[llvm-commits] [llvm] r160117 - in /llvm/trunk: include/llvm/IntrinsicsX86.td lib/Target/X86/X86ISelLowering.cpp lib/Target/X86/X86ISelLowering.h lib/Target/X86/X86InstrInfo.td test/CodeGen/X86/rdrand.ll

[Jakob Stoklund Olesen]

On Jul 12, 2012, at 2:31 AM, Benjamin Kramer <benny.kra at googlemail.com> wrote:

> Author: d0k
> Date: Thu Jul 12 04:31:43 2012
> New Revision: 160117
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=160117&view=rev
> Log:
> Add intrinsics for Ivy Bridge's rdrand instruction.
> 
> The rdrand/cmov sequence is the same that is emitted by both
> GCC and ICC.

Hi Ben,

You should make sure we don't CSE these instructions:

define i32 @f() nounwind {
entry:
  %0 = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
  %1 = extractvalue { i32, i32 } %0, 0
  %2 = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
  %3 = extractvalue { i32, i32 } %2, 0
  %add = add i32 %3, %1
  ret i32 %add
}

$ llc -mattr=+rdrand < rdrand.ll
f:                                      # @f
# BB#0:                                 # %entry
	rdrandl	%eax
	addl	%eax, %eax
	ret

/jakob