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llvm-mirror/test/CodeGen/PowerPC/fneg.ll
Sanjay Patel 7bb0bc7bff [DAGCombiner] cancel fnegs from multiplied operands of FMA
(-X) * (-Y) + Z --> X * Y + Z

This is a missing optimization that shows up as a potential regression in D66050,
so we should solve it first. We appear to be partly missing this fold in IR as well.

We do handle the simpler case already:
(-X) * (-Y) --> X * Y

And it might be beneficial to make the constraint less conservative (eg, if both
operands are cheap, but not necessarily cheaper), but that causes infinite looping
for the existing fmul transform.

Differential Revision: https://reviews.llvm.org/D66755

llvm-svn: 370071
2019-08-27 15:17:46 +00:00

42 lines
1.3 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -verify-machineinstrs < %s -mtriple=ppc32-- -ppc-asm-full-reg-names | FileCheck %s
define double @test1(double %a, double %b, double %c, double %d) {
; CHECK-LABEL: test1:
; CHECK: # %bb.0:
; CHECK-NEXT: fmul f0, f3, f4
; CHECK-NEXT: fmul f1, f1, f2
; CHECK-NEXT: fadd f1, f1, f0
; CHECK-NEXT: blr
%tmp2 = fsub double -0.000000e+00, %c
%tmp4 = fmul double %tmp2, %d
%tmp7 = fmul double %a, %b
%tmp9 = fsub double %tmp7, %tmp4
ret double %tmp9
}
declare float @llvm.fmuladd.f32(float, float, float) #4
define float @fma_fneg_fneg(float %x, float %y, float %z) {
; CHECK-LABEL: fma_fneg_fneg:
; CHECK: # %bb.0:
; CHECK-NEXT: fmadds f1, f1, f2, f3
; CHECK-NEXT: blr
%negx = fneg float %x
%negy = fneg float %y
%r = call float @llvm.fmuladd.f32(float %negx, float %negy, float %z)
ret float %r
}
define float @fma_fneg_fsub(float %x, float %y0, float %y1, float %z) {
; CHECK-LABEL: fma_fneg_fsub:
; CHECK: # %bb.0:
; CHECK-NEXT: fsubs f0, f3, f2
; CHECK-NEXT: fmadds f1, f1, f0, f4
; CHECK-NEXT: blr
%negx = fneg float %x
%negy = fsub nsz float %y0, %y1
%r = call float @llvm.fmuladd.f32(float %negx, float %negy, float %z)
ret float %r
}