[llvm-dev] array fill idioms

[Bagel via llvm-dev]

Yes, I know this works peachy keen for char arrays.  I'm looking at (which is
hard to express in C) something like

void foo () {
   int bar[20] = { 42, 42, ..., 42 };
}

I don't want to do a memcopy of the 20 element constant array, and memset
doesn't work here.  I want an intrinsic that copys the scalar int constant 42
to each element of the int array.

bagel


On 11/10/2016 03:30 PM, Mehdi Amini wrote:
> Hi,
> 
> An alternative is to perform what is done for the equivalent C construct:
> 
> void foo() {
>   char bar[20] = “hello”;
> }
> 
> ->
> 
> @foo.bar = private unnamed_addr constant [20 x i8] c"hello\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 16
> define void @foo() #0 {
>   %1 = alloca [20 x i8], align 16
>   %2 = bitcast [20 x i8]* %1 to i8*
>   call void @llvm.memcpy.p0i8.p0i8.i64(i8* %2, i8* getelementptr inbounds ([20 x i8], [20 x i8]* @foo.bar, i32 0, i32 0), i64 20, i32 16, i1 false)
>   ret void
> }
> 
> 
> — 
> Mehdi