[DAGCombine] Fold the (fma -x, y, -z) to -(fma x, y, z)

This is a positive combination as long as the NEG is NOT free,
as we are reducing the number of NEG from two to one.

Differential Revision: https://reviews.llvm.org/D72312

6 files changed, 37 insertions, 37 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cfc4671..37b1b17 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12639,6 +12639,15 @@ SDValue DAGCombiner::visitFMA(SDNode *N) {
     }
   }
 
+  // fold ((fma (fneg X), Y, (fneg Z)) -> fneg (fma X, Y, Z))
+  // fold ((fma X, (fneg Y), (fneg Z)) -> fneg (fma X, Y, Z))
+  if (!TLI.isFNegFree(VT) &&
+      TLI.isNegatibleForFree(SDValue(N, 0), DAG, LegalOperations,
+                             ForCodeSize) == 2)
+    return DAG.getNode(ISD::FNEG, DL, VT,
+                       TLI.getNegatedExpression(SDValue(N, 0), DAG,
+                                                LegalOperations, ForCodeSize),
+                       Flags);
   return SDValue();
 }
 
diff --git a/llvm/test/CodeGen/PowerPC/combine-fneg.ll b/llvm/test/CodeGen/PowerPC/combine-fneg.ll
index 1d85f4f..14bace2 100644
--- a/llvm/test/CodeGen/PowerPC/combine-fneg.ll
+++ b/llvm/test/CodeGen/PowerPC/combine-fneg.ll
@@ -5,19 +5,16 @@
 define <4 x double> @fneg_fdiv_splat(double %a0, <4 x double> %a1) {
 ; CHECK-LABEL: fneg_fdiv_splat:
 ; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addis 3, 2, .LCPI0_0@toc@ha
 ; CHECK-NEXT:    # kill: def $f1 killed $f1 def $vsl1
 ; CHECK-NEXT:    xxspltd 0, 1, 0
-; CHECK-NEXT:    addis 3, 2, .LCPI0_0@toc@ha
 ; CHECK-NEXT:    addi 3, 3, .LCPI0_0@toc@l
 ; CHECK-NEXT:    lxvd2x 1, 0, 3
-; CHECK-NEXT:    addis 3, 2, .LCPI0_1@toc@ha
 ; CHECK-NEXT:    xvredp 2, 0
-; CHECK-NEXT:    addi 3, 3, .LCPI0_1@toc@l
-; CHECK-NEXT:    xxswapd 1, 1
-; CHECK-NEXT:    xvnmsubadp 1, 0, 2
-; CHECK-NEXT:    xvmaddadp 2, 2, 1
-; CHECK-NEXT:    lxvd2x 1, 0, 3
 ; CHECK-NEXT:    xxswapd 1, 1
+; CHECK-NEXT:    xxlor 3, 1, 1
+; CHECK-NEXT:    xvmaddadp 3, 0, 2
+; CHECK-NEXT:    xvnmsubadp 2, 2, 3
 ; CHECK-NEXT:    xvmaddadp 1, 0, 2
 ; CHECK-NEXT:    xvmsubadp 2, 2, 1
 ; CHECK-NEXT:    xvmuldp 34, 34, 2
diff --git a/llvm/test/CodeGen/PowerPC/fma-combine.ll b/llvm/test/CodeGen/PowerPC/fma-combine.ll
index 5baf663..88da295 100644
--- a/llvm/test/CodeGen/PowerPC/fma-combine.ll
+++ b/llvm/test/CodeGen/PowerPC/fma-combine.ll
@@ -8,14 +8,12 @@
 define double @fma_combine1(double %a, double %b, double %c) {
 ; CHECK-FAST-LABEL: fma_combine1:
 ; CHECK-FAST:       # %bb.0: # %entry
-; CHECK-FAST-NEXT:    xsnegdp 0, 3
-; CHECK-FAST-NEXT:    xsmsubadp 1, 0, 2
+; CHECK-FAST-NEXT:    xsnmaddadp 1, 3, 2
 ; CHECK-FAST-NEXT:    blr
 ;
 ; CHECK-FAST-NOVSX-LABEL: fma_combine1:
 ; CHECK-FAST-NOVSX:       # %bb.0: # %entry
-; CHECK-FAST-NOVSX-NEXT:    fneg 0, 3
-; CHECK-FAST-NOVSX-NEXT:    fmsub 1, 0, 2, 1
+; CHECK-FAST-NOVSX-NEXT:    fnmadd 1, 3, 2, 1
 ; CHECK-FAST-NOVSX-NEXT:    blr
 ;
 ; CHECK-LABEL: fma_combine1:
@@ -34,14 +32,12 @@ entry:
 define double @fma_combine2(double %a, double %b, double %c) {
 ; CHECK-FAST-LABEL: fma_combine2:
 ; CHECK-FAST:       # %bb.0: # %entry
-; CHECK-FAST-NEXT:    xsnegdp 0, 3
-; CHECK-FAST-NEXT:    xsmsubadp 1, 2, 0
+; CHECK-FAST-NEXT:    xsnmaddadp 1, 2, 3
 ; CHECK-FAST-NEXT:    blr
 ;
 ; CHECK-FAST-NOVSX-LABEL: fma_combine2:
 ; CHECK-FAST-NOVSX:       # %bb.0: # %entry
-; CHECK-FAST-NOVSX-NEXT:    fneg 0, 3
-; CHECK-FAST-NOVSX-NEXT:    fmsub 1, 2, 0, 1
+; CHECK-FAST-NOVSX-NEXT:    fnmadd 1, 2, 3, 1
 ; CHECK-FAST-NOVSX-NEXT:    blr
 ;
 ; CHECK-LABEL: fma_combine2:
@@ -62,25 +58,25 @@ entry:
 define double @fma_combine_two_uses(double %a, double %b, double %c) {
 ; CHECK-FAST-LABEL: fma_combine_two_uses:
 ; CHECK-FAST:       # %bb.0: # %entry
-; CHECK-FAST-NEXT:    xsnegdp 0, 3
+; CHECK-FAST-NEXT:    xsnegdp 0, 1
 ; CHECK-FAST-NEXT:    addis 3, 2, v@toc@ha
 ; CHECK-FAST-NEXT:    addis 4, 2, z@toc@ha
-; CHECK-FAST-NEXT:    xsnegdp 3, 1
-; CHECK-FAST-NEXT:    xsmsubadp 1, 0, 2
-; CHECK-FAST-NEXT:    stfd 0, z@toc@l(4)
-; CHECK-FAST-NEXT:    stfd 3, v@toc@l(3)
+; CHECK-FAST-NEXT:    xsnmaddadp 1, 3, 2
+; CHECK-FAST-NEXT:    xsnegdp 2, 3
+; CHECK-FAST-NEXT:    stfd 0, v@toc@l(3)
+; CHECK-FAST-NEXT:    stfd 2, z@toc@l(4)
 ; CHECK-FAST-NEXT:    blr
 ;
 ; CHECK-FAST-NOVSX-LABEL: fma_combine_two_uses:
 ; CHECK-FAST-NOVSX:       # %bb.0: # %entry
-; CHECK-FAST-NOVSX-NEXT:    fneg 3, 3
+; CHECK-FAST-NOVSX-NEXT:    fnmadd 0, 3, 2, 1
+; CHECK-FAST-NOVSX-NEXT:    fneg 2, 1
 ; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, v@toc@ha
 ; CHECK-FAST-NOVSX-NEXT:    addis 4, 2, z@toc@ha
-; CHECK-FAST-NOVSX-NEXT:    fmsub 0, 3, 2, 1
-; CHECK-FAST-NOVSX-NEXT:    fneg 2, 1
-; CHECK-FAST-NOVSX-NEXT:    stfd 3, z@toc@l(4)
+; CHECK-FAST-NOVSX-NEXT:    fneg 3, 3
 ; CHECK-FAST-NOVSX-NEXT:    fmr 1, 0
 ; CHECK-FAST-NOVSX-NEXT:    stfd 2, v@toc@l(3)
+; CHECK-FAST-NOVSX-NEXT:    stfd 3, z@toc@l(4)
 ; CHECK-FAST-NOVSX-NEXT:    blr
 ;
 ; CHECK-LABEL: fma_combine_two_uses:
@@ -108,19 +104,17 @@ entry:
 define double @fma_combine_one_use(double %a, double %b, double %c) {
 ; CHECK-FAST-LABEL: fma_combine_one_use:
 ; CHECK-FAST:       # %bb.0: # %entry
-; CHECK-FAST-NEXT:    xsnegdp 0, 3
+; CHECK-FAST-NEXT:    xsnegdp 0, 1
 ; CHECK-FAST-NEXT:    addis 3, 2, v@toc@ha
-; CHECK-FAST-NEXT:    xsnegdp 3, 1
-; CHECK-FAST-NEXT:    xsmsubadp 1, 0, 2
-; CHECK-FAST-NEXT:    stfd 3, v@toc@l(3)
+; CHECK-FAST-NEXT:    xsnmaddadp 1, 3, 2
+; CHECK-FAST-NEXT:    stfd 0, v@toc@l(3)
 ; CHECK-FAST-NEXT:    blr
 ;
 ; CHECK-FAST-NOVSX-LABEL: fma_combine_one_use:
 ; CHECK-FAST-NOVSX:       # %bb.0: # %entry
-; CHECK-FAST-NOVSX-NEXT:    fneg 0, 3
-; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, v@toc@ha
-; CHECK-FAST-NOVSX-NEXT:    fmsub 0, 0, 2, 1
+; CHECK-FAST-NOVSX-NEXT:    fnmadd 0, 3, 2, 1
 ; CHECK-FAST-NOVSX-NEXT:    fneg 2, 1
+; CHECK-FAST-NOVSX-NEXT:    addis 3, 2, v@toc@ha
 ; CHECK-FAST-NOVSX-NEXT:    fmr 1, 0
 ; CHECK-FAST-NOVSX-NEXT:    stfd 2, v@toc@l(3)
 ; CHECK-FAST-NOVSX-NEXT:    blr
diff --git a/llvm/test/CodeGen/PowerPC/qpx-recipest.ll b/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
index 3bfd92a..246bec1 100644
--- a/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
+++ b/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
@@ -229,8 +229,8 @@ define <4 x double> @foo2_fmf(<4 x double> %a, <4 x double> %b) nounwind {
 ; CHECK-NEXT:    qvfre 3, 2
 ; CHECK-NEXT:    addi 3, 3, .LCPI8_0@toc@l
 ; CHECK-NEXT:    qvlfdx 0, 0, 3
-; CHECK-NEXT:    qvfnmsub 0, 2, 3, 0
-; CHECK-NEXT:    qvfmadd 0, 3, 0, 3
+; CHECK-NEXT:    qvfmadd 0, 2, 3, 0
+; CHECK-NEXT:    qvfnmsub 0, 3, 0, 3
 ; CHECK-NEXT:    qvfmul 3, 1, 0
 ; CHECK-NEXT:    qvfnmsub 1, 2, 3, 1
 ; CHECK-NEXT:    qvfmadd 1, 0, 1, 3
diff --git a/llvm/test/CodeGen/PowerPC/recipest.ll b/llvm/test/CodeGen/PowerPC/recipest.ll
index bc33617..a0afb4b 100644
--- a/llvm/test/CodeGen/PowerPC/recipest.ll
+++ b/llvm/test/CodeGen/PowerPC/recipest.ll
@@ -194,8 +194,8 @@ define <4 x float> @hoo_safe(<4 x float> %a, <4 x float> %b) nounwind {
 define double @foo2_fmf(double %a, double %b) nounwind {
 ; CHECK: @foo2_fmf
 ; CHECK-DAG: fre
-; CHECK-DAG: fnmsub
-; CHECK: fmadd
+; CHECK-DAG: fmadd
+; CHECK: fnmsub
 ; CHECK-NEXT: fmul
 ; CHECK-NEXT: fnmsub
 ; CHECK-NEXT: fmadd
diff --git a/llvm/test/CodeGen/PowerPC/repeated-fp-divisors.ll b/llvm/test/CodeGen/PowerPC/repeated-fp-divisors.ll
index 9ab320c..2cdf832 100644
--- a/llvm/test/CodeGen/PowerPC/repeated-fp-divisors.ll
+++ b/llvm/test/CodeGen/PowerPC/repeated-fp-divisors.ll
@@ -13,9 +13,9 @@ define <4 x float> @repeated_fp_divisor(float %a, <4 x float> %b) {
 ; CHECK-NEXT:    lvx 4, 0, 3
 ; CHECK-NEXT:    xxspltw 0, 0, 0
 ; CHECK-NEXT:    xvresp 1, 0
-; CHECK-NEXT:    xvnmsubasp 35, 0, 1
+; CHECK-NEXT:    xvmaddasp 35, 0, 1
 ; CHECK-NEXT:    xvmulsp 0, 34, 36
-; CHECK-NEXT:    xvmaddasp 1, 1, 35
+; CHECK-NEXT:    xvnmsubasp 1, 1, 35
 ; CHECK-NEXT:    xvmulsp 34, 0, 1
 ; CHECK-NEXT:    blr
   %ins = insertelement <4 x float> undef, float %a, i32 0