thr3ads.net - llvm dev - [LLVMdev] How to get the variable mapping between the source and llvm bytecode [May 2010]

If this information is useful, please help other people find it:
Share via:

Kecheng

2010-May-13 20:47 UTC

[LLVMdev] How to get the variable mapping between the source and llvm bytecode

Hi,  

I want to know the variable mapping between the source and llvm bytecode. It
seems that current llvm debugging information cannot provide this mapping
directly.

Here is my examples (llvm 2.7). In this exmaple, I want to know the mapping:
tmp<--->%4. But current llvm's debugging information can only provide
that the instruction "%4 = add nsw i32 %3, 2" is at line 3 in the C
source. But since there're two "+" at line 3, I don't have a
direct way to know which "+" is mapped to this "add". Is
there any way I can derive the mapping based on current ddg infor? Thanks.

**************
C source
**************
int h (int j, int i) {
    int tmp;
    tmp = j+i+2;
    return tmp;
}

**************
.ll file 
**************
; ModuleID = 'simplecase.c'
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-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-unknown-linux-gnu"
define i32 @h(i32 %j, i32 %i) nounwind {
entry:
  %j_addr = alloca i32                            ; <i32*> [#uses=2]
  %i_addr = alloca i32                            ; <i32*> [#uses=2]
  %retval = alloca i32                            ; <i32*> [#uses=2]
  %0 = alloca i32                                 ; <i32*> [#uses=2]
  %tmp = alloca i32                               ; <i32*> [#uses=2]
  %"alloca point" = bitcast i32 0 to i32          ; <i32>
[#uses=0]
  call void @llvm.dbg.declare(metadata !{i32* %j_addr}, metadata !0), !dbg !6
  store i32 %j, i32* %j_addr
  call void @llvm.dbg.declare(metadata !{i32* %i_addr}, metadata !7), !dbg !6
  store i32 %i, i32* %i_addr
  call void @llvm.dbg.declare(metadata !{i32* %tmp}, metadata !8), !dbg !10
  %1 = load i32* %j_addr, align 4, !dbg !11       ; <i32> [#uses=1]
  %2 = load i32* %i_addr, align 4, !dbg !11       ; <i32> [#uses=1]
  %3 = add nsw i32 %1, %2, !dbg !11               ; <i32> [#uses=1]
  %4 = add nsw i32 %3, 2, !dbg !11                ; <i32> [#uses=1]
  store i32 %4, i32* %tmp, align 4, !dbg !11
  %5 = load i32* %tmp, align 4, !dbg !12          ; <i32> [#uses=1]
  store i32 %5, i32* %0, align 4, !dbg !12
  %6 = load i32* %0, align 4, !dbg !12            ; <i32> [#uses=1]
  store i32 %6, i32* %retval, align 4, !dbg !12
  br label %return, !dbg !12
return:                                           ; preds = %entry
  %retval1 = load i32* %retval, !dbg !12          ; <i32> [#uses=1]
  ret i32 %retval1, !dbg !12
}
declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
!0 = metadata !{i32 459009, metadata !1, metadata !"j", metadata !2,
i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
!1 = metadata !{i32 458798, i32 0, metadata !2, metadata !"h",
metadata !"h", metadata !"h", metadata !2, i32 1, metadata
!3, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [ DW_TAG_subprogram ]
!2 = metadata !{i32 458769, i32 0, i32 1, metadata !"simplecase.c",
metadata !"/home/kecheng/cases/v2.7/simplecase/", metadata
!"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 true, i1
false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
!3 = metadata !{i32 458773, metadata !2, metadata !"", metadata !2,
i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !4, i32 0, null} ; [
DW_TAG_subroutine_type ]
!4 = metadata !{metadata !5, metadata !5, metadata !5}
!5 = metadata !{i32 458788, metadata !2, metadata !"int", metadata !2,
i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
!6 = metadata !{i32 1, i32 0, metadata !1, null}
!7 = metadata !{i32 459009, metadata !1, metadata !"i", metadata !2,
i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
!8 = metadata !{i32 459008, metadata !9, metadata !"tmp", metadata !2,
i32 2, metadata !5} ; [ DW_TAG_auto_variable ]
!9 = metadata !{i32 458763, metadata !1, i32 1, i32 0} ; [ DW_TAG_lexical_block
]
!10 = metadata !{i32 1, i32 0, metadata !9, null}
!11 = metadata !{i32 3, i32 0, metadata !9, null}
!12 = metadata !{i32 4, i32 0, metadata !9, null}

Best,

Kecheng
2010-05-13
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20100513/485be9ba/attachment.html>

Eli Friedman

2010-May-13 22:38 UTC

head link

[LLVMdev] How to get the variable mapping between the source and llvm bytecode

On Thu, May 13, 2010 at 1:47 PM, Kecheng <kecheng at cecs.pdx.edu>
wrote:> Hi,
>
> I want to know the variable mapping between the source and llvm bytecode.
It
> seems that current llvm debugging information cannot provide this mapping
> directly.
>
> Here is my examples (llvm 2.7). In this exmaple, I want to know the
mapping:
> tmp<--->%4. But current llvm's debugging information can only
provide that
> the instruction "%4 = add nsw i32 %3, 2" is at line 3 in the C
source. But
> since there're two "+" at line 3, I don't have a direct
way to know which
> "+" is mapped to this "add". Is there any way I can
derive the mapping based
> on current ddg infor? Thanks.
You want to map the "+" in the source to a specific "add"
instruction?
 clang does provide column number info, though, which might help a
bit.  In general, though, debug info isn't rich enough to provide that
sort of mapping.  What are you trying to do?

-Eli
> **************
> C source
> **************
> int h (int j, int i) {
>     int tmp;
>     tmp = j+i+2;
>     return tmp;
> }
>
> **************
> .ll file
> **************
> ; ModuleID = 'simplecase.c'
>
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-s0:64:64-f80:128:128-n8:16:32:64"
> target triple = "x86_64-unknown-linux-gnu"
> define i32 @h(i32 %j, i32 %i) nounwind {
> entry:
>   %j_addr = alloca i32                            ; <i32*> [#uses=2]
>   %i_addr = alloca i32                            ; <i32*> [#uses=2]
>   %retval = alloca i32                            ; <i32*> [#uses=2]
>   %0 = alloca i32                                 ; <i32*> [#uses=2]
>   %tmp = alloca i32                               ; <i32*> [#uses=2]
>
  %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
>
  call void @llvm.dbg.declare(metadata !{i32* %j_addr}, metadata !0), !dbg !6
>   store i32 %j, i32* %j_addr
>
  call void @llvm.dbg.declare(metadata !{i32* %i_addr}, metadata !7), !dbg !6
>   store i32 %i, i32* %i_addr
>   call void @llvm.dbg.declare(metadata !{i32* %tmp}, metadata !8), !dbg !10
>   %1 = load i32* %j_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>   %2 = load i32* %i_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>   %3 = add nsw i32 %1, %2, !dbg !11               ; <i32> [#uses=1]
>   %4 = add nsw i32 %3, 2, !dbg !11                ; <i32> [#uses=1]
>   store i32 %4, i32* %tmp, align 4, !dbg !11
>   %5 = load i32* %tmp, align 4, !dbg !12          ; <i32> [#uses=1]
>   store i32 %5, i32* %0, align 4, !dbg !12
>   %6 = load i32* %0, align 4, !dbg !12            ; <i32> [#uses=1]
>   store i32 %6, i32* %retval, align 4, !dbg !12
>   br label %return, !dbg !12
> return:                                           ; preds = %entry
>   %retval1 = load i32* %retval, !dbg !12          ; <i32> [#uses=1]
>   ret i32 %retval1, !dbg !12
> }
> declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
>
!0 = metadata !{i32 459009, metadata !1, metadata !"j", metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>
!1 = metadata !{i32 458798, i32 0, metadata !2, metadata !"h", metadata !"h", metadata !"h", metadata !2, i32 1, metadata !3, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [ DW_TAG_subprogram ]
>
!2 = metadata !{i32 458769, i32 0, i32 1, metadata !"simplecase.c", metadata !"/home/kecheng/cases/v2.7/simplecase/", metadata !"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 true, i1 false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
>
!3 = metadata !{i32 458773, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !4, i32 0, null} ; [ DW_TAG_subroutine_type ]
> !4 = metadata !{metadata !5, metadata !5, metadata !5}
>
!5 = metadata !{i32 458788, metadata !2, metadata !"int", metadata !2, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
> !6 = metadata !{i32 1, i32 0, metadata !1, null}
>
!7 = metadata !{i32 459009, metadata !1, metadata !"i", metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>
!8 = metadata !{i32 459008, metadata !9, metadata !"tmp", metadata !2, i32 2, metadata !5} ; [ DW_TAG_auto_variable ]
>
!9 = metadata !{i32 458763, metadata !1, i32 1, i32 0} ; [ DW_TAG_lexical_block ]
> !10 = metadata !{i32 1, i32 0, metadata !9, null}
> !11 = metadata !{i32 3, i32 0, metadata !9, null}
> !12 = metadata !{i32 4, i32 0, metadata !9, null}
>
> Best,
>
> Kecheng
> 2010-05-13
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>

Kecheng

2010-May-13 23:00 UTC

head link

[LLVMdev] How to get the variable mapping between the source andllvm bytecode

Hi,

I want to get the mapping between C source's variables and bytecode
variables.  It seems that llvm doesn't provide this mapping, so I think a
walk-around method is to get the instruction's mapping. I have to use
llvm-gcc, not clang. Any advice? Thanks.

Best,




Kecheng
2010-05-13



From: Eli Friedman
Date: 2010-05-13 15:38:36
To: Kecheng
Cc: llvmdev
Subject: Re: [LLVMdev] How to get the variable mapping between the source
andllvm bytecode

On Thu, May 13, 2010 at 1:47 PM, Kecheng <kecheng at cecs.pdx.edu>
wrote:> Hi,
>
> I want to know the variable mapping between the source and llvm bytecode.
It
> seems that current llvm debugging information cannot provide this mapping
> directly.
>
> Here is my examples (llvm 2.7). In this exmaple, I want to know the
mapping:
> tmp<--->%4. But current llvm's debugging information can only
provide that
> the instruction "%4 = add nsw i32 %3, 2" is at line 3 in the C
source. But
> since there're two "+" at line 3, I don't have a direct
way to know which
> "+" is mapped to this "add". Is there any way I can
derive the mapping based
> on current ddg infor? Thanks.You want to map the "+" in the source to a specific "add"
instruction?
 clang does provide column number info, though, which might help a
bit.  In general, though, debug info isn't rich enough to provide that
sort of mapping.  What are you trying to do?
-Eli> **************
> C source
> **************
> int h (int j, int i) {
>     int tmp;
>     tmp = j+i+2;
>     return tmp;
> }
>
> **************
> .ll file
> **************
> ; ModuleID = 'simplecase.c'
> 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-s0:64:64-f80:128:128-n8:16:32:64"
> target triple = "x86_64-unknown-linux-gnu"
> define i32 @h(i32 %j, i32 %i) nounwind {
> entry:
>   %j_addr = alloca i32                            ; <i32*> [#uses=2]
>   %i_addr = alloca i32                            ; <i32*> [#uses=2]
>   %retval = alloca i32                            ; <i32*> [#uses=2]
>   %0 = alloca i32                                 ; <i32*> [#uses=2]
>   %tmp = alloca i32                               ; <i32*> [#uses=2]
>   %"alloca point" = bitcast i32 0 to i32          ; <i32>
[#uses=0]
>   call void @llvm.dbg.declare(metadata !{i32* %j_addr}, metadata !0), !dbg
!6
>   store i32 %j, i32* %j_addr
>   call void @llvm.dbg.declare(metadata !{i32* %i_addr}, metadata !7), !dbg
!6
>   store i32 %i, i32* %i_addr
>   call void @llvm.dbg.declare(metadata !{i32* %tmp}, metadata !8), !dbg !10
>   %1 = load i32* %j_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>   %2 = load i32* %i_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>   %3 = add nsw i32 %1, %2, !dbg !11               ; <i32> [#uses=1]
>   %4 = add nsw i32 %3, 2, !dbg !11                ; <i32> [#uses=1]
>   store i32 %4, i32* %tmp, align 4, !dbg !11
>   %5 = load i32* %tmp, align 4, !dbg !12          ; <i32> [#uses=1]
>   store i32 %5, i32* %0, align 4, !dbg !12
>   %6 = load i32* %0, align 4, !dbg !12            ; <i32> [#uses=1]
>   store i32 %6, i32* %retval, align 4, !dbg !12
>   br label %return, !dbg !12
> return:                                           ; preds = %entry
>   %retval1 = load i32* %retval, !dbg !12          ; <i32> [#uses=1]
>   ret i32 %retval1, !dbg !12
> }
> declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
> !0 = metadata !{i32 459009, metadata !1, metadata !"j", metadata
!2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
> !1 = metadata !{i32 458798, i32 0, metadata !2, metadata !"h",
metadata !"h", metadata !"h", metadata !2, i32 1, metadata
!3, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [ DW_TAG_subprogram ]
> !2 = metadata !{i32 458769, i32 0, i32 1, metadata
!"simplecase.c", metadata
!"/home/kecheng/cases/v2.7/simplecase/", metadata !"4.2.1 (Based
on Apple Inc. build 5658) (LLVM build)", i1 true, i1 false, metadata
!"", i32 0} ; [ DW_TAG_compile_unit ]
> !3 = metadata !{i32 458773, metadata !2, metadata !"", metadata
!2, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !4, i32 0, null} ; [
DW_TAG_subroutine_type ]
> !4 = metadata !{metadata !5, metadata !5, metadata !5}
> !5 = metadata !{i32 458788, metadata !2, metadata !"int",
metadata !2, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
> !6 = metadata !{i32 1, i32 0, metadata !1, null}
> !7 = metadata !{i32 459009, metadata !1, metadata !"i", metadata
!2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
> !8 = metadata !{i32 459008, metadata !9, metadata !"tmp",
metadata !2, i32 2, metadata !5} ; [ DW_TAG_auto_variable ]
> !9 = metadata !{i32 458763, metadata !1, i32 1, i32 0} ; [
DW_TAG_lexical_block ]
> !10 = metadata !{i32 1, i32 0, metadata !9, null}
> !11 = metadata !{i32 3, i32 0, metadata !9, null}
> !12 = metadata !{i32 4, i32 0, metadata !9, null}
>
> Best,
>
> Kecheng
> 2010-05-13
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20100513/e28a70d7/attachment.html>

Eli Friedman

2010-May-13 23:58 UTC

head link

[LLVMdev] How to get the variable mapping between the source andllvm bytecode

On Thu, May 13, 2010 at 4:00 PM, Kecheng <kecheng at cecs.pdx.edu>
wrote:> Hi,
>
> I want to get the mapping between C source's variables and bytecode
> variables.  It seems that llvm doesn't provide this mapping, so I think
a
> walk-around method is to get the instruction's mapping. I have to use
> llvm-gcc, not clang. Any advice? Thanks.
"int tmp;" corresponds to "%tmp = alloca i32" in the IR. 
You can pull
that mapping out of the appropriate llvm.dbg.declare call.  To find
assignments to the variable, look for store instructions which store
into "%tmp".  I fail to see what the addition has to do with anything
in this context.

-Eli
> Best,
>
> ________________________________
> Kecheng
> 2010-05-13
> ________________________________
> From： Eli Friedman
> Date： 2010-05-13 15:38:36
> To： Kecheng
> Cc： llvmdev
> Subject： Re: [LLVMdev] How to get the variable mapping between the source
> andllvm bytecode
>
> On Thu, May 13, 2010 at 1:47 PM, Kecheng <kecheng at
cecs.pdx.edu> wrote:
>> Hi,
>>
>> I want to know the variable mapping between the source and llvm bytecode. It
>> seems that current llvm debugging information cannot provide this mapping
>> directly.
>>
>> Here is my examples (llvm 2.7). In this exmaple, I want to know the mapping:
>> tmp<--->%4. But current llvm's debugging information can only provide that
>> the instruction "%4 = add nsw i32 %3, 2" is at line 3 in the C source. But
>> since there're two "+" at line 3, I don't have a direct way to know which
>> "+" is mapped to this "add". Is there any way I can derive the mapping based
>> on current ddg infor? Thanks.
>
You want to map the "+" in the source to a specific "add" instruction?
>  clang does provide column number info, though, which might help a
> bit.  In general, though, debug info isn't rich enough to provide that
> sort of mapping.  What are you trying to do?
> -Eli
>> **************
>> C source
>> **************
>> int h (int j, int i) {
>>     int tmp;
>>     tmp = j+i+2;
>>     return tmp;
>> }
>>
>> **************
>> .ll file
>> **************
>> ; ModuleID = 'simplecase.c'
>> 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-s0:64:64-f80:128:128-n8:16:32:64"
>> target triple = "x86_64-unknown-linux-gnu"
>> define i32 @h(i32 %j, i32 %i) nounwind {
>> entry:
>>   %j_addr = alloca i32                            ; <i32*> [#uses=2]
>>   %i_addr = alloca i32                            ; <i32*> [#uses=2]
>>   %retval = alloca i32                            ; <i32*> [#uses=2]
>>   %0 = alloca i32                                 ; <i32*> [#uses=2]
>>   %tmp = alloca i32                               ; <i32*> [#uses=2]
>>   %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
>>   call void @llvm.dbg.declare(metadata !{i32* %j_addr}, metadata !0), !dbg !6
>>   store i32 %j, i32* %j_addr
>>   call void @llvm.dbg.declare(metadata !{i32* %i_addr}, metadata !7), !dbg !6
>>   store i32 %i, i32* %i_addr
>>   call void @llvm.dbg.declare(metadata !{i32* %tmp}, metadata !8), !dbg !10
>>   %1 = load i32* %j_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>>   %2 = load i32* %i_addr, align 4, !dbg !11       ; <i32> [#uses=1]
>>   %3 = add nsw i32 %1, %2, !dbg !11               ; <i32> [#uses=1]
>>   %4 = add nsw i32 %3, 2, !dbg !11                ; <i32> [#uses=1]
>>   store i32 %4, i32* %tmp, align 4, !dbg !11
>>   %5 = load i32* %tmp, align 4, !dbg !12          ; <i32> [#uses=1]
>>   store i32 %5, i32* %0, align 4, !dbg !12
>>   %6 = load i32* %0, align 4, !dbg !12            ; <i32> [#uses=1]
>>   store i32 %6, i32* %retval, align 4, !dbg !12
>>   br label %return, !dbg !12
>> return:                                           ; preds = %entry
>>   %retval1 = load i32* %retval, !dbg !12          ; <i32> [#uses=1]
>>   ret i32 %retval1, !dbg !12
>> }
>> declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
>> !0 = metadata !{i32 459009, metadata !1, metadata !"j", metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>> !1 = metadata !{i32 458798, i32 0, metadata !2, metadata !"h", metadata !"h", metadata !"h", metadata !2, i32 1, metadata !3, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [ DW_TAG_subprogram ]
>> !2 = metadata !{i32 458769, i32 0, i32 1, metadata !"simplecase.c", metadata !"/home/kecheng/cases/v2.7/simplecase/", metadata !"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 true, i1 false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
>> !3 = metadata !{i32 458773, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !4, i32 0, null} ; [ DW_TAG_subroutine_type ]
>> !4 = metadata !{metadata !5, metadata !5, metadata !5}
>> !5 = metadata !{i32 458788, metadata !2, metadata !"int", metadata !2, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
>> !6 = metadata !{i32 1, i32 0, metadata !1, null}
>> !7 = metadata !{i32 459009, metadata !1, metadata !"i", metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>> !8 = metadata !{i32 459008, metadata !9, metadata !"tmp", metadata !2, i32 2, metadata !5} ; [ DW_TAG_auto_variable ]
>> !9 = metadata !{i32 458763, metadata !1, i32 1, i32 0} ; [ DW_TAG_lexical_block ]
>> !10 = metadata !{i32 1, i32 0, metadata !9, null}
>> !11 = metadata !{i32 3, i32 0, metadata !9, null}
>> !12 = metadata !{i32 4, i32 0, metadata !9, null}
>>
>> Best,
>>
>> Kecheng
>> 2010-05-13
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>

Kecheng

2010-May-14 01:18 UTC

head link

[LLVMdev] How to get the variable mapping between the sourceandllvm bytecode

Eli,

Thanks very much for your reply. That's what I want to know. It works for
this example. But I usually have to deal with the optimized bytecode with
"-O".
See the example: 


**************
C source
**************
int h (int j, int i) {
    int tmp;
    tmp = j+i+2;
    return tmp;
}

+++++++++++++++++++++++++++++++++++++
.ll file:


; ModuleID = 'simplecase.c'
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-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-unknown-linux-gnu"
define i32 @h(i32 %j, i32 %i) nounwind readnone {
entry:
  %0 = add nsw i32 %j, 2, !dbg !0                 ; <i32> [#uses=1]
  %1 = add nsw i32 %0, %i, !dbg !0                ; <i32> [#uses=1]
  ret i32 %1, !dbg !7
}
!0 = metadata !{i32 3, i32 0, metadata !1, null}
!1 = metadata !{i32 458763, metadata !2, i32 1, i32 0} ; [ DW_TAG_lexical_block
]
!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"h",
metadata !"h", metadata !"h", metadata !3, i32 1, metadata
!4, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [ DW_TAG_subprogram ]
!3 = metadata !{i32 458769, i32 0, i32 1, metadata !"simplecase.c",
metadata !"/home/kecheng/cases/v2.7/simplecase/", metadata
!"4.2.1 (Based on Apple Inc. build 5658) (LLVM build)", i1 true, i1
true, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
!4 = metadata !{i32 458773, metadata !3, metadata !"", metadata !3,
i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !5, i32 0, null} ; [
DW_TAG_subroutine_type ]
!5 = metadata !{metadata !6, metadata !6, metadata !6}
!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3,
i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
!7 = metadata !{i32 4, i32 0, metadata !1, null}
+++++++++++++++++++++++++++++++++++++

Now the mapping will be tmp <---->%1. We can't derive the mapping
based on "alloca/store" instruction.



Best,






Kecheng
2010-05-13



From： Eli Friedman
Date： 2010-05-13 16:58:05
To： Kecheng
Cc： llvmdev
Subject： Re: Re: [LLVMdev] How to get the variable mapping between the
sourceandllvm bytecode

On Thu, May 13, 2010 at 4:00 PM, Kecheng <kecheng at cecs.pdx.edu>
wrote:> Hi,
>
> I want to get the mapping between C source's variables and bytecode
> variables.  It seems that llvm doesn't provide this mapping, so I think
a
> walk-around method is to get the instruction's mapping. I have to use
> llvm-gcc, not clang. Any advice? Thanks."int tmp;" corresponds to "%tmp = alloca i32" in the IR. 
You can pull
that mapping out of the appropriate llvm.dbg.declare call.  To find
assignments to the variable, look for store instructions which store
into "%tmp".  I fail to see what the addition has to do with anything
in this context.
-Eli> Best,
>
> ________________________________
> Kecheng
> 2010-05-13
> ________________________________
> From： Eli Friedman
> Date： 2010-05-13 15:38:36
> To： Kecheng
> Cc： llvmdev
> Subject： Re: [LLVMdev] How to get the variable mapping between the source
> andllvm bytecode
>
> On Thu, May 13, 2010 at 1:47 PM, Kecheng <kecheng at cecs.pdx.edu>
wrote:
>> Hi,
>>
>> I want to know the variable mapping between the source and llvm
bytecode. It
>> seems that current llvm debugging information cannot provide this
mapping
>> directly.
>>
>> Here is my examples (llvm 2.7). In this exmaple, I want to know the
mapping:
>> tmp<--->%4. But current llvm's debugging information can only
provide that
>> the instruction "%4 = add nsw i32 %3, 2" is at line 3 in the
C source. But
>> since there're two "+" at line 3, I don't have a
direct way to know which
>> "+" is mapped to this "add". Is there any way I can
derive the mapping based
>> on current ddg infor? Thanks.
> You want to map the "+" in the source to a specific
"add" instruction?
>  clang does provide column number info, though, which might help a
> bit.  In general, though, debug info isn't rich enough to provide that
> sort of mapping.  What are you trying to do?
> -Eli
>> **************
>> C source
>> **************
>> int h (int j, int i) {
>>     int tmp;
>>     tmp = j+i+2;
>>     return tmp;
>> }
>>
>> **************
>> .ll file
>> **************
>> ; ModuleID = 'simplecase.c'
>> 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-s0:64:64-f80:128:128-n8:16:32:64"
>> target triple = "x86_64-unknown-linux-gnu"
>> define i32 @h(i32 %j, i32 %i) nounwind {
>> entry:
>>   %j_addr = alloca i32                            ; <i32*>
[#uses=2]
>>   %i_addr = alloca i32                            ; <i32*>
[#uses=2]
>>   %retval = alloca i32                            ; <i32*>
[#uses=2]
>>   %0 = alloca i32                                 ; <i32*>
[#uses=2]
>>   %tmp = alloca i32                               ; <i32*>
[#uses=2]
>>   %"alloca point" = bitcast i32 0 to i32          ;
<i32> [#uses=0]
>>   call void @llvm.dbg.declare(metadata !{i32* %j_addr}, metadata !0),
!dbg !6
>>   store i32 %j, i32* %j_addr
>>   call void @llvm.dbg.declare(metadata !{i32* %i_addr}, metadata !7),
!dbg !6
>>   store i32 %i, i32* %i_addr
>>   call void @llvm.dbg.declare(metadata !{i32* %tmp}, metadata !8), !dbg
!10
>>   %1 = load i32* %j_addr, align 4, !dbg !11       ; <i32>
[#uses=1]
>>   %2 = load i32* %i_addr, align 4, !dbg !11       ; <i32>
[#uses=1]
>>   %3 = add nsw i32 %1, %2, !dbg !11               ; <i32>
[#uses=1]
>>   %4 = add nsw i32 %3, 2, !dbg !11                ; <i32>
[#uses=1]
>>   store i32 %4, i32* %tmp, align 4, !dbg !11
>>   %5 = load i32* %tmp, align 4, !dbg !12          ; <i32>
[#uses=1]
>>   store i32 %5, i32* %0, align 4, !dbg !12
>>   %6 = load i32* %0, align 4, !dbg !12            ; <i32>
[#uses=1]
>>   store i32 %6, i32* %retval, align 4, !dbg !12
>>   br label %return, !dbg !12
>> return:                                           ; preds = %entry
>>   %retval1 = load i32* %retval, !dbg !12          ; <i32>
[#uses=1]
>>   ret i32 %retval1, !dbg !12
>> }
>> declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
>> !0 = metadata !{i32 459009, metadata !1, metadata !"j",
metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>> !1 = metadata !{i32 458798, i32 0, metadata !2, metadata
!"h", metadata !"h", metadata !"h", metadata !2,
i32 1, metadata !3, i1 false, i1 true, i32 0, i32 0, null, i1 false} ; [
DW_TAG_subprogram ]
>> !2 = metadata !{i32 458769, i32 0, i32 1, metadata
!"simplecase.c", metadata
!"/home/kecheng/cases/v2.7/simplecase/", metadata !"4.2.1 (Based
on Apple Inc. build 5658) (LLVM build)", i1 true, i1 false, metadata
!"", i32 0} ; [ DW_TAG_compile_unit ]
>> !3 = metadata !{i32 458773, metadata !2, metadata !"",
metadata !2, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !4, i32 0, null}
; [ DW_TAG_subroutine_type ]
>> !4 = metadata !{metadata !5, metadata !5, metadata !5}
>> !5 = metadata !{i32 458788, metadata !2, metadata !"int",
metadata !2, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
>> !6 = metadata !{i32 1, i32 0, metadata !1, null}
>> !7 = metadata !{i32 459009, metadata !1, metadata !"i",
metadata !2, i32 1, metadata !5} ; [ DW_TAG_arg_variable ]
>> !8 = metadata !{i32 459008, metadata !9, metadata !"tmp",
metadata !2, i32 2, metadata !5} ; [ DW_TAG_auto_variable ]
>> !9 = metadata !{i32 458763, metadata !1, i32 1, i32 0} ; [
DW_TAG_lexical_block ]
>> !10 = metadata !{i32 1, i32 0, metadata !9, null}
>> !11 = metadata !{i32 3, i32 0, metadata !9, null}
>> !12 = metadata !{i32 4, i32 0, metadata !9, null}
>>
>> Best,
>>
>> Kecheng
>> 2010-05-13
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20100513/19ad8619/attachment.html>

Apparently Analagous Threads

Search for more reasonably related threads

llvm dev - May 2010 - [LLVMdev] How to get the variable mapping between the source and llvm bytecode

[LLVMdev] How to get the variable mapping between the source and llvm bytecode

[LLVMdev] How to get the variable mapping between the source and llvm bytecode

[LLVMdev] How to get the variable mapping between the source andllvm bytecode

[LLVMdev] How to get the variable mapping between the source andllvm bytecode

[LLVMdev] How to get the variable mapping between the sourceandllvm bytecode

Apparently Analagous Threads