[clang][SPIRV] Don't addrspacecast nullptr for function pointer types

Signed-off-by: Nick Sarnie <[email protected]>

Author: sarnex

clang/lib/CodeGen/Targets/SPIR.cpp

@@ -260,8 +260,16 @@ CommonSPIRTargetCodeGenInfo::getNullPointer(const CodeGen::CodeGenModule &CGM,
   LangAS AS = QT->getUnqualifiedDesugaredType()->isNullPtrType()
                   ? LangAS::Default
                   : QT->getPointeeType().getAddressSpace();
+  unsigned ASAsInt = static_cast<unsigned>(AS);
+  unsigned FirstTargetASAsInt =
+      static_cast<unsigned>(LangAS::FirstTargetAddressSpace);
+  unsigned CodeSectionINTELAS = FirstTargetASAsInt + 9;
+  // As per SPV_INTEL_function_pointers, it is illegal to addrspacecast
+  // function pointers to/from the generic AS.
+  bool IsFunctionPtrAS =
+      CGM.getTriple().isSPIRV() && ASAsInt == CodeSectionINTELAS;
   if (AS == LangAS::Default || AS == LangAS::opencl_generic ||
-      AS == LangAS::opencl_constant)
+      AS == LangAS::opencl_constant || IsFunctionPtrAS)
     return llvm::ConstantPointerNull::get(PT);
 
   auto &Ctx = CGM.getContext();

clang/test/CodeGenSPIRV/spirv-intel.c

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -triple spirv64-intel %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-WITH-64 %s
-// RUN: %clang_cc1 -triple spirv32-intel %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-WITH-32 %s
+// RUN: %clang_cc1 -triple spirv64-intel %s -emit-llvm -o - | FileCheck -check-prefixes=CHECK-WITH,CHECK-WITH-64 %s
+// RUN: %clang_cc1 -triple spirv32-intel %s -emit-llvm -o - | FileCheck -check-prefixes=CHECK-WITH,CHECK-WITH-32 %s
 // RUN: %clang_cc1 -triple spir-intel %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-WITHOUT %s
 // RUN: %clang_cc1 -triple spir64-intel %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-WITHOUT %s
 
@@ -9,3 +9,11 @@
 // CHECK-WITHOUT: spir_func void @foo(ptr noundef %param) #0 {
 void foo(int *param) {
 }
+
+typedef __attribute__((address_space(9))) void * FnPtrTy;
+
+// CHECK-WITH: %{{.*}} = icmp eq ptr addrspace(9) %{{.*}}, null
+int bar() {
+  FnPtrTy FnPtr = (FnPtrTy)foo;
+  return FnPtr == 0;
+}