[llvm] r223799 - Correctly handle complex locations expressions in replaceDbgDeclareForAlloca()

Tue Dec 9 10:11:31 PST 2014

On Tue, Dec 9, 2014 at 9:55 AM, Frederic Riss <friss at apple.com> wrote:

> Author: friss
> Date: Tue Dec  9 11:55:48 2014
> New Revision: 223799
>
> URL: http://llvm.org/viewvc/llvm-project?rev=223799&view=rev
> Log:
> Correctly handle complex locations expressions in
> replaceDbgDeclareForAlloca()
>
> replaceDbgDeclareForAlloca() replaces an alloca by a value storing the
> address of what was the alloca. If there is a dbg.declare corresponding
> to that alloca, we need to lower it to a dbg.value describing the
> additional
> dereference operation to be performed to get to the underlying variable.
>  This is done by adding a DW_OP_deref to the complex location part of the
> location description. This deref was added to the end of the operation
> list,
> which is wrong. The expression applies to what is described by the
> dbg.{declare,value}, and as we are changing this, we need to apply the
> DW_OP_deref as the first operation in the list.
>
> Part of the fix for rdar://19162268.
>
> Added:
>     llvm/trunk/test/DebugInfo/block-asan.ll
> Modified:
>     llvm/trunk/lib/Transforms/Utils/Local.cpp
>
> Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=223799&r1=223798&r2=223799&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/Local.cpp Tue Dec  9 11:55:48 2014
> @@ -1111,7 +1111,7 @@ bool llvm::replaceDbgDeclareForAlloca(Al
>    if (!DIVar)
>      return false;
>
> -  // Create a copy of the original DIDescriptor for user variable,
> appending
> +  // Create a copy of the original DIDescriptor for user variable,
> prepending
>    // "deref" operation to a list of address elements, as new
> llvm.dbg.declare
>    // will take a value storing address of the memory for variable, not
>    // alloca itself.
> @@ -1121,7 +1121,7 @@ bool llvm::replaceDbgDeclareForAlloca(Al
>        NewDIExpr.push_back(DIExpr.getElement(i));
>      }
>    }
> -  NewDIExpr.push_back(dwarf::DW_OP_deref);
> +  NewDIExpr.insert(NewDIExpr.begin(), dwarf::DW_OP_deref);
>

Could we move this to before the loop, so we don't have to shift everything
up in the vector to make space for this new first element?

>
>    // Insert llvm.dbg.declare in the same basic block as the original
> alloca,
>    // and remove old llvm.dbg.declare.
>
> Added: llvm/trunk/test/DebugInfo/block-asan.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/block-asan.ll?rev=223799&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/block-asan.ll (added)
> +++ llvm/trunk/test/DebugInfo/block-asan.ll Tue Dec  9 11:55:48 2014
> @@ -0,0 +1,87 @@
> +; RUN: opt -S -asan %s | FileCheck %s
> +
> +; The IR of this testcase is generated from the following C code:
> +; void bar (int);
> +;
> +; void foo() {
> +;   __block int x;
> +;   bar(x);
> +; }
> +; by compiling it with 'clang -emit-llvm -g -S' and then by manually
> +; adding the sanitize_address attribute to the @foo() function (so
> +; that ASAN accepts to instrument the function in the above opt run).
> +
> +; Check that the location of the ASAN instrumented __block variable is
> +; correct.
> +; CHECK: [ DW_TAG_expression ] [DW_OP_deref] [DW_OP_plus 8] [DW_OP_deref]
> [DW_OP_plus 24]
> +
> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
> +
> +%struct.__block_byref_x = type { i8*, %struct.__block_byref_x*, i32, i32,
> i32 }
> +
> +; Function Attrs: nounwind ssp uwtable
> +define void @foo() #0 {
> +entry:
> +  %x = alloca %struct.__block_byref_x, align 8
> +  call void @llvm.dbg.declare(metadata !{%struct.__block_byref_x* %x},
> metadata !12, metadata !22), !dbg !23
> +  %byref.isa = getelementptr inbounds %struct.__block_byref_x* %x, i32 0,
> i32 0, !dbg !24
> +  store i8* null, i8** %byref.isa, !dbg !24
> +  %byref.forwarding = getelementptr inbounds %struct.__block_byref_x* %x,
> i32 0, i32 1, !dbg !24
> +  store %struct.__block_byref_x* %x, %struct.__block_byref_x**
> %byref.forwarding, !dbg !24
> +  %byref.flags = getelementptr inbounds %struct.__block_byref_x* %x, i32
> 0, i32 2, !dbg !24
> +  store i32 0, i32* %byref.flags, !dbg !24
> +  %byref.size = getelementptr inbounds %struct.__block_byref_x* %x, i32
> 0, i32 3, !dbg !24
> +  store i32 32, i32* %byref.size, !dbg !24
> +  %forwarding = getelementptr inbounds %struct.__block_byref_x* %x, i32
> 0, i32 1, !dbg !25
> +  %0 = load %struct.__block_byref_x** %forwarding, !dbg !25
> +  %x1 = getelementptr inbounds %struct.__block_byref_x* %0, i32 0, i32 4,
> !dbg !25
> +  %1 = load i32* %x1, align 4, !dbg !25
> +  call void @bar(i32 %1), !dbg !25
> +  %2 = bitcast %struct.__block_byref_x* %x to i8*, !dbg !26
> +  call void @_Block_object_dispose(i8* %2, i32 8) #3, !dbg !26
> +  ret void, !dbg !26
> +}
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
> +
> +declare void @bar(i32) #2
> +
> +declare void @_Block_object_dispose(i8*, i32)
> +
> +attributes #0 = { nounwind ssp uwtable sanitize_address
> "less-precise-fpmad"="false" "no-frame-pointer-elim"="true"
> "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false"
> "no-nans-fp-math"="false" "stack-protector-buffer-size"="8"
> "unsafe-fp-math"="false" "use-soft-float"="false" }
> +attributes #1 = { nounwind readnone }
> +attributes #2 = { "less-precise-fpmad"="false"
> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
> "no-infs-fp-math"="false" "no-nans-fp-math"="false"
> "stack-protector-buffer-size"="8" "unsafe-fp-math"="false"
> "use-soft-float"="false" }
> +attributes #3 = { nounwind }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!8, !9, !10}
> +!llvm.ident = !{!11}
> +
> +!0 = metadata !{metadata !"0x11\0012\00clang version 3.6.0 (trunk 223120)
> (llvm/trunk 223119)\000\00\000\00\001", metadata !1, metadata !2, metadata
> !2, metadata !3, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ]
> [/tmp/block.c] [DW_LANG_C99]
> +!1 = metadata !{metadata !"block.c", metadata !"/tmp"}
> +!2 = metadata !{}
> +!3 = metadata !{metadata !4}
> +!4 = metadata !{metadata
> !"0x2e\00foo\00foo\00\003\000\001\000\000\000\000\003", metadata !1,
> metadata !5, metadata !6, null, void ()* @foo, null, null, metadata !2} ; [
> DW_TAG_subprogram ] [line 3] [def] [foo]
> +!5 = metadata !{metadata !"0x29", metadata !1}    ; [ DW_TAG_file_type ]
> [/tmp/block.c]
> +!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null,
> null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0,
> size 0, align 0, offset 0] [from ]
> +!7 = metadata !{null}
> +!8 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
> +!9 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
> +!10 = metadata !{i32 1, metadata !"PIC Level", i32 2}
> +!11 = metadata !{metadata !"clang version 3.6.0 (trunk 223120)
> (llvm/trunk 223119)"}
> +!12 = metadata !{metadata !"0x100\00x\004\000", metadata !4, metadata !5,
> metadata !13} ; [ DW_TAG_auto_variable ] [x] [line 4]
> +!13 = metadata !{metadata !"0x13\00\000\00224\000\000\0016\000", metadata
> !1, metadata !5, null, metadata !14, null, null, null} ; [
> DW_TAG_structure_type ] [line 0, size 224, align 0, offset 0] [def] [from ]
> +!14 = metadata !{metadata !15, metadata !17, metadata !18, metadata !20,
> metadata !21}
> +!15 = metadata !{metadata !"0xd\00__isa\000\0064\0064\000\000", metadata
> !1, metadata !5, metadata !16} ; [ DW_TAG_member ] [__isa] [line 0, size
> 64, align 64, offset 0] [from ]
> +!16 = metadata !{metadata !"0xf\00\000\0064\0064\000\000", null, null,
> null} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from
> ]
> +!17 = metadata !{metadata !"0xd\00__forwarding\000\0064\0064\0064\000",
> metadata !1, metadata !5, metadata !16} ; [ DW_TAG_member ] [__forwarding]
> [line 0, size 64, align 64, offset 64] [from ]
> +!18 = metadata !{metadata !"0xd\00__flags\000\0032\0032\00128\000",
> metadata !1, metadata !5, metadata !19} ; [ DW_TAG_member ] [__flags] [line
> 0, size 32, align 32, offset 128] [from int]
> +!19 = metadata !{metadata !"0x24\00int\000\0032\0032\000\000\005", null,
> null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0,
> enc DW_ATE_signed]
> +!20 = metadata !{metadata !"0xd\00__size\000\0032\0032\00160\000",
> metadata !1, metadata !5, metadata !19} ; [ DW_TAG_member ] [__size] [line
> 0, size 32, align 32, offset 160] [from int]
> +!21 = metadata !{metadata !"0xd\00x\000\0032\0032\00192\000", metadata
> !1, metadata !5, metadata !19} ; [ DW_TAG_member ] [x] [line 0, size 32,
> align 32, offset 192] [from int]
> +!22 = metadata !{metadata !"0x102\0034\008\006\0034\0024"} ; [
> DW_TAG_expression ] [DW_OP_plus 8] [DW_OP_deref] [DW_OP_plus 24]
> +!23 = metadata !{i32 4, i32 15, metadata !4, null}
> +!24 = metadata !{i32 4, i32 3, metadata !4, null}
> +!25 = metadata !{i32 5, i32 3, metadata !4, null}
> +!26 = metadata !{i32 6, i32 1, metadata !4, null}
>
>
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