[llvm] [Xtensa] Implement Xtensa Floating Point Option. (PR #136086)

[Matt Arsenault via llvm-commits]

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@@ -815,6 +898,21 @@ SDValue XtensaTargetLowering::LowerImmediate(SDValue Op,
   return Op;
 }
 
+SDValue XtensaTargetLowering::LowerImmediateFP(SDValue Op,
+                                               SelectionDAG &DAG) const {
+  const ConstantFPSDNode *CN = cast<ConstantFPSDNode>(Op);
+  SDLoc DL(CN);
+  APFloat apval = CN->getValueAPF();
+  int64_t value = llvm::bit_cast<uint32_t>(CN->getValueAPF().convertToFloat());
+  if (Op.getValueType() == MVT::f32) {
+    Type *Ty = Type::getInt32Ty(*DAG.getContext());
+    Constant *CV = ConstantInt::get(Ty, value);
+    SDValue CP = DAG.getConstantPool(CV, MVT::i32);
+    return DAG.getNode(ISD::BITCAST, DL, MVT::f32, CP);
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arsenm wrote:

This usage of ConstantPool looks broken, it gives a pointer that you're supposed to load the value from. How can you interpret the pointer value as an FP type? 

https://github.com/llvm/llvm-project/pull/136086