llvm dev - Nov 2008 - [LLVMdev] Writing instructions to file

Hello all,
I am instrumenting the code such that I write the results of some instructions
to file. As you can see below, I am writing the results of add instruction to
the file. The IR generated for writeToFile is also posted below. My problem is
that it is writing to the file in format bytes  and it is not human-readable.
How do I make it write human readable strings to the file?

define i32 @add(i32 %a, i32 %b) nounwind  {
entry:
	%tmp3 = add i32 %b, %a		; <i32> [#uses=2]
	alloca i32		; <i32*>:0 [#uses=2]
	store i32 %tmp3, i32* %0, align 4
	bitcast i32* %0 to i8*		; <i8*>:1 [#uses=1]
	tail call void @writeToFile( i8* %1 )
	ret i32 %tmp3
}

define void @writeToFile(i8* %str) {
entry:
	%tmp = tail call %struct.FILE* @fopen( i8* getelementptr ([8 x i8]* @.str, i32
0, i32 0), i8* getelementptr ([2 x i8]* @.str1, i32 0, i32 0) )		;
<%struct.FILE*> [#uses=3]
	%tmp2 = icmp eq %struct.FILE* %tmp, null		; <i1> [#uses=1]
	br i1 %tmp2, label %bb, label %bb5

bb:		; preds = %entry
	%tmp4 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([20 x i8]*
@.str2, i32 0, i32 0) )		; <i32> [#uses=0]
	ret void

bb5:		; preds = %entry
	%tmp8 = tail call i32 (%struct.FILE*, i8*, ...)* @fprintf( %struct.FILE* %tmp,
i8* %str )		; <i32> [#uses=0]
	%tmp10 = tail call i32 @fclose( %struct.FILE* %tmp )		; <i32> [#uses=0]
	ret void
}

declare %struct.FILE* @fopen(i8*, i8*)

declare i32 @printf(i8*, ...)

declare i32 @fprintf(%struct.FILE*, i8*, ...)

declare i32 @fclose(%struct.FILE*)

Thanks,
Bhavani

A good way to figure out how to represent things in IR is to write a C  
program that does what you want and then use llvm-gcc to see the  
instructions that are generated.

-Tanya

On Nov 17, 2008, at 8:30 PM, bhavani krishnan wrote:
> Hello all,
> I am instrumenting the code such that I write the results of some  
> instructions to file. As you can see below, I am writing the results  
> of add instruction to the file. The IR generated for writeToFile is  
> also posted below. My problem is that it is writing to the file in  
> format bytes  and it is not human-readable. How do I make it write  
> human readable strings to the file?
>
> define i32 @add(i32 %a, i32 %b) nounwind  {
> entry:
> 	%tmp3 = add i32 %b, %a		; <i32> [#uses=2]
> 	alloca i32		; <i32*>:0 [#uses=2]
> 	store i32 %tmp3, i32* %0, align 4
> 	bitcast i32* %0 to i8*		; <i8*>:1 [#uses=1]
> 	tail call void @writeToFile( i8* %1 )
> 	ret i32 %tmp3
> }
>
> define void @writeToFile(i8* %str) {
> entry:
> 	%tmp = tail call %struct.FILE* @fopen( i8* getelementptr ([8 x i8]*  
> @.str, i32 0, i32 0), i8* getelementptr ([2 x i8]* @.str1, i32 0,  
> i32 0) )		; <%struct.FILE*> [#uses=3]
> 	%tmp2 = icmp eq %struct.FILE* %tmp, null		; <i1> [#uses=1]
> 	br i1 %tmp2, label %bb, label %bb5
>
> bb:		; preds = %entry
> 	%tmp4 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([20 x  
> i8]* @.str2, i32 0, i32 0) )		; <i32> [#uses=0]
> 	ret void
>
> bb5:		; preds = %entry
> 	%tmp8 = tail call i32 (%struct.FILE*, i8*, ...)*  
> @fprintf( %struct.FILE* %tmp, i8* %str )		; <i32> [#uses=0]
> 	%tmp10 = tail call i32 @fclose( %struct.FILE* %tmp )		; <i32>  
> [#uses=0]
> 	ret void
> }
>
> declare %struct.FILE* @fopen(i8*, i8*)
>
> declare i32 @printf(i8*, ...)
>
> declare i32 @fprintf(%struct.FILE*, i8*, ...)
>
> declare i32 @fclose(%struct.FILE*)
>
> Thanks,
> Bhavani
>
>
>
>
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