bitcast and bitwise operations on floating point numbers

There are some occasions where it is useful to perform bitwise AND/OR
on floating point numbers (e.g. when working with extended precision).

An easy way to do this is to bitcast to an unsigned integer, do your
operation, then bitcast back to a float, which will generate IR along
the lines of:

%1 = bitcast double %0 to i64
%2 = and i64 %1, -4294967296
%3 = bitcast i64 %2 to double
ret double %3

Is LLVM able translate this to use the relevant floating point
instructions when available (i.e. ANDPD/VANDPD on x86)?

(this originally came up on julia-dev:
https://groups.google.com/d/topic/julia-dev/5y1y6Uj8T1A/discussion)

Simon

Best way to find out is to run it. Looks like no, but maybe it would if
you played around with the triple.

$ cat t.ll
define double @foo(double %arg) {
  %1 = bitcast double %arg to i64
  %2 = and i64 %1, -4294967296
  %3 = bitcast i64 %2 to double
  ret double %3
}
$ opt -O3 < t.ll | llc -O3
  .section __TEXT,__text,regular,pure_instructions
  .macosx_version_min 14, 1
  .globl _foo
  .align 4, 0x90
_foo: ## @foo
## BB#0:
  movd %xmm0, %rax
  movabsq $-4294967296, %rcx ## imm = 0xFFFFFFFF00000000
  andq %rax, %rcx
  movd %rcx, %xmm0
  retq

.subsections_via_symbols