llvm-6502/test/CodeGen/X86/ret-mmx.ll
Andrea Di Biagio 8a712ba229 [X86] Improve the lowering of BITCAST dag nodes from type f64 to type v2i32 (and vice versa).
Before this patch, the backend always emitted a store+load sequence to
bitconvert from f64 to i64 the input operand of a ISD::BITCAST dag node that
performed a bitconvert from type MVT::f64 to type MVT::v2i32. The resulting
i64 node was then used to build a v2i32 vector.

With this patch, the backend now produces a cheaper SCALAR_TO_VECTOR from
MVT::f64 to MVT::v2f64. That SCALAR_TO_VECTOR is then followed by a "free"
bitcast to type MVT::v4i32. The elements of the resulting
v4i32 are then extracted to build a v2i32 vector (which is illegal and
therefore promoted to MVT::v2i64).

This is in general cheaper than emitting a stack store+load sequence
to bitconvert the operand from type f64 to type i64.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208107 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-06 17:09:03 +00:00

41 lines
855 B
LLVM

; RUN: llc < %s -mtriple=x86_64-apple-darwin11 -mcpu=core2 -mattr=+mmx,+sse2 | FileCheck %s
; rdar://6602459
@g_v1di = external global <1 x i64>
define void @t1() nounwind {
entry:
%call = call <1 x i64> @return_v1di() ; <<1 x i64>> [#uses=0]
store <1 x i64> %call, <1 x i64>* @g_v1di
ret void
; CHECK-LABEL: t1:
; CHECK: callq
; CHECK-NEXT: movq _g_v1di
; CHECK-NEXT: movq %rax,
}
declare <1 x i64> @return_v1di()
define <1 x i64> @t2() nounwind {
ret <1 x i64> <i64 1>
; CHECK-LABEL: t2:
; CHECK: movl $1
; CHECK-NEXT: ret
}
define <2 x i32> @t3() nounwind {
ret <2 x i32> <i32 1, i32 0>
; CHECK-LABEL: t3:
; CHECK: movl $1
; CHECK: movd {{.*}}, %xmm0
}
define double @t4() nounwind {
ret double bitcast (<2 x i32> <i32 1, i32 0> to double)
; CHECK-LABEL: t4:
; CHECK-NOT: movl $1
; CHECK-NOT: pshufd
; CHECK: movsd {{.*}}, %xmm0
}