Split the estimate() interface into separate functions for each type. NFC.
It was hacky to use an opcode as a switch because it won't always match
(rsqrte != sqrte), and it looks like we'll need to add more special casing
per arch than I had hoped for. Eg, x86 will prefer a different NR estimate
implementation. ARM will want to use it's 'step' instructions. There also
don't appear to be any new estimate instructions in any arch in a long,
long time. Altivec vloge and vexpte may have been the first and last in
that field...
llvm-svn: 218698
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 5750e2f..e0396fd 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -7458,25 +7458,14 @@
// Target Optimization Hooks
//===----------------------------------------------------------------------===//
-SDValue PPCTargetLowering::getEstimate(unsigned Opcode, SDValue Operand,
- DAGCombinerInfo &DCI,
- unsigned &RefinementSteps) const {
+SDValue PPCTargetLowering::getRsqrtEstimate(SDValue Operand,
+ DAGCombinerInfo &DCI,
+ unsigned &RefinementSteps) const {
EVT VT = Operand.getValueType();
- SDValue RV;
- if (Opcode == ISD::FSQRT) {
- if ((VT == MVT::f32 && Subtarget.hasFRSQRTES()) ||
- (VT == MVT::f64 && Subtarget.hasFRSQRTE()) ||
- (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
- (VT == MVT::v2f64 && Subtarget.hasVSX()))
- RV = DCI.DAG.getNode(PPCISD::FRSQRTE, SDLoc(Operand), VT, Operand);
- } else if (Opcode == ISD::FDIV) {
- if ((VT == MVT::f32 && Subtarget.hasFRES()) ||
- (VT == MVT::f64 && Subtarget.hasFRE()) ||
- (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
- (VT == MVT::v2f64 && Subtarget.hasVSX()))
- RV = DCI.DAG.getNode(PPCISD::FRE, SDLoc(Operand), VT, Operand);
- }
- if (RV.getNode()) {
+ if ((VT == MVT::f32 && Subtarget.hasFRSQRTES()) ||
+ (VT == MVT::f64 && Subtarget.hasFRSQRTE()) ||
+ (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
+ (VT == MVT::v2f64 && Subtarget.hasVSX())) {
// Convergence is quadratic, so we essentially double the number of digits
// correct after every iteration. For both FRE and FRSQRTE, the minimum
// architected relative accuracy is 2^-5. When hasRecipPrec(), this is
@@ -7484,8 +7473,29 @@
RefinementSteps = Subtarget.hasRecipPrec() ? 1 : 3;
if (VT.getScalarType() == MVT::f64)
++RefinementSteps;
+ return DCI.DAG.getNode(PPCISD::FRSQRTE, SDLoc(Operand), VT, Operand);
}
- return RV;
+ return SDValue();
+}
+
+SDValue PPCTargetLowering::getRecipEstimate(SDValue Operand,
+ DAGCombinerInfo &DCI,
+ unsigned &RefinementSteps) const {
+ EVT VT = Operand.getValueType();
+ if ((VT == MVT::f32 && Subtarget.hasFRES()) ||
+ (VT == MVT::f64 && Subtarget.hasFRE()) ||
+ (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
+ (VT == MVT::v2f64 && Subtarget.hasVSX())) {
+ // Convergence is quadratic, so we essentially double the number of digits
+ // correct after every iteration. For both FRE and FRSQRTE, the minimum
+ // architected relative accuracy is 2^-5. When hasRecipPrec(), this is
+ // 2^-14. IEEE float has 23 digits and double has 52 digits.
+ RefinementSteps = Subtarget.hasRecipPrec() ? 1 : 3;
+ if (VT.getScalarType() == MVT::f64)
+ ++RefinementSteps;
+ return DCI.DAG.getNode(PPCISD::FRE, SDLoc(Operand), VT, Operand);
+ }
+ return SDValue();
}
static bool isConsecutiveLSLoc(SDValue Loc, EVT VT, LSBaseSDNode *Base,