
!9 = !{!10, !10}
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !{!12}
!12 = !DILocalVariable(name: "i", arg: 1, scope: !7, file: !1, line: 1, type: !10)
Align definition of DW_OP_plus with DWARF spec [3/3] Summary: This patch is part of 3 patches that together form a single patch, but must be introduced in stages in order not to break things. The way that LLVM interprets DW_OP_plus in DIExpression nodes is basically that of the DW_OP_plus_uconst operator since LLVM expects an unsigned constant operand. This unnecessarily restricts the DW_OP_plus operator, preventing it from being used to describe the evaluation of runtime values on the expression stack. These patches try to align the semantics of DW_OP_plus and DW_OP_minus with that of the DWARF definition, which pops two elements off the expression stack, performs the operation and pushes the result back on the stack. This is done in three stages: • The first patch (LLVM) adds support for DW_OP_plus_uconst. • The second patch (Clang) contains changes all its uses from DW_OP_plus to DW_OP_plus_uconst. • The third patch (LLVM) changes the semantics of DW_OP_plus and DW_OP_minus to be in line with its DWARF meaning. This patch includes the bitcode upgrade from legacy DIExpressions. Patch by Sander de Smalen. Reviewers: echristo, pcc, aprantl Reviewed By: aprantl Subscribers: fhahn, javed.absar, aprantl, llvm-commits Differential Revision: https://reviews.llvm.org/D33894 llvm-svn: 305386
2017-06-14 21:14:38 +08:00
!13 = !DIExpression(DW_OP_constu, 1, DW_OP_minus, DW_OP_stack_value)
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
!14 = !DILocation(line: 1, column: 13, scope: !7)
!15 = !DILocation(line: 2, column: 11, scope: !7)
!16 = !DILocation(line: 2, column: 3, scope: !7)