[DAGCombine] Fold setcc_eq infinity into is.fpclass (#67829)

Author: ecnelises

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -5104,6 +5104,21 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
       }
     }
 
+    // setueq/setoeq X, (fabs Inf) -> is_fpclass X, fcInf
+    if (isOperationLegalOrCustom(ISD::IS_FPCLASS, N0.getValueType()) &&
+        !isFPImmLegal(CFP->getValueAPF(), CFP->getValueType(0))) {
+      bool IsFabs = N0.getOpcode() == ISD::FABS;
+      SDValue Op = IsFabs ? N0.getOperand(0) : N0;
+      if ((Cond == ISD::SETOEQ || Cond == ISD::SETUEQ) && CFP->isInfinity()) {
+        FPClassTest Flag = CFP->isNegative() ? (IsFabs ? fcNone : fcNegInf)
+                                             : (IsFabs ? fcInf : fcPosInf);
+        if (Cond == ISD::SETUEQ)
+          Flag |= fcNan;
+        return DAG.getNode(ISD::IS_FPCLASS, dl, VT, Op,
+                           DAG.getTargetConstant(Flag, dl, MVT::i32));
+      }
+    }
+
     // If the condition is not legal, see if we can find an equivalent one
     // which is legal.
     if (!isCondCodeLegal(Cond, N0.getSimpleValueType())) {

llvm/test/CodeGen/PowerPC/fp-classify.ll

@@ -18,12 +18,9 @@ define zeroext i1 @abs_isinff(float %x) {
 ;
 ; P9-LABEL: abs_isinff:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI0_0@toc@ha
-; P9-NEXT:    xsabsdp 0, 1
-; P9-NEXT:    li 4, 1
-; P9-NEXT:    lfs 1, .LCPI0_0@toc@l(3)
+; P9-NEXT:    xststdcsp 0, 1, 48
 ; P9-NEXT:    li 3, 0
-; P9-NEXT:    fcmpu 0, 0, 1
+; P9-NEXT:    li 4, 1
 ; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
@@ -46,12 +43,9 @@ define zeroext i1 @abs_isinf(double %x) {
 ;
 ; P9-LABEL: abs_isinf:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI1_0@toc@ha
-; P9-NEXT:    xsabsdp 0, 1
-; P9-NEXT:    li 4, 1
-; P9-NEXT:    lfs 1, .LCPI1_0@toc@l(3)
+; P9-NEXT:    xststdcdp 0, 1, 48
 ; P9-NEXT:    li 3, 0
-; P9-NEXT:    fcmpu 0, 0, 1
+; P9-NEXT:    li 4, 1
 ; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
@@ -91,13 +85,9 @@ define zeroext i1 @abs_isinfq(fp128 %x) {
 ;
 ; P9-LABEL: abs_isinfq:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI2_0@toc@ha
-; P9-NEXT:    xsabsqp 2, 2
-; P9-NEXT:    li 4, 1
-; P9-NEXT:    addi 3, 3, .LCPI2_0@toc@l
-; P9-NEXT:    lxv 35, 0(3)
+; P9-NEXT:    xststdcqp 0, 2, 48
 ; P9-NEXT:    li 3, 0
-; P9-NEXT:    xscmpuqp 0, 2, 3
+; P9-NEXT:    li 4, 1
 ; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
@@ -119,12 +109,10 @@ define zeroext i1 @abs_isinfornanf(float %x) {
 ;
 ; P9-LABEL: abs_isinfornanf:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI3_0@toc@ha
-; P9-NEXT:    xsabsdp 0, 1
-; P9-NEXT:    lfs 1, .LCPI3_0@toc@l(3)
-; P9-NEXT:    li 3, 1
-; P9-NEXT:    fcmpu 0, 0, 1
-; P9-NEXT:    isellt 3, 0, 3
+; P9-NEXT:    xststdcsp 0, 1, 112
+; P9-NEXT:    li 3, 0
+; P9-NEXT:    li 4, 1
+; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
   %0 = tail call float @llvm.fabs.f32(float %x)
@@ -145,12 +133,10 @@ define zeroext i1 @abs_isinfornan(double %x) {
 ;
 ; P9-LABEL: abs_isinfornan:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI4_0@toc@ha
-; P9-NEXT:    xsabsdp 0, 1
-; P9-NEXT:    lfs 1, .LCPI4_0@toc@l(3)
-; P9-NEXT:    li 3, 1
-; P9-NEXT:    fcmpu 0, 0, 1
-; P9-NEXT:    isellt 3, 0, 3
+; P9-NEXT:    xststdcdp 0, 1, 112
+; P9-NEXT:    li 3, 0
+; P9-NEXT:    li 4, 1
+; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
   %0 = tail call double @llvm.fabs.f64(double %x)
@@ -212,13 +198,10 @@ define zeroext i1 @abs_isinfornanq(fp128 %x) {
 ;
 ; P9-LABEL: abs_isinfornanq:
 ; P9:       # %bb.0: # %entry
-; P9-NEXT:    addis 3, 2, .LCPI5_0@toc@ha
-; P9-NEXT:    xsabsqp 2, 2
-; P9-NEXT:    addi 3, 3, .LCPI5_0@toc@l
-; P9-NEXT:    lxv 35, 0(3)
-; P9-NEXT:    li 3, 1
-; P9-NEXT:    xscmpuqp 0, 2, 3
-; P9-NEXT:    isellt 3, 0, 3
+; P9-NEXT:    xststdcqp 0, 2, 112
+; P9-NEXT:    li 3, 0
+; P9-NEXT:    li 4, 1
+; P9-NEXT:    iseleq 3, 4, 3
 ; P9-NEXT:    blr
 entry:
   %0 = tail call fp128 @llvm.fabs.f128(fp128 %x)

llvm/test/CodeGen/PowerPC/is_fpclass.ll

@@ -117,12 +117,9 @@ define i1 @isinf_float(float %x) nounwind {
 define i1 @isinf_ppc_fp128(ppc_fp128 %x) nounwind {
 ; CHECK-LABEL: isinf_ppc_fp128:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    addis 3, 2, .LCPI9_0@toc@ha
-; CHECK-NEXT:    xsabsdp 0, 1
-; CHECK-NEXT:    li 4, 1
-; CHECK-NEXT:    lfs 1, .LCPI9_0@toc@l(3)
+; CHECK-NEXT:    xststdcdp 0, 1, 48
 ; CHECK-NEXT:    li 3, 0
-; CHECK-NEXT:    fcmpu 0, 0, 1
+; CHECK-NEXT:    li 4, 1
 ; CHECK-NEXT:    iseleq 3, 4, 3
 ; CHECK-NEXT:    blr
   %1 = call i1 @llvm.is.fpclass.ppcf128(ppc_fp128 %x, i32 516)  ; 0x204 = "inf"