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Hi all,

Is it possible to use \_\_builtin\_assume (or something similar like \_\_builtin\_unreachable) to eliminate stores?

Eg I would expect that I if I write something as follows the optimizer could optimize away the store to the variable a:

void foo(int\* a)

{

\_\_builtin\_assume(\*a == 0);

\*a = 0;

}

But the generated code still writes to the variable:

; Function Attrs: nounwind uwtable

define void @\_Z3fooPi(i32\* nocapture %a) #0 {

%1 = load i32, i32\* %a, align 4, !tbaa !8

%2 = icmp eq i32 %1, 0

tail call void @llvm.assume(i1 %2)

store i32 0, i32\* %a, align 4, !tbaa !8

ret void

}

00000000000000a0 <\_Z3fooPi>:

a0: c7 07 00 00 00 00 movl $0x0,(%rdi)

a6: c3 retq

Why this store not optimized away?

Is there another way to tell the optimizer that the store can be eliminated?

Regards,

Tom