[CodeGen] Fix ConvertNodeToLibcall for STRICT_FPOWI

Reviewed By: PengfeiWang

Differential Revision: https://reviews.llvm.org/D125159

Author: xiangzh1

llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

@@ -4098,12 +4098,25 @@ void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
     assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unexpected fpowi.");
     if (!TLI.getLibcallName(LC)) {
       // Some targets don't have a powi libcall; use pow instead.
-      SDValue Exponent = DAG.getNode(ISD::SINT_TO_FP, SDLoc(Node),
-                                     Node->getValueType(0),
-                                     Node->getOperand(1));
-      Results.push_back(DAG.getNode(ISD::FPOW, SDLoc(Node),
-                                    Node->getValueType(0), Node->getOperand(0),
-                                    Exponent));
+      if (Node->isStrictFPOpcode()) {
+        SDValue Exponent =
+            DAG.getNode(ISD::STRICT_SINT_TO_FP, SDLoc(Node),
+                        {Node->getValueType(0), Node->getValueType(1)},
+                        {Node->getOperand(0), Node->getOperand(2)});
+        SDValue FPOW =
+            DAG.getNode(ISD::STRICT_FPOW, SDLoc(Node),
+                        {Node->getValueType(0), Node->getValueType(1)},
+                        {Exponent.getValue(1), Node->getOperand(1), Exponent});
+        Results.push_back(FPOW);
+        Results.push_back(FPOW.getValue(1));
+      } else {
+        SDValue Exponent =
+            DAG.getNode(ISD::SINT_TO_FP, SDLoc(Node), Node->getValueType(0),
+                        Node->getOperand(1));
+        Results.push_back(DAG.getNode(ISD::FPOW, SDLoc(Node),
+                                      Node->getValueType(0),
+                                      Node->getOperand(0), Exponent));
+      }
       break;
     }
     unsigned Offset = Node->isStrictFPOpcode() ? 1 : 0;

llvm/test/CodeGen/X86/float-strict-powi-convert.ll

@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-pc-windows-msvc %s -o - | FileCheck %s -check-prefix=WIN
+; RUN: llc -mtriple=x86_64-pc-linux %s -o -| FileCheck %s -check-prefix=UNIX
+
+declare float @llvm.experimental.constrained.powi.f32.i32(float, i32, metadata, metadata)
+
+define float @powi_f64(float %a, i32 %b) nounwind strictfp {
+; WIN-LABEL: powi_f64:
+; WIN:       # %bb.0:
+; WIN-NEXT:    subq $40, %rsp
+; WIN-NEXT:    cvtsi2ss %edx, %xmm1
+; WIN-NEXT:    callq powf
+; WIN-NEXT:    addq $40, %rsp
+; WIN-NEXT:    retq
+;
+; UNIX-LABEL: powi_f64:
+; UNIX:       # %bb.0:
+; UNIX-NEXT:    pushq %rax
+; UNIX-NEXT:    callq __powisf2@PLT
+; UNIX-NEXT:    popq %rax
+; UNIX-NEXT:    retq
+  %1 = call float @llvm.experimental.constrained.powi.f32.i32(float %a, i32 %b, metadata !"round.tonearest", metadata !"fpexcept.ignore") strictfp
+  ret float %1
+}