[llvm] [AMDGPU] Support D16 folding for image.sample with multiple extractelement and fptrunc users (PR #141758)

[Jay Foad via llvm-commits]

================
@@ -269,6 +269,68 @@ simplifyAMDGCNImageIntrinsic(const GCNSubtarget *ST,
                                        ArgTys[0] = User->getType();
                                      });
         }
+      } else {
----------------
jayfoad wrote:

I think it would make a bit more sense to put all of this inside:
```
  if (II.getType().isVectorTy()) {
    new code here
  } else {
    old code here
  }
```

https://github.com/llvm/llvm-project/pull/141758