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[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
This commit is contained in:
Amaury Sechet 2019-08-22 15:35:45 +00:00
parent c9649eb9da
commit 95cf66de7c
2 changed files with 10 additions and 56 deletions
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33
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -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());
}
}
}

33
llvm/test/CodeGen/PowerPC/qpx-recipest.ll
View File

@ -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