[llvm] [LLVM][Verifier] Move intrinsic signature verification to declarations (PR #204478)

[Rahul Joshi via llvm-commits]

================
@@ -5883,31 +5911,6 @@ void Verifier::visitInstruction(Instruction &I) {
 /// Allow intrinsics to be verified in different ways.
 void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
   Function *IF = Call.getCalledFunction();
-  Check(IF->isDeclaration(), "Intrinsic functions should never be defined!",
-        IF);
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jurahul wrote:

No, we have a similar check in `visitFunction`:

```
    // Verify that this function (which has a body) is not named "llvm.*".  It
    // is not legal to define intrinsics.
    Check(!IsIntrinsic, "llvm intrinsics cannot be defined!", &F);
```

https://github.com/llvm/llvm-project/pull/204478