llvm-6502/test/CodeGen/X86/lower-bitcast-v2i32.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

81 lines
1.9 KiB
LLVM

; RUN: llc < %s -march=x86-64 -mcpu=core2 -mattr=+sse2 | FileCheck %s
define double @test1(double %A) {
%1 = bitcast double %A to <2 x i32>
%add = add <2 x i32> %1, <i32 3, i32 5>
%2 = bitcast <2 x i32> %add to double
ret double %2
}
; FIXME: Ideally we should be able to fold the entire body of @test1 into a
; single paddd instruction. At the moment we produce the sequence
; pshufd+paddq+pshufd.
; CHECK-LABEL: test1
; CHECK-NOT: movsd
; CHECK: pshufd
; CHECK-NEXT: paddq
; CHECK-NEXT: pshufd
; CHECK-NEXT: ret
define double @test2(double %A, double %B) {
%1 = bitcast double %A to <2 x i32>
%2 = bitcast double %B to <2 x i32>
%add = add <2 x i32> %1, %2
%3 = bitcast <2 x i32> %add to double
ret double %3
}
; FIXME: Ideally we should be able to fold the entire body of @test2 into a
; single 'paddd %xmm1, %xmm0' instruction. At the moment we produce the
; sequence pshufd+pshufd+paddq+pshufd.
; CHECK-LABEL: test2
; CHECK-NOT: movsd
; CHECK: pshufd
; CHECK-NEXT: pshufd
; CHECK-NEXT: paddq
; CHECK-NEXT: pshufd
; CHECK-NEXT: ret
define i64 @test3(i64 %A) {
%1 = bitcast i64 %A to <2 x float>
%add = fadd <2 x float> %1, <float 3.0, float 5.0>
%2 = bitcast <2 x float> %add to i64
ret i64 %2
}
; CHECK-LABEL: test3
; CHECK-NOT: pshufd
; CHECK: addps
; CHECK-NOT: pshufd
; CHECK: ret
define i64 @test4(i64 %A) {
%1 = bitcast i64 %A to <2 x i32>
%add = add <2 x i32> %1, <i32 3, i32 5>
%2 = bitcast <2 x i32> %add to i64
ret i64 %2
}
; FIXME: At the moment we still produce the sequence pshufd+paddq+pshufd.
; Ideally, we should fold that sequence into a single paddd.
; CHECK-LABEL: test4
; CHECK: pshufd
; CHECK-NEXT: paddq
; CHECK-NEXT: pshufd
; CHECK: ret
define double @test5(double %A) {
%1 = bitcast double %A to <2 x float>
%add = fadd <2 x float> %1, <float 3.0, float 5.0>
%2 = bitcast <2 x float> %add to double
ret double %2
}
; CHECK-LABEL: test5
; CHECK: addps
; CHECK-NEXT: ret