DAG: Add RTLIB::getPOW helper (#147274)

Co-authored-by: Paul Walker <paul.walker@arm.com>

Author: arsenm

llvm/include/llvm/CodeGen/RuntimeLibcallUtil.h

@@ -56,6 +56,10 @@ LLVM_ABI Libcall getUINTTOFP(EVT OpVT, EVT RetVT);
 /// UNKNOWN_LIBCALL if there is none.
 LLVM_ABI Libcall getPOWI(EVT RetVT);
 
+/// getPOW - Return the POW_* value for the given types, or
+/// UNKNOWN_LIBCALL if there is none.
+LLVM_ABI Libcall getPOW(EVT RetVT);
+
 /// getLDEXP - Return the LDEXP_* value for the given types, or
 /// UNKNOWN_LIBCALL if there is none.
 LLVM_ABI Libcall getLDEXP(EVT RetVT);

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

@@ -704,12 +704,7 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_FP_ROUND(SDNode *N) {
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatRes_FPOW(SDNode *N) {
-  return SoftenFloatRes_Binary(N, GetFPLibCall(N->getValueType(0),
-                                               RTLIB::POW_F32,
-                                               RTLIB::POW_F64,
-                                               RTLIB::POW_F80,
-                                               RTLIB::POW_F128,
-                                               RTLIB::POW_PPCF128));
+  return SoftenFloatRes_Binary(N, RTLIB::getPOW(N->getValueType(0)));
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatRes_ExpOp(SDNode *N) {
@@ -723,6 +718,9 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_ExpOp(SDNode *N) {
                              : RTLIB::getLDEXP(N->getValueType(0));
   assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unexpected fpowi.");
   if (!TLI.getLibcallName(LC)) {
+    RTLIB::Libcall NewLC = RTLIB::getPOW(N->getValueType(0));
+    assert(NewLC != RTLIB::UNKNOWN_LIBCALL && "Unexpected fpow type");
+
     // Some targets don't have a powi libcall; use pow instead.
     // FIXME: Implement this if some target needs it.
     DAG.getContext()->emitError("do not know how to soften fpowi to fpow");

llvm/lib/CodeGen/TargetLoweringBase.cpp

@@ -396,6 +396,10 @@ RTLIB::Libcall RTLIB::getPOWI(EVT RetVT) {
                       POWI_PPCF128);
 }
 
+RTLIB::Libcall RTLIB::getPOW(EVT RetVT) {
+  return getFPLibCall(RetVT, POW_F32, POW_F64, POW_F80, POW_F128, POW_PPCF128);
+}
+
 RTLIB::Libcall RTLIB::getLDEXP(EVT RetVT) {
   return getFPLibCall(RetVT, LDEXP_F32, LDEXP_F64, LDEXP_F80, LDEXP_F128,
                       LDEXP_PPCF128);