Add BitCast instructions from float to int for AtomicCmpXchg calls (#3331)

In SPIRV-Translator for `llvm_release_160`, the `BitCast` instruction
from `float` to `int` is currently applied only to argument 2 of the
`AtomicCmpXchg` call. This approach works correctly when using opaque
pointers. However, when typed pointers are present, SPIRV-Translator
must also insert `BitCast` instructions for arguments 0 and 1, as is
done in the `llvm_release_150` branch.

Prior to this change, SPIRV-Translator generated the call
`__spirv_AtomicCompareExchangeWeakPU3AS1fiiiif` for this atomic
operation. After adding the additional `BitCast` instructions, the
generated call becomes `__spirv_AtomicCompareExchangeWeakPU3AS1iiiiii`.

This modification is compatible with both opaque and typed pointers.

The change for llvm_release_150:
663dffd

Author: matborzyszkowski

lib/SPIRV/OCLToSPIRV.cpp

@@ -485,6 +485,22 @@ CallInst *OCLToSPIRVBase::visitCallAtomicCmpXchg(CallInst *CI) {
     if (MemTy->isFloatTy() || MemTy->isDoubleTy()) {
       MemTy =
           MemTy->isFloatTy() ? Type::getInt32Ty(*Ctx) : Type::getInt64Ty(*Ctx);
+
+      if (!Mutator.getArg(0)->getType()->isOpaquePointerTy()) {
+        TypedPointerType *Arg0PtrType = TypedPointerType::get(
+            MemTy, Mutator.getArg(0)->getType()->getPointerAddressSpace());
+        TypedPointerType *Arg1PtrType = TypedPointerType::get(
+            MemTy, Mutator.getArg(1)->getType()->getPointerAddressSpace());
+
+        Mutator.mapArg(0, [=](IRBuilder<> &Builder, Value *V) {
+          return Builder.CreateBitCast(V, Arg0PtrType);
+        });
+
+        Mutator.mapArg(1, [=](IRBuilder<> &Builder, Value *V) {
+          return Builder.CreateBitCast(V, Arg1PtrType);
+        });
+      }
+
       Mutator.replaceArg(
           0,
           {Mutator.getArg(0),