[SPIR-V] Improve type inference: deduce types of composite data structures (#86782)

This PR improves type inference in general and deduces types of
composite data structures in particular. Also added a way to insert a
bitcast to make a fun call valid in case of arguments types mismatch due
to opaque pointers type inference.

The attached test `pointers/nested-struct-opaque-pointers.ll`
demonstrates new capabilities: the SPIRV code emitted for this test is
now (1) valid in a sense of data field types and (2) accepted by
`spirv-val`.

More strict LIT checks, support of more composite data structures and
improvement of fun calls from the perspective of type correctness are
main todo's at the moment.

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp

@@ -201,21 +201,30 @@ static SPIRVType *getArgSPIRVType(const Function &F, unsigned ArgIdx,
   if (!isPointerTy(OriginalArgType))
     return GR->getOrCreateSPIRVType(OriginalArgType, MIRBuilder, ArgAccessQual);
 
-  // In case OriginalArgType is of pointer type, there are three possibilities:
+  Argument *Arg = F.getArg(ArgIdx);
+  Type *ArgType = Arg->getType();
+  if (isTypedPointerTy(ArgType)) {
+    SPIRVType *ElementType = GR->getOrCreateSPIRVType(
+        cast<TypedPointerType>(ArgType)->getElementType(), MIRBuilder);
+    return GR->getOrCreateSPIRVPointerType(
+        ElementType, MIRBuilder,
+        addressSpaceToStorageClass(getPointerAddressSpace(ArgType), ST));
+  }
+
+  // In case OriginalArgType is of untyped pointer type, there are three
+  // possibilities:
   // 1) This is a pointer of an LLVM IR element type, passed byval/byref.
   // 2) This is an OpenCL/SPIR-V builtin type if there is spv_assign_type
-  // intrinsic assigning a TargetExtType.
+  //    intrinsic assigning a TargetExtType.
   // 3) This is a pointer, try to retrieve pointer element type from a
   // spv_assign_ptr_type intrinsic or otherwise use default pointer element
   // type.
-  Argument *Arg = F.getArg(ArgIdx);
-  if (HasPointeeTypeAttr(Arg)) {
-    Type *ByValRefType = Arg->hasByValAttr() ? Arg->getParamByValType()
-                                             : Arg->getParamByRefType();
-    SPIRVType *ElementType = GR->getOrCreateSPIRVType(ByValRefType, MIRBuilder);
+  if (hasPointeeTypeAttr(Arg)) {
+    SPIRVType *ElementType =
+        GR->getOrCreateSPIRVType(getPointeeTypeByAttr(Arg), MIRBuilder);
     return GR->getOrCreateSPIRVPointerType(
         ElementType, MIRBuilder,
-        addressSpaceToStorageClass(getPointerAddressSpace(Arg->getType()), ST));
+        addressSpaceToStorageClass(getPointerAddressSpace(ArgType), ST));
   }
 
   for (auto User : Arg->users()) {