[LLVMdev] Another memory fun

[Zalunin Pavel]

hm.... I think, that is valid in c

but next code too doesn't works right:
; ModuleID = 'sample.lz'
@.str1 = internal global [6 x i8] c"world\00"           ; <[6 x i8]*>
[#uses=1]
@.str2 = internal global [7 x i8] c"hello \00"          ; <[7 x i8]*>
[#uses=1]
@.str7 = internal global [7 x i8] c"father\00"          ; <[7 x i8]*>
[#uses=1]
@.str8 = internal global [8 x i8] c"mother \00"         ; <[8 x i8]*>
[#uses=1]

declare i32 @puts(i8*)

declare i8* @strcat(i8*, i8*)

declare i32 @strlen(i8*)

declare void @llvm.memcpy.i32(i8*, i8*, i32, i32)

define i32 @main() {
mainBlock:
        %str3 = getelementptr [7 x i8]* @.str2, i64 0, i64 0            ;
<i8*> [#uses=2]
        %str4 = getelementptr [6 x i8]* @.str1, i64 0, i64 0            ;
<i8*> [#uses=1]
        call i8* @strcat( i8* %str3, i8* %str4 )                ; <i8*>:0
[#uses=0]
        %tmp6 = call i32 @puts( i8* %str3 )             ; <i32> [#uses=0]
        %str9 = getelementptr [8 x i8]* @.str8, i64 0, i64 0            ;
<i8*> [#uses=2]
        %str10 = getelementptr [7 x i8]* @.str7, i64 0, i64 0           ;
<i8*> [#uses=1]
        call i8* @strcat( i8* %str9, i8* %str10 )               ; <i8*>:1
[#uses=0]
        %tmp12 = call i32 @puts( i8* %str9 )            ; <i32> [#uses=0]
        ret i32 0
}


writes:
%
hello world
mother orld


I tried decompile code:
 main(int argc, char **argv) {
  char str1[] = "mother ";
  strcat(str1, "father");
  return 0;
}

decompiler gives to me code, in this code string " mother\0" presents as:

%str1 = alloca [8 x i8], align 16		; <[8 x i8]*> [#uses=9]
	%tmp1 = getelementptr [8 x i8]* %str1, i32 0, i32 0		; <i8*> [#uses=2]
	store i8 109, i8* %tmp1, align 16
	%tmp4 = getelementptr [8 x i8]* %str1, i32 0, i32 1		; <i8*> [#uses=1]
	store i8 111, i8* %tmp4, align 1
	%tmp7 = getelementptr [8 x i8]* %str1, i32 0, i32 2		; <i8*> [#uses=1]
	store i8 116, i8* %tmp7, align 1
	%tmp10 = getelementptr [8 x i8]* %str1, i32 0, i32 3		; <i8*> [#uses=1]
	store i8 104, i8* %tmp10, align 1
	%tmp13 = getelementptr [8 x i8]* %str1, i32 0, i32 4		; <i8*> [#uses=1]
	store i8 101, i8* %tmp13, align 1
	%tmp16 = getelementptr [8 x i8]* %str1, i32 0, i32 5		; <i8*> [#uses=1]
	store i8 114, i8* %tmp16, align 1
	%tmp19 = getelementptr [8 x i8]* %str1, i32 0, i32 6		; <i8*> [#uses=1]
	store i8 32, i8* %tmp19, align 1
	%tmp22 = getelementptr [8 x i8]* %str1, i32 0, i32 7		; <i8*> [#uses=1]

	store i8 0, i8* %tmp22, align 1


it's looks funny, can you say another less complex way to do this operation?
Thanks

Best regards,
    Zalunin Pavel
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