[llvm] [X86] getConstVector - remove raw bits -> fp handling and leave it to getNode/FoldConstantArithmetic (PR #135337)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

<details>
<summary>Changes</summary>

getConstVector could only handle f32/f64 vector element types from raw APInt bit data - instead of trying to add all supported fp types, just bitcast the integer equivalent and leave it getNode/FoldConstantArithmetic to perform the constant bitcast conversion

Tentative fix for a regression reported after #<!-- -->133913

---
Full diff: https://github.com/llvm/llvm-project/pull/135337.diff


1 Files Affected:

- (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+2-7) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 42ef817e01456..6e6431008e680 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -4014,6 +4014,7 @@ static SDValue getConstVector(ArrayRef<APInt> Bits, const APInt &Undefs,
   }
 
   MVT EltVT = ConstVecVT.getVectorElementType();
+  MVT EltIntVT = EltVT.changeTypeToInteger();
   for (unsigned i = 0, e = Bits.size(); i != e; ++i) {
     if (Undefs[i]) {
       Ops.append(Split ? 2 : 1, DAG.getUNDEF(EltVT));
@@ -4024,14 +4025,8 @@ static SDValue getConstVector(ArrayRef<APInt> Bits, const APInt &Undefs,
     if (Split) {
       Ops.push_back(DAG.getConstant(V.extractBits(32, 0), dl, EltVT));
       Ops.push_back(DAG.getConstant(V.extractBits(32, 32), dl, EltVT));
-    } else if (EltVT == MVT::f32) {
-      APFloat FV(APFloat::IEEEsingle(), V);
-      Ops.push_back(DAG.getConstantFP(FV, dl, EltVT));
-    } else if (EltVT == MVT::f64) {
-      APFloat FV(APFloat::IEEEdouble(), V);
-      Ops.push_back(DAG.getConstantFP(FV, dl, EltVT));
     } else {
-      Ops.push_back(DAG.getConstant(V, dl, EltVT));
+      Ops.push_back(DAG.getBitcast(EltVT, DAG.getConstant(V, dl, EltIntVT)));
     }
   }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/135337