[SelectionDAG] Support promotion of the FPOWI integer operand

For targets where i32 is not a legal type (e.g. 64-bit RISC-V),
LegalizeIntegerTypes must promote the integer operand of ISD::FPOWI. As this
is a signed value, this should be sign-extended.

This patch enables all tests in test/CodeGen/RISCVfloat-intrinsics.ll for
RV64, as prior to this patch that file couldn't be compiled for RV64 due to an
assertion when performing codegen for fpowi.

Differential Revision: https://reviews.llvm.org/D54574

llvm-svn: 352832

Author: asb

llvm/include/llvm/CodeGen/ISDOpcodes.h

@@ -579,7 +579,9 @@ namespace ISD {
     /// is often a storage-only type but has native conversions.
     FP16_TO_FP, FP_TO_FP16,
 
-    /// Perform various unary floating-point operations inspired by libm.
+    /// Perform various unary floating-point operations inspired by libm. For
+    /// FPOWI, the result is undefined if if the integer operand doesn't fit
+    /// into 32 bits.
     FNEG, FABS, FSQRT, FCBRT, FSIN, FCOS, FPOWI, FPOW,
     FLOG, FLOG2, FLOG10, FEXP, FEXP2,
     FCEIL, FTRUNC, FRINT, FNEARBYINT, FROUND, FFLOOR,

llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp

@@ -1091,6 +1091,8 @@ bool DAGTypeLegalizer::PromoteIntegerOperand(SDNode *N, unsigned OpNo) {
   case ISD::PREFETCH: Res = PromoteIntOp_PREFETCH(N, OpNo); break;
 
   case ISD::SMULFIX: Res = PromoteIntOp_SMULFIX(N); break;
+
+  case ISD::FPOWI: Res = PromoteIntOp_FPOWI(N); break;
   }
 
   // If the result is null, the sub-method took care of registering results etc.
@@ -1474,6 +1476,11 @@ SDValue DAGTypeLegalizer::PromoteIntOp_PREFETCH(SDNode *N, unsigned OpNo) {
                  0);
 }
 
+SDValue DAGTypeLegalizer::PromoteIntOp_FPOWI(SDNode *N) {
+  SDValue Op = SExtPromotedInteger(N->getOperand(1));
+  return SDValue(DAG.UpdateNodeOperands(N, N->getOperand(0), Op), 0);
+}
+
 //===----------------------------------------------------------------------===//
 //  Integer Result Expansion
 //===----------------------------------------------------------------------===//

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h

@@ -379,6 +379,7 @@ class LLVM_LIBRARY_VISIBILITY DAGTypeLegalizer {
   SDValue PromoteIntOp_FRAMERETURNADDR(SDNode *N);
   SDValue PromoteIntOp_PREFETCH(SDNode *N, unsigned OpNo);
   SDValue PromoteIntOp_SMULFIX(SDNode *N);
+  SDValue PromoteIntOp_FPOWI(SDNode *N);
 
   void PromoteSetCCOperands(SDValue &LHS,SDValue &RHS, ISD::CondCode Code);