[llvm] [InstCombine] Fix Failure to convert vector fp comparisons that can be represented as integers #82241 (PR #83274)

[Yingwei Zheng via llvm-commits]

================
@@ -7286,6 +7286,10 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
 Instruction *InstCombinerImpl::foldFCmpIntToFPConst(FCmpInst &I,
                                                     Instruction *LHSI,
                                                     Constant *RHSC) {
+  if (RHSC->getType()->isVectorTy()) {
+    if (Constant *CV = RHSC->getSplatValue(false))
+      RHSC = CV;
+  }
   if (!isa<ConstantFP>(RHSC)) return nullptr;
   const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
----------------
dtcxzyw wrote:

```suggestion
  const APFloat *RHS;
  if (!match(RHSC, m_APFloat(RHS)))
    return nullptr;
```


https://github.com/llvm/llvm-project/pull/83274