[DAGCombiner] Remove explicit call to AddToWorklist in sqrt and reciprocal computations

Summary: These nodes end up being processed regardless due to DAGCombiner ensuring arguments are processed. This changes the order in which nodes are processed, which fixes an issue on PowerPC.

Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri, mcberg2017, stefanp, hfinkel

Subscribers: nemanjai, MaskRay, jsji, steven.zhang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66548

llvm-svn: 369662

2 files changed, 10 insertions, 56 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 30336353189..081544818f6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -20084,16 +20084,9 @@ SDValue DAGCombiner::BuildReciprocalEstimate(SDValue Op, SDNodeFlags Flags) {
       // Newton iterations: Est = Est + Est (1 - Arg * Est)
       for (int i = 0; i < Iterations; ++i) {
         SDValue NewEst = DAG.getNode(ISD::FMUL, DL, VT, Op, Est, Flags);
-        AddToWorklist(NewEst.getNode());
-
         NewEst = DAG.getNode(ISD::FSUB, DL, VT, FPOne, NewEst, Flags);
-        AddToWorklist(NewEst.getNode());
-
         NewEst = DAG.getNode(ISD::FMUL, DL, VT, Est, NewEst, Flags);
-        AddToWorklist(NewEst.getNode());
-
         Est = DAG.getNode(ISD::FADD, DL, VT, Est, NewEst, Flags);
-        AddToWorklist(Est.getNode());
       }
     }
     return Est;
@@ -20118,31 +20111,19 @@ SDValue DAGCombiner::buildSqrtNROneConst(SDValue Arg, SDValue Est,
   // We now need 0.5 * Arg which we can write as (1.5 * Arg - Arg) so that
   // this entire sequence requires only one FP constant.
   SDValue HalfArg = DAG.getNode(ISD::FMUL, DL, VT, ThreeHalves, Arg, Flags);
-  AddToWorklist(HalfArg.getNode());
-
   HalfArg = DAG.getNode(ISD::FSUB, DL, VT, HalfArg, Arg, Flags);
-  AddToWorklist(HalfArg.getNode());
 
   // Newton iterations: Est = Est * (1.5 - HalfArg * Est * Est)
   for (unsigned i = 0; i < Iterations; ++i) {
     SDValue NewEst = DAG.getNode(ISD::FMUL, DL, VT, Est, Est, Flags);
-    AddToWorklist(NewEst.getNode());
-
     NewEst = DAG.getNode(ISD::FMUL, DL, VT, HalfArg, NewEst, Flags);
-    AddToWorklist(NewEst.getNode());
-
     NewEst = DAG.getNode(ISD::FSUB, DL, VT, ThreeHalves, NewEst, Flags);
-    AddToWorklist(NewEst.getNode());
-
     Est = DAG.getNode(ISD::FMUL, DL, VT, Est, NewEst, Flags);
-    AddToWorklist(Est.getNode());
   }
 
   // If non-reciprocal square root is requested, multiply the result by Arg.
-  if (!Reciprocal) {
+  if (!Reciprocal)
     Est = DAG.getNode(ISD::FMUL, DL, VT, Est, Arg, Flags);
-    AddToWorklist(Est.getNode());
-  }
 
   return Est;
 }
@@ -20168,13 +20149,8 @@ SDValue DAGCombiner::buildSqrtNRTwoConst(SDValue Arg, SDValue Est,
   // E = (E * -0.5) * ((A * E) * E + -3.0)
   for (unsigned i = 0; i < Iterations; ++i) {
     SDValue AE = DAG.getNode(ISD::FMUL, DL, VT, Arg, Est, Flags);
-    AddToWorklist(AE.getNode());
-
     SDValue AEE = DAG.getNode(ISD::FMUL, DL, VT, AE, Est, Flags);
-    AddToWorklist(AEE.getNode());
-
     SDValue RHS = DAG.getNode(ISD::FADD, DL, VT, AEE, MinusThree, Flags);
-    AddToWorklist(RHS.getNode());
 
     // When calculating a square root at the last iteration build:
     // S = ((A * E) * -0.5) * ((A * E) * E + -3.0)
@@ -20187,10 +20163,8 @@ SDValue DAGCombiner::buildSqrtNRTwoConst(SDValue Arg, SDValue Est,
       // SQRT: LHS = (A * E) * -0.5
       LHS = DAG.getNode(ISD::FMUL, DL, VT, AE, MinusHalf, Flags);
     }
-    AddToWorklist(LHS.getNode());
 
     Est = DAG.getNode(ISD::FMUL, DL, VT, LHS, RHS, Flags);
-    AddToWorklist(Est.getNode());
   }
 
   return Est;
@@ -20247,16 +20221,11 @@ SDValue DAGCombiner::buildSqrtEstimateImpl(SDValue Op, SDNodeFlags Flags,
           SDValue Fabs = DAG.getNode(ISD::FABS, DL, VT, Op);
           SDValue IsDenorm = DAG.getSetCC(DL, CCVT, Fabs, NormC, ISD::SETLT);
           Est = DAG.getNode(SelOpcode, DL, VT, IsDenorm, FPZero, Est);
-          AddToWorklist(Fabs.getNode());
-          AddToWorklist(IsDenorm.getNode());
-          AddToWorklist(Est.getNode());
         } else {
           // X == 0.0 ? 0.0 : Est
           SDValue FPZero = DAG.getConstantFP(0.0, DL, VT);
           SDValue IsZero = DAG.getSetCC(DL, CCVT, Op, FPZero, ISD::SETEQ);
           Est = DAG.getNode(SelOpcode, DL, VT, IsZero, FPZero, Est);
-          AddToWorklist(IsZero.getNode());
-          AddToWorklist(Est.getNode());
         }
       }
     }
diff --git a/llvm/test/CodeGen/PowerPC/qpx-recipest.ll b/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
index 6c57aef370b..f841cb1c14c 100644
--- a/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
+++ b/llvm/test/CodeGen/PowerPC/qpx-recipest.ll
@@ -57,8 +57,6 @@ entry:
   ret <4 x double> %r
 }
 
-; FIXME: We're currently loading two constants here (1.5 and -1.5), and using
-;        an qvfmadd instead of a qvfnmsubs
 define <4 x double> @foof_fmf(<4 x double> %a, <4 x float> %b) nounwind {
 ; CHECK-LABEL: foof_fmf:
 ; CHECK:       # %bb.0: # %entry
@@ -66,12 +64,9 @@ define <4 x double> @foof_fmf(<4 x double> %a, <4 x float> %b) nounwind {
 ; CHECK-NEXT:    qvfrsqrtes 3, 2
 ; CHECK-NEXT:    addi 3, 3, .LCPI2_0@toc@l
 ; CHECK-NEXT:    qvlfsx 0, 0, 3
-; CHECK-NEXT:    addis 3, 2, .LCPI2_1@toc@ha
-; CHECK-NEXT:    addi 3, 3, .LCPI2_1@toc@l
-; CHECK-NEXT:    qvlfsx 4, 0, 3
-; CHECK-NEXT:    qvfmadds 0, 2, 0, 2
-; CHECK-NEXT:    qvfmuls 2, 3, 3
-; CHECK-NEXT:    qvfmadds 0, 0, 2, 4
+; CHECK-NEXT:    qvfmuls 4, 3, 3
+; CHECK-NEXT:    qvfnmsubs 2, 2, 0, 2
+; CHECK-NEXT:    qvfmadds 0, 2, 4, 0
 ; CHECK-NEXT:    qvfmuls 0, 3, 0
 ; CHECK-NEXT:    qvfmul 1, 1, 0
 ; CHECK-NEXT:    blr
@@ -179,8 +174,6 @@ entry:
   ret <4 x float> %r
 }
 
-; FIXME: We're currently loading two constants here (1.5 and -1.5), and using
-;        an qvfmadd instead of a qvfnmsubs
 define <4 x float> @goo_fmf(<4 x float> %a, <4 x float> %b) nounwind {
 ; CHECK-LABEL: goo_fmf:
 ; CHECK:       # %bb.0: # %entry
@@ -188,12 +181,9 @@ define <4 x float> @goo_fmf(<4 x float> %a, <4 x float> %b) nounwind {
 ; CHECK-NEXT:    qvfrsqrtes 3, 2
 ; CHECK-NEXT:    addi 3, 3, .LCPI6_0@toc@l
 ; CHECK-NEXT:    qvlfsx 0, 0, 3
-; CHECK-NEXT:    addis 3, 2, .LCPI6_1@toc@ha
-; CHECK-NEXT:    addi 3, 3, .LCPI6_1@toc@l
-; CHECK-NEXT:    qvlfsx 4, 0, 3
-; CHECK-NEXT:    qvfmadds 0, 2, 0, 2
-; CHECK-NEXT:    qvfmuls 2, 3, 3
-; CHECK-NEXT:    qvfmadds 0, 0, 2, 4
+; CHECK-NEXT:    qvfmuls 4, 3, 3
+; CHECK-NEXT:    qvfnmsubs 2, 2, 0, 2
+; CHECK-NEXT:    qvfmadds 0, 2, 4, 0
 ; CHECK-NEXT:    qvfmuls 0, 3, 0
 ; CHECK-NEXT:    qvfmuls 1, 1, 0
 ; CHECK-NEXT:    blr
@@ -360,8 +350,6 @@ entry:
   ret <4 x double> %r
 }
 
-; FIXME: We're currently loading two constants here (1.5 and -1.5), and using
-;        an qvfmadds instead of a qvfnmsubs
 define <4 x float> @goo3_fmf(<4 x float> %a) nounwind {
 ; CHECK-LABEL: goo3_fmf:
 ; CHECK:       # %bb.0: # %entry
@@ -369,14 +357,11 @@ define <4 x float> @goo3_fmf(<4 x float> %a) nounwind {
 ; CHECK-NEXT:    qvfrsqrtes 2, 1
 ; CHECK-NEXT:    addi 3, 3, .LCPI14_1@toc@l
 ; CHECK-NEXT:    qvlfsx 0, 0, 3
-; CHECK-NEXT:    addis 3, 2, .LCPI14_2@toc@ha
-; CHECK-NEXT:    addi 3, 3, .LCPI14_2@toc@l
-; CHECK-NEXT:    qvlfsx 3, 0, 3
 ; CHECK-NEXT:    addis 3, 2, .LCPI14_0@toc@ha
-; CHECK-NEXT:    qvfmuls 4, 2, 2
 ; CHECK-NEXT:    addi 3, 3, .LCPI14_0@toc@l
-; CHECK-NEXT:    qvfmadds 0, 1, 0, 1
-; CHECK-NEXT:    qvfmadds 0, 0, 4, 3
+; CHECK-NEXT:    qvfmuls 4, 2, 2
+; CHECK-NEXT:    qvfnmsubs 3, 1, 0, 1
+; CHECK-NEXT:    qvfmadds 0, 3, 4, 0
 ; CHECK-NEXT:    qvlfsx 3, 0, 3
 ; CHECK-NEXT:    qvfmuls 0, 2, 0
 ; CHECK-NEXT:    qvfmuls 0, 0, 1