[CIR][Dialect] Verify bitcast does not contain address space conversion (#813)

Currently some bitcasts would silently change the address space of
source pointer type, which hides some miscompilations of pointer type in
CIR.

#812 is an example. The address space in result pointer type is dropped,
but the bitcast later keep the type consistency no matter what the
result type is. Such bitcast is commonly emitted in CodeGen.

CIR bitcasts are lowered to LLVM bitcasts, which also don't allow
mismatch between address spaces. This PR adds this verification.

Author: seven-mile

clang/lib/CIR/Dialect/IR/CIRDialect.cpp

@@ -510,11 +510,21 @@ LogicalResult CastOp::verify() {
     if (isa<StructType>(srcType) || isa<StructType>(resType))
       return success();
 
+    // Handle the pointer types first.
+    auto srcPtrTy = mlir::dyn_cast<mlir::cir::PointerType>(srcType);
+    auto resPtrTy = mlir::dyn_cast<mlir::cir::PointerType>(resType);
+
+    if (srcPtrTy && resPtrTy) {
+      if (srcPtrTy.getAddrSpace() != resPtrTy.getAddrSpace()) {
+        return emitOpError() << "result type address space does not match the "
+                                "address space of the operand";
+      }
+      return success();
+    }
+
     // This is the only cast kind where we don't want vector types to decay
     // into the element type.
-    if ((!mlir::isa<mlir::cir::PointerType>(getSrc().getType()) ||
-         !mlir::isa<mlir::cir::PointerType>(getResult().getType())) &&
-        (!mlir::isa<mlir::cir::VectorType>(getSrc().getType()) ||
+    if ((!mlir::isa<mlir::cir::VectorType>(getSrc().getType()) ||
          !mlir::isa<mlir::cir::VectorType>(getResult().getType())))
       return emitOpError()
              << "requires !cir.ptr or !cir.vector type for source and result";

clang/test/CIR/IR/invalid.cir

@@ -1298,3 +1298,18 @@ module {
     cir.return
   }
 }
+
+// -----
+
+!s32i = !cir.int<s, 32>
+
+module {
+
+  cir.func @test_bitcast_addrspace() {
+    %0 = cir.alloca !s32i, !cir.ptr<!s32i>, ["tmp"] {alignment = 4 : i64}
+    // expected-error@+1 {{'cir.cast' op result type address space does not match the address space of the operand}}
+    %1 = cir.cast(bitcast, %0 : !cir.ptr<!s32i>), !cir.ptr<!s32i, addrspace(offload_local)>
+  }
+
+}
+