[clang][SPIRV] Add builtin for OpGenericCastToPtrExplicit and its SPIR-V friendly binding (#137805)

The patch introduce __builtin_spirv_generic_cast_to_ptr_explicit which
is lowered to the llvm.spv.generic.cast.to.ptr.explicit intrinsic.

The SPIR-V builtins are now split into 3 differents file:
BuiltinsSPIRVCore.td,
BuiltinsSPIRVVK.td for Vulkan specific builtins, BuiltinsSPIRVCL.td for
OpenCL specific builtins
and BuiltinsSPIRVCommon.td for common ones.

The patch also introduces a new header defining its SPIR-V friendly
equivalent (__spirv_GenericCastToPtrExplicit_ToGlobal,
__spirv_GenericCastToPtrExplicit_ToLocal and
__spirv_GenericCastToPtrExplicit_ToPrivate). The functions are declared
as aliases to the new builtin allowing C-like languages to have a
definition to rely on as well as gaining proper front-end diagnostics.

The motivation for the header is to provide a stable binding for
applications or library (such as SYCL) and allows non SPIR-V targets to
provide an implementation (via libclc or similar to how it is done for
gpuintrin.h).

Author: Naghasan

clang/include/clang/Basic/BuiltinsSPIRV.td

@@ -0,0 +1,15 @@
+//===--- BuiltinsSPIRVBase.td - SPIRV Builtin function database -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+include "clang/Basic/BuiltinsBase.td"
+
+class SPIRVBuiltin<string prototype, list<Attribute> Attr> : Builtin {
+  let Spellings = ["__builtin_spirv_"#NAME];
+  let Prototype = prototype;
+  let Attributes = !listconcat([NoThrow], Attr);
+}

clang/include/clang/Basic/BuiltinsSPIRVBase.td

@@ -0,0 +1,12 @@
+//===--- BuiltinsSPIRVCL.td - SPIRV Builtin function database ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+include "clang/Basic/BuiltinsSPIRVBase.td"
+
+def generic_cast_to_ptr_explicit
+    : SPIRVBuiltin<"void*(void*, int)", [NoThrow, Const, CustomTypeChecking]>;

clang/include/clang/Basic/BuiltinsSPIRVCL.td

@@ -0,0 +1,13 @@
+//===- BuiltinsSPIRVCommon.td - SPIRV Builtin function database -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+include "clang/Basic/BuiltinsSPIRVBase.td"
+
+def distance : SPIRVBuiltin<"void(...)", [NoThrow, Const]>;
+def length : SPIRVBuiltin<"void(...)", [NoThrow, Const]>;
+def smoothstep : SPIRVBuiltin<"void(...)", [NoThrow, Const, CustomTypeChecking]>;

clang/include/clang/Basic/BuiltinsSPIRVCommon.td

@@ -0,0 +1,13 @@
+//===--- BuiltinsSPIRVVK.td - SPIRV Builtin function database ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+include "clang/Basic/BuiltinsSPIRVBase.td"
+
+
+def reflect : SPIRVBuiltin<"void(...)", [NoThrow, Const]>;
+def faceforward : SPIRVBuiltin<"void(...)", [NoThrow, Const, CustomTypeChecking]>;

clang/include/clang/Basic/BuiltinsSPIRVVK.td

@@ -109,9 +109,17 @@ clang_tablegen(BuiltinsRISCV.inc -gen-clang-builtins
   SOURCE BuiltinsRISCV.td
   TARGET ClangBuiltinsRISCV)
 
-clang_tablegen(BuiltinsSPIRV.inc -gen-clang-builtins
-  SOURCE BuiltinsSPIRV.td
-  TARGET ClangBuiltinsSPIRV)
+clang_tablegen(BuiltinsSPIRVCommon.inc -gen-clang-builtins
+  SOURCE BuiltinsSPIRVCommon.td
+  TARGET ClangBuiltinsSPIRVCommon)
+
+clang_tablegen(BuiltinsSPIRVVK.inc -gen-clang-builtins
+  SOURCE BuiltinsSPIRVVK.td
+  TARGET ClangBuiltinsSPIRVVK)
+
+clang_tablegen(BuiltinsSPIRVCL.inc -gen-clang-builtins
+  SOURCE BuiltinsSPIRVCL.td
+  TARGET ClangBuiltinsSPIRVCL)
 
 clang_tablegen(BuiltinsX86.inc -gen-clang-builtins
   SOURCE BuiltinsX86.td

clang/include/clang/Basic/CMakeLists.txt

@@ -4679,7 +4679,7 @@ def err_attribute_preferred_name_arg_invalid : Error<
   "argument %0 to 'preferred_name' attribute is not a typedef for "
   "a specialization of %1">;
 def err_attribute_builtin_alias : Error<
-  "%0 attribute can only be applied to a ARM, HLSL or RISC-V builtin">;
+  "%0 attribute can only be applied to a ARM, HLSL, SPIR-V or RISC-V builtin">;
 
 // called-once attribute diagnostics.
 def err_called_once_attribute_wrong_type : Error<
@@ -12878,6 +12878,16 @@ def err_bit_int_bad_size : Error<"%select{signed|unsigned}0 _BitInt must "
 def err_bit_int_max_size : Error<"%select{signed|unsigned}0 _BitInt of bit "
                                  "sizes greater than %1 not supported">;
 
+// SPIR-V builtins diagnostics
+def err_spirv_invalid_target : Error<
+   "builtin requires %select{spirv|spirv32 or spirv64}0 target">;
+def err_spirv_builtin_generic_cast_invalid_arg : Error<
+  "expecting a pointer argument to the generic address space">;
+def err_spirv_enum_not_int : Error<
+   "%0{storage class} argument for SPIR-V builtin is not a 32-bits integer">;
+def err_spirv_enum_not_valid : Error<
+   "invalid value for %select{storage class}0 argument">;
+
 // errors of expect.with.probability
 def err_probability_not_constant_float : Error<
    "probability argument to __builtin_expect_with_probability must be constant "

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -157,7 +157,17 @@ namespace clang {
   enum {
     LastTIBuiltin = clang::Builtin::FirstTSBuiltin - 1,
 #define GET_BUILTIN_ENUMERATORS
-#include "clang/Basic/BuiltinsSPIRV.inc"
+#include "clang/Basic/BuiltinsSPIRVCommon.inc"
+#undef GET_BUILTIN_ENUMERATORS
+    FirstVKBuiltin,
+    LastCoreBuiltin = FirstVKBuiltin - 1,
+#define GET_BUILTIN_ENUMERATORS
+#include "clang/Basic/BuiltinsSPIRVVK.inc"
+#undef GET_BUILTIN_ENUMERATORS
+    FirstCLBuiltin,
+    LastVKBuiltin = FirstCLBuiltin - 1,
+#define GET_BUILTIN_ENUMERATORS
+#include "clang/Basic/BuiltinsSPIRVCL.inc"
 #undef GET_BUILTIN_ENUMERATORS
     LastTSBuiltin
   };

clang/include/clang/Basic/TargetBuiltins.h

@@ -21,7 +21,8 @@ class SemaSPIRV : public SemaBase {
 public:
   SemaSPIRV(Sema &S);
 
-  bool CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
+  bool CheckSPIRVBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
+                                     CallExpr *TheCall);
 };
 } // namespace clang
 

clang/include/clang/Sema/SemaSPIRV.h

@@ -10165,6 +10165,11 @@ bool ASTContext::canBuiltinBeRedeclared(const FunctionDecl *FD) const {
   if (LangOpts.HLSL && FD->getBuiltinID() != Builtin::NotBuiltin &&
       BuiltinInfo.hasCustomTypechecking(FD->getBuiltinID()))
     return true;
+  // Allow redecl custom type checking builtin for SPIR-V.
+  if (getTargetInfo().getTriple().isSPIROrSPIRV() &&
+      BuiltinInfo.isTSBuiltin(FD->getBuiltinID()) &&
+      BuiltinInfo.hasCustomTypechecking(FD->getBuiltinID()))
+    return true;
   return BuiltinInfo.canBeRedeclared(FD->getBuiltinID());
 }