[PowerPC]perform bitcast lowering only at 64 bit

Perform bitcast lowering requires 64-bit to be native supported,
However this is not true on 32-bit targets. Explicitly require
64-bit target.

Fixes #92233

Author: Chen Zheng

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

@@ -9338,7 +9338,7 @@ SDValue PPCTargetLowering::LowerBITCAST(SDValue Op, SelectionDAG &DAG) const {
   if ((Op.getValueType() != MVT::f128) ||
       (Op0.getOpcode() != ISD::BUILD_PAIR) ||
       (Op0.getOperand(0).getValueType() != MVT::i64) ||
-      (Op0.getOperand(1).getValueType() != MVT::i64))
+      (Op0.getOperand(1).getValueType() != MVT::i64) || !Subtarget.isPPC64())
     return SDValue();
 
   return DAG.getNode(PPCISD::BUILD_FP128, dl, MVT::f128, Op0.getOperand(0),

llvm/test/CodeGen/PowerPC/pr92233.ll

@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mcpu=pwr9 -verify-machineinstrs < %s -mtriple=powerpc-unknown-linux-gnu | FileCheck %s
+
+define internal fp128 @f(i128 %v) nounwind {
+; CHECK-LABEL: f:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    stwu 1, -32(1)
+; CHECK-NEXT:    stw 6, 28(1)
+; CHECK-NEXT:    stw 5, 24(1)
+; CHECK-NEXT:    stw 4, 20(1)
+; CHECK-NEXT:    stw 3, 16(1)
+; CHECK-NEXT:    lxv 34, 16(1)
+; CHECK-NEXT:    addi 1, 1, 32
+; CHECK-NEXT:    blr
+entry:
+  %cast = bitcast i128 %v to fp128
+  ret fp128 %cast
+}
+