[LLVMdev] Call to non-constant memset() being generated where libc is not available

[Duncan Sands]

Hi David,

> I am compiling something without standard libraries, including no libc.

compile with -fno-builtin  That said, note that GCC for example requires memset
to be available even in a freestanding environment.

Ciao, Duncan.

>
> Somehow, this bitcode is being generated by plain array manipulation code:
>
>    %12 = add i8 %11, -19
>    %tmp35 = icmp sgt i32 %9, 1
>    %smax36 = select i1 %tmp35, i32 %9, i32 1
>    call void @llvm.memset.p0i8.i32(i8* getelementptr inbounds ([100 x i8]*
> @global_array_char, i32 0, i32 0), i8 %12, i32 %smax36, i32 1, i1 false)
>
> (global_array_char is an array of length 100, which only partially gets used.)
>
> This gets lowered by LLC to a library call to memset(), which cannot be satisfied.
>
> Any advice?
>
> Thanks,
> David Meyer
>
>
>
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