[clang][SPIRV] Add builtin for OpGenericCastToPtrExplicit and its SPIR-V friendly binding

Naghasan · Naghasan · commit 90725e8f7429 · 2025-04-29T14:20:25.000+01:00
The patch introduce __builtin_spirv_generic_cast_to_ptr_explicit which is lowered to
the llvm.spv.generic.cast.to.ptr.explicit intrinsic.

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.
diff --git a/clang/include/clang/Basic/BuiltinsSPIRV.td b/clang/include/clang/Basic/BuiltinsSPIRV.td
@@ -8,6 +8,12 @@
 
 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);
+}
+
 def SPIRVDistance : Builtin {
   let Spellings = ["__builtin_spirv_distance"];
   let Attributes = [NoThrow, Const];
@@ -37,3 +43,6 @@ def SPIRVFaceForward : Builtin {
   let Attributes = [NoThrow, Const, CustomTypeChecking];
   let Prototype = "void(...)";
 }
+
+def generic_cast_to_ptr_explicit
+    : SPIRVBuiltin<"void*(void*, int)", [NoThrow, Const, CustomTypeChecking]>;
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4609,7 +4609,7 @@ 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<
@@ -12740,6 +12740,14 @@ 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_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 "
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -10054,6 +10054,11 @@ 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());
 }
 
diff --git a/clang/lib/Basic/Targets/SPIR.cpp b/clang/lib/Basic/Targets/SPIR.cpp
@@ -35,8 +35,10 @@ static constexpr Builtin::Info BuiltinInfos[] = {
 static_assert(std::size(BuiltinInfos) == NumBuiltins);
 
 llvm::SmallVector<Builtin::InfosShard>
-SPIRVTargetInfo::getTargetBuiltins() const {
-  return {{&BuiltinStrings, BuiltinInfos}};
+BaseSPIRTargetInfo::getTargetBuiltins() const {
+  if (getTriple().isSPIRV())
+    return {{&BuiltinStrings, BuiltinInfos}};
+  return {};
 }
 
 void SPIRTargetInfo::getTargetDefines(const LangOptions &Opts,
diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
@@ -164,9 +164,7 @@ class LLVM_LIBRARY_VISIBILITY BaseSPIRTargetInfo : public TargetInfo {
   // memcpy as per section 3 of the SPIR spec.
   bool useFP16ConversionIntrinsics() const override { return false; }
 
-  llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const override {
-    return {};
-  }
+  llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const override;
 
   std::string_view getClobbers() const override { return ""; }
 
@@ -321,8 +319,6 @@ class LLVM_LIBRARY_VISIBILITY SPIRVTargetInfo : public BaseSPIRVTargetInfo {
                     "v256:256-v512:512-v1024:1024-n8:16:32:64-G10");
   }
 
-  llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const override;
-
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override;
 };
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -97,10 +97,10 @@ static Value *EmitTargetArchBuiltinExpr(CodeGenFunction *CGF,
   case llvm::Triple::riscv64:
     return CGF->EmitRISCVBuiltinExpr(BuiltinID, E, ReturnValue);
   case llvm::Triple::spirv:
-    return CGF->EmitSPIRVBuiltinExpr(BuiltinID, E);
+  case llvm::Triple::spirv32:
   case llvm::Triple::spirv64:
     if (CGF->getTarget().getTriple().getOS() != llvm::Triple::OSType::AMDHSA)
-      return nullptr;
+      return CGF->EmitSPIRVBuiltinExpr(BuiltinID, E);
     return CGF->EmitAMDGPUBuiltinExpr(BuiltinID, E);
   default:
     return nullptr;
diff --git a/clang/lib/CodeGen/TargetBuiltins/SPIR.cpp b/clang/lib/CodeGen/TargetBuiltins/SPIR.cpp
@@ -83,6 +83,20 @@ Value *CodeGenFunction::EmitSPIRVBuiltinExpr(unsigned BuiltinID,
         /*ReturnType=*/N->getType(), Intrinsic::spv_faceforward,
         ArrayRef<Value *>{N, I, Ng}, /*FMFSource=*/nullptr, "spv.faceforward");
   }
+  case SPIRV::BI__builtin_spirv_generic_cast_to_ptr_explicit: {
+    Value *Ptr = EmitScalarExpr(E->getArg(0));
+    assert(E->getArg(0)->getType()->hasPointerRepresentation() &&
+           E->getArg(1)->getType()->hasIntegerRepresentation() &&
+           "GenericCastToPtrExplicit takes a pointer and an int");
+    llvm::Type *Res = getTypes().ConvertType(E->getType());
+    assert(Res->isPointerTy() &&
+           "GenericCastToPtrExplicit doesn't return a pointer");
+    llvm::CallInst *Call = Builder.CreateIntrinsic(
+        /*ReturnType=*/Res, Intrinsic::spv_generic_cast_to_ptr_explicit,
+        ArrayRef<Value *>{Ptr}, nullptr, "spv.generic_cast");
+    Call->addRetAttr(llvm::Attribute::AttrKind::NoUndef);
+    return Call;
+  }
   }
   return nullptr;
 }
diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
@@ -129,6 +129,10 @@ set(riscv_files
   sifive_vector.h
   )
 
+set(spirv_files
+  __clang_spirv_builtins.h
+  )
+
 set(systemz_files
   s390intrin.h
   vecintrin.h
@@ -316,6 +320,7 @@ set(files
   ${ppc_files}
   ${ppc_htm_files}
   ${riscv_files}
+  ${spirv_files}
   ${systemz_files}
   ${ve_files}
   ${x86_files}
@@ -526,6 +531,7 @@ add_dependencies("clang-resource-headers"
                  "ppc-resource-headers"
                  "ppc-htm-resource-headers"
                  "riscv-resource-headers"
+                 "spirv-resource-headers"
                  "systemz-resource-headers"
                  "ve-resource-headers"
                  "webassembly-resource-headers"
@@ -559,6 +565,7 @@ add_header_target("gpu-resource-headers" "${gpu_files}")
 
 # Other header groupings
 add_header_target("hlsl-resource-headers" ${hlsl_files})
+add_header_target("spirv-resource-headers" ${spirv_files})
 add_header_target("opencl-resource-headers" ${opencl_files})
 add_header_target("llvm-libc-resource-headers" ${llvm_libc_wrapper_files})
 add_header_target("openmp-resource-headers" ${openmp_wrapper_files})
@@ -764,6 +771,12 @@ install(
   ${EXCLUDE_HLSL}
   COMPONENT hlsl-resource-headers)
 
+install(
+  FILES ${spirv_files}
+  DESTINATION ${header_install_dir}
+  EXCLUDE_FROM_ALL
+  COMPONENT spirv-resource-headers)
+
 install(
   FILES ${opencl_files}
   DESTINATION ${header_install_dir}
@@ -833,6 +846,9 @@ if (NOT LLVM_ENABLE_IDE)
   add_llvm_install_targets(install-riscv-resource-headers
                            DEPENDS riscv-resource-headers
                            COMPONENT riscv-resource-headers)
+  add_llvm_install_targets(install-spirv-resource-headers
+                           DEPENDS spirv-resource-headers
+                           COMPONENT spirv-resource-headers)
   add_llvm_install_targets(install-systemz-resource-headers
                            DEPENDS systemz-resource-headers
                            COMPONENT systemz-resource-headers)
diff --git a/clang/lib/Headers/__clang_spirv_builtins.h b/clang/lib/Headers/__clang_spirv_builtins.h
@@ -0,0 +1,179 @@
+/*===---- spirv_builtin_vars.h - SPIR-V built-in ---------------------------===
+ *
+ * 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
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#ifndef __SPIRV_BUILTIN_VARS_H
+#define __SPIRV_BUILTIN_VARS_H
+
+#if __cplusplus >= 201103L
+#define __SPIRV_NOEXCEPT noexcept
+#else
+#define __SPIRV_NOEXCEPT
+#endif
+
+#define __SPIRV_overloadable __attribute__((overloadable))
+#define __SPIRV_convergent __attribute__((convergent))
+#define __SPIRV_inline __attribute__((always_inline))
+
+#define __global __attribute__((opencl_global))
+#define __local __attribute__((opencl_local))
+#define __private __attribute__((opencl_private))
+#define __constant __attribute__((opencl_constant))
+#ifdef __SYCL_DEVICE_ONLY__
+#define __generic
+#else
+#define __generic __attribute__((opencl_generic))
+#endif
+
+// Check if SPIR-V builtins are supported.
+// As the translator doesn't use the LLVM intrinsics (which would be emitted if
+// we use the SPIR-V builtins) we can't rely on the SPIRV32/SPIRV64 etc macros
+// to establish if we can use the builtin alias. We disable builtin altogether
+// if we do not intent to use the backend. So instead of use target macros, rely
+// on a __has_builtin test.
+#if (__has_builtin(__builtin_spirv_generic_cast_to_ptr_explicit))
+#define __SPIRV_BUILTIN_ALIAS(builtin)                                         \
+  __attribute__((clang_builtin_alias(builtin)))
+#else
+#define __SPIRV_BUILTIN_ALIAS(builtin)
+#endif
+
+// OpGenericCastToPtrExplicit
+
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__global void *__spirv_GenericCastToPtrExplicit_ToGlobal(__generic void *,
+                                                         int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__global const void *
+__spirv_GenericCastToPtrExplicit_ToGlobal(__generic const void *,
+                                          int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__global volatile void *
+__spirv_GenericCastToPtrExplicit_ToGlobal(__generic volatile void *,
+                                          int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__global const volatile void *
+__spirv_GenericCastToPtrExplicit_ToGlobal(__generic const volatile void *,
+                                          int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__local void *__spirv_GenericCastToPtrExplicit_ToLocal(__generic void *,
+                                                       int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__local const void *
+__spirv_GenericCastToPtrExplicit_ToLocal(__generic const void *,
+                                         int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__local volatile void *
+__spirv_GenericCastToPtrExplicit_ToLocal(__generic volatile void *,
+                                         int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__local const volatile void *
+__spirv_GenericCastToPtrExplicit_ToLocal(__generic const volatile void *,
+                                         int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__private void *
+__spirv_GenericCastToPtrExplicit_ToPrivate(__generic void *,
+                                           int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__private const void *
+__spirv_GenericCastToPtrExplicit_ToPrivate(__generic const void *,
+                                           int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__private volatile void *
+__spirv_GenericCastToPtrExplicit_ToPrivate(__generic volatile void *,
+                                           int) __SPIRV_NOEXCEPT;
+extern __SPIRV_overloadable
+__SPIRV_BUILTIN_ALIAS(__builtin_spirv_generic_cast_to_ptr_explicit)
+__private const volatile void *
+__spirv_GenericCastToPtrExplicit_ToPrivate(__generic const volatile void *,
+                                           int) __SPIRV_NOEXCEPT;
+
+// OpGenericCastToPtr
+
+static __SPIRV_overloadable __SPIRV_inline __global void *
+__spirv_GenericCastToPtr_ToGlobal(__generic void *p, int) __SPIRV_NOEXCEPT {
+  return (__global void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __global const void *
+__spirv_GenericCastToPtr_ToGlobal(__generic const void *p,
+                                  int) __SPIRV_NOEXCEPT {
+  return (__global const void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __global volatile void *
+__spirv_GenericCastToPtr_ToGlobal(__generic volatile void *p,
+                                  int) __SPIRV_NOEXCEPT {
+  return (__global volatile void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __global const volatile void *
+__spirv_GenericCastToPtr_ToGlobal(__generic const volatile void *p,
+                                  int) __SPIRV_NOEXCEPT {
+  return (__global const volatile void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __local void *
+__spirv_GenericCastToPtr_ToLocal(__generic void *p, int) __SPIRV_NOEXCEPT {
+  return (__local void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __local const void *
+__spirv_GenericCastToPtr_ToLocal(__generic const void *p,
+                                 int) __SPIRV_NOEXCEPT {
+  return (__local const void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __local volatile void *
+__spirv_GenericCastToPtr_ToLocal(__generic volatile void *p,
+                                 int) __SPIRV_NOEXCEPT {
+  return (__local volatile void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __local const volatile void *
+__spirv_GenericCastToPtr_ToLocal(__generic const volatile void *p,
+                                 int) __SPIRV_NOEXCEPT {
+  return (__local const volatile void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __private void *
+__spirv_GenericCastToPtr_ToPrivate(__generic void *p, int) __SPIRV_NOEXCEPT {
+  return (__private void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __private const void *
+__spirv_GenericCastToPtr_ToPrivate(__generic const void *p,
+                                   int) __SPIRV_NOEXCEPT {
+  return (__private const void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __private volatile void *
+__spirv_GenericCastToPtr_ToPrivate(__generic volatile void *p,
+                                   int) __SPIRV_NOEXCEPT {
+  return (__private volatile void *)p;
+}
+static __SPIRV_overloadable __SPIRV_inline __private const volatile void *
+__spirv_GenericCastToPtr_ToPrivate(__generic const volatile void *p,
+                                   int) __SPIRV_NOEXCEPT {
+  return (__private const volatile void *)p;
+}
+
+#undef __SPIRV_overloadable
+#undef __SPIRV_convergent
+#undef __SPIRV_inline
+
+#undef __global
+#undef __local
+#undef __constant
+#undef __generic
+
+#undef __SPIRV_BUILTIN_ALIAS
+#undef __SPIRV_NOEXCEPT
+
+#endif /* __SPIRV_BUILTIN_VARS_H */
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
@@ -1983,7 +1983,11 @@ bool Sema::CheckTSBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
   case llvm::Triple::mips64el:
     return MIPS().CheckMipsBuiltinFunctionCall(TI, BuiltinID, TheCall);
   case llvm::Triple::spirv:
-    return SPIRV().CheckSPIRVBuiltinFunctionCall(BuiltinID, TheCall);
+  case llvm::Triple::spirv32:
+  case llvm::Triple::spirv64:
+    if (TI.getTriple().getOS() != llvm::Triple::OSType::AMDHSA)
+      return SPIRV().CheckSPIRVBuiltinFunctionCall(BuiltinID, TheCall);
+    return false;
   case llvm::Triple::systemz:
     return SystemZ().CheckSystemZBuiltinFunctionCall(BuiltinID, TheCall);
   case llvm::Triple::x86:
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -53,6 +53,7 @@
 #include "clang/Sema/SemaOpenCL.h"
 #include "clang/Sema/SemaOpenMP.h"
 #include "clang/Sema/SemaRISCV.h"
+#include "clang/Sema/SemaSPIRV.h"
 #include "clang/Sema/SemaSYCL.h"
 #include "clang/Sema/SemaSwift.h"
 #include "clang/Sema/SemaWasm.h"
@@ -5837,12 +5838,13 @@ static void handleBuiltinAliasAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   bool IsAArch64 = S.Context.getTargetInfo().getTriple().isAArch64();
   bool IsARM = S.Context.getTargetInfo().getTriple().isARM();
   bool IsRISCV = S.Context.getTargetInfo().getTriple().isRISCV();
+  bool IsSPIRV = S.Context.getTargetInfo().getTriple().isSPIRV();
   bool IsHLSL = S.Context.getLangOpts().HLSL;
   if ((IsAArch64 && !S.ARM().SveAliasValid(BuiltinID, AliasName)) ||
       (IsARM && !S.ARM().MveAliasValid(BuiltinID, AliasName) &&
        !S.ARM().CdeAliasValid(BuiltinID, AliasName)) ||
       (IsRISCV && !S.RISCV().isAliasValid(BuiltinID, AliasName)) ||
-      (!IsAArch64 && !IsARM && !IsRISCV && !IsHLSL)) {
+      (!IsAArch64 && !IsARM && !IsRISCV && !IsHLSL && !IsSPIRV)) {
     S.Diag(AL.getLoc(), diag::err_attribute_builtin_alias) << AL;
     return;
   }
diff --git a/clang/lib/Sema/SemaSPIRV.cpp b/clang/lib/Sema/SemaSPIRV.cpp
diff --git a/clang/test/CodeGenSPIRV/Builtins/generic_cast_to_ptr_explicit.c b/clang/test/CodeGenSPIRV/Builtins/generic_cast_to_ptr_explicit.c
diff --git a/clang/test/Headers/spirv_functions.cpp b/clang/test/Headers/spirv_functions.cpp
diff --git a/clang/test/SemaSPIRV/BuiltIns/generic_cast_to_ptr_explicit.c b/clang/test/SemaSPIRV/BuiltIns/generic_cast_to_ptr_explicit.c
