[AMDGPU][clang][CodeGen][opt] Add late-resolved feature identifying predicates #134016
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-clang Author: Alex Voicu (AlexVlx) ChangesThis change adds two semi-magical builtins for AMDGPU:
Neither of these are The motivation for adding these is two-fold:
I've tried to keep the overall footprint of the change small. The changes to Sema are a bit unpleasant, but there was a strong desire to have Clang validate these, and to constrain their uses, and this was the most compact solution I could come up with (suggestions welcome). In the end, I will note there is nothing that is actually AMDGPU specific here, so it is possible that in the future, assuming interests from other targets / users, we'd just promote them to generic intrinsics. Patch is 59.55 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/134016.diff 17 Files Affected:
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 3b8a9cac6587a..8a7cb75af13e5 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -4920,6 +4920,116 @@ If no address spaces names are provided, all address spaces are fenced.
__builtin_amdgcn_fence(__ATOMIC_SEQ_CST, "workgroup", "local")
__builtin_amdgcn_fence(__ATOMIC_SEQ_CST, "workgroup", "local", "global")
+__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+``__builtin_amdgcn_processor_is`` and ``__builtin_amdgcn_is_invocable`` provide
+a functional mechanism for programatically querying:
+
+* the identity of the current target processor;
+* the capability of the current target processor to invoke a particular builtin.
+
+**Syntax**:
+
+.. code-block:: c
+
+ // When used as the predicate for a control structure
+ bool __builtin_amdgcn_processor_is(const char*);
+ bool __builtin_amdgcn_is_invocable(builtin_name);
+ // Otherwise
+ void __builtin_amdgcn_processor_is(const char*);
+ void __builtin_amdgcn_is_invocable(void);
+
+**Example of use**:
+
+.. code-block:: c++
+
+ if (__builtin_amdgcn_processor_is("gfx1201") ||
+ __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var))
+ __builtin_amdgcn_s_sleep_var(x);
+
+ if (!__builtin_amdgcn_processor_is("gfx906"))
+ __builtin_amdgcn_s_wait_event_export_ready();
+ else if (__builtin_amdgcn_processor_is("gfx1010") ||
+ __builtin_amdgcn_processor_is("gfx1101"))
+ __builtin_amdgcn_s_ttracedata_imm(1);
+
+ while (__builtin_amdgcn_processor_is("gfx1101")) *p += x;
+
+ do { *p -= x; } while (__builtin_amdgcn_processor_is("gfx1010"));
+
+ for (; __builtin_amdgcn_processor_is("gfx1201"); ++*p) break;
+
+ if (__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready))
+ __builtin_amdgcn_s_wait_event_export_ready();
+ else if (__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_ttracedata_imm))
+ __builtin_amdgcn_s_ttracedata_imm(1);
+
+ do {
+ *p -= x;
+ } while (__builtin_amdgcn_is_invocable(__builtin_amdgcn_global_load_tr_b64_i32));
+
+ for (; __builtin_amdgcn_is_invocable(__builtin_amdgcn_permlane64); ++*p) break;
+
+**Description**:
+
+When used as the predicate value of the following control structures:
+
+.. code-block:: c++
+
+ if (...)
+ while (...)
+ do { } while (...)
+ for (...)
+
+be it directly, or as arguments to logical operators such as ``!, ||, &&``, the
+builtins return a boolean value that:
+
+* indicates whether the current target matches the argument; the argument MUST
+ be a string literal and a valid AMDGPU target
+* indicates whether the builtin function passed as the argument can be invoked
+ by the current target; the argument MUST be either a generic or AMDGPU
+ specific builtin name
+
+Outside of these contexts, the builtins have a ``void`` returning signature
+which prevents their misuse.
+
+**Example of invalid use**:
+
+.. code-block:: c++
+
+ void kernel(int* p, int x, bool (*pfn)(bool), const char* str) {
+ if (__builtin_amdgcn_processor_is("not_an_amdgcn_gfx_id")) return;
+ else if (__builtin_amdgcn_processor_is(str)) __builtin_trap();
+
+ bool a = __builtin_amdgcn_processor_is("gfx906");
+ const bool b = !__builtin_amdgcn_processor_is("gfx906");
+ const bool c = !__builtin_amdgcn_processor_is("gfx906");
+ bool d = __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ bool e = !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ const auto f =
+ !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready)
+ || __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ const auto g =
+ !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready)
+ || !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ __builtin_amdgcn_processor_is("gfx1201")
+ ? __builtin_amdgcn_s_sleep_var(x) : __builtin_amdgcn_s_sleep(42);
+ if (pfn(__builtin_amdgcn_processor_is("gfx1200")))
+ __builtin_amdgcn_s_sleep_var(x);
+
+ if (__builtin_amdgcn_is_invocable("__builtin_amdgcn_s_sleep_var")) return;
+ else if (__builtin_amdgcn_is_invocable(x)) __builtin_trap();
+ }
+
+When invoked while compiling for a concrete target, the builtins are evaluated
+early by Clang, and never produce any CodeGen effects / have no observable
+side-effects in IR. Conversely, when compiling for AMDGCN flavoured SPIR-v,
+which is an abstract target, a series of predicate values are implicitly
+created. These predicates get resolved when finalizing the compilation process
+for a concrete target, and shall reflect the latter's identity and features.
+Thus, it is possible to author high-level code, in e.g. HIP, that is target
+adaptive in a dynamic fashion, contrary to macro based mechanisms.
ARM/AArch64 Language Extensions
-------------------------------
diff --git a/clang/include/clang/Basic/BuiltinsAMDGPU.def b/clang/include/clang/Basic/BuiltinsAMDGPU.def
index 44ef404aee72f..5d01a7e75f7e7 100644
--- a/clang/include/clang/Basic/BuiltinsAMDGPU.def
+++ b/clang/include/clang/Basic/BuiltinsAMDGPU.def
@@ -346,6 +346,11 @@ BUILTIN(__builtin_amdgcn_endpgm, "v", "nr")
BUILTIN(__builtin_amdgcn_get_fpenv, "WUi", "n")
BUILTIN(__builtin_amdgcn_set_fpenv, "vWUi", "n")
+// These are special FE only builtins intended for forwarding the requirements
+// to the ME.
+BUILTIN(__builtin_amdgcn_processor_is, "vcC*", "nctu")
+BUILTIN(__builtin_amdgcn_is_invocable, "v", "nctu")
+
//===----------------------------------------------------------------------===//
// R600-NI only builtins.
//===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 5e45482584946..45f0f9eb88e55 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -13054,4 +13054,14 @@ def err_acc_decl_for_routine
// AMDGCN builtins diagnostics
def err_amdgcn_global_load_lds_size_invalid_value : Error<"invalid size value">;
def note_amdgcn_global_load_lds_size_valid_value : Note<"size must be %select{1, 2, or 4|1, 2, 4, 12 or 16}0">;
+def err_amdgcn_processor_is_arg_not_literal
+ : Error<"the argument to __builtin_amdgcn_processor_is must be a string "
+ "literal">;
+def err_amdgcn_processor_is_arg_invalid_value
+ : Error<"the argument to __builtin_amdgcn_processor_is must be a valid "
+ "AMDGCN processor identifier; '%0' is not valid">;
+def err_amdgcn_is_invocable_arg_invalid_value
+ : Error<"the argument to __builtin_amdgcn_is_invocable must be either a "
+ "target agnostic builtin or an AMDGCN target specific builtin; `%0`"
+ " is not valid">;
} // end of sema component.
diff --git a/clang/lib/Basic/Targets/SPIR.cpp b/clang/lib/Basic/Targets/SPIR.cpp
index 5b5f47f9647a2..eb43d9b0be283 100644
--- a/clang/lib/Basic/Targets/SPIR.cpp
+++ b/clang/lib/Basic/Targets/SPIR.cpp
@@ -152,3 +152,7 @@ void SPIRV64AMDGCNTargetInfo::setAuxTarget(const TargetInfo *Aux) {
Float128Format = DoubleFormat;
}
}
+
+bool SPIRV64AMDGCNTargetInfo::isValidCPUName(StringRef CPU) const {
+ return AMDGPUTI.isValidCPUName(CPU);
+}
diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
index 78505d66d6f2f..7aa13cbeb89fd 100644
--- a/clang/lib/Basic/Targets/SPIR.h
+++ b/clang/lib/Basic/Targets/SPIR.h
@@ -432,6 +432,10 @@ class LLVM_LIBRARY_VISIBILITY SPIRV64AMDGCNTargetInfo final
}
bool hasInt128Type() const override { return TargetInfo::hasInt128Type(); }
+
+ // This is only needed for validating arguments passed to
+ // __builtin_amdgcn_processor_is
+ bool isValidCPUName(StringRef Name) const override;
};
} // namespace targets
diff --git a/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp b/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
index b56b739094ff3..7b1a3815144b4 100644
--- a/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
@@ -284,6 +284,18 @@ void CodeGenFunction::AddAMDGPUFenceAddressSpaceMMRA(llvm::Instruction *Inst,
Inst->setMetadata(LLVMContext::MD_mmra, MMRAMetadata::getMD(Ctx, MMRAs));
}
+static Value *GetOrInsertAMDGPUPredicate(CodeGenFunction &CGF, Twine Name) {
+ auto PTy = IntegerType::getInt1Ty(CGF.getLLVMContext());
+
+ auto P = cast<GlobalVariable>(
+ CGF.CGM.getModule().getOrInsertGlobal(Name.str(), PTy));
+ P->setConstant(true);
+ P->setExternallyInitialized(true);
+
+ return CGF.Builder.CreateLoad(RawAddress(P, PTy, CharUnits::One(),
+ KnownNonNull));
+}
+
Value *CodeGenFunction::EmitAMDGPUBuiltinExpr(unsigned BuiltinID,
const CallExpr *E) {
llvm::AtomicOrdering AO = llvm::AtomicOrdering::SequentiallyConsistent;
@@ -585,6 +597,23 @@ Value *CodeGenFunction::EmitAMDGPUBuiltinExpr(unsigned BuiltinID,
llvm::Value *Env = EmitScalarExpr(E->getArg(0));
return Builder.CreateCall(F, {Env});
}
+ case AMDGPU::BI__builtin_amdgcn_processor_is: {
+ assert(CGM.getTriple().isSPIRV() &&
+ "__builtin_amdgcn_processor_is should never reach CodeGen for "
+ "concrete targets!");
+ StringRef Proc = cast<clang::StringLiteral>(E->getArg(0))->getString();
+ return GetOrInsertAMDGPUPredicate(*this, "llvm.amdgcn.is." + Proc);
+ }
+ case AMDGPU::BI__builtin_amdgcn_is_invocable: {
+ assert(CGM.getTriple().isSPIRV() &&
+ "__builtin_amdgcn_is_invocable should never reach CodeGen for "
+ "concrete targets!");
+ auto FD = cast<FunctionDecl>(
+ cast<DeclRefExpr>(E->getArg(0))->getReferencedDeclOfCallee());
+ StringRef RF =
+ getContext().BuiltinInfo.getRequiredFeatures(FD->getBuiltinID());
+ return GetOrInsertAMDGPUPredicate(*this, "llvm.amdgcn.has." + RF);
+ }
case AMDGPU::BI__builtin_amdgcn_read_exec:
return EmitAMDGCNBallotForExec(*this, E, Int64Ty, Int64Ty, false);
case AMDGPU::BI__builtin_amdgcn_read_exec_lo:
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 7cc8374e69d73..24f5262ab3cf4 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6541,6 +6541,22 @@ ExprResult Sema::BuildCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
if (Result.isInvalid()) return ExprError();
Fn = Result.get();
+ // The __builtin_amdgcn_is_invocable builtin is special, and will be resolved
+ // later, when we check boolean conditions, for now we merely forward it
+ // without any additional checking.
+ if (Fn->getType() == Context.BuiltinFnTy && ArgExprs.size() == 1 &&
+ ArgExprs[0]->getType() == Context.BuiltinFnTy) {
+ auto FD = cast<FunctionDecl>(Fn->getReferencedDeclOfCallee());
+
+ if (FD->getName() == "__builtin_amdgcn_is_invocable") {
+ auto FnPtrTy = Context.getPointerType(FD->getType());
+ auto R = ImpCastExprToType(Fn, FnPtrTy, CK_BuiltinFnToFnPtr).get();
+ return CallExpr::Create(Context, R, ArgExprs, Context.VoidTy,
+ ExprValueKind::VK_PRValue, RParenLoc,
+ FPOptionsOverride());
+ }
+ }
+
if (CheckArgsForPlaceholders(ArgExprs))
return ExprError();
@@ -13234,6 +13250,20 @@ inline QualType Sema::CheckBitwiseOperands(ExprResult &LHS, ExprResult &RHS,
return InvalidOperands(Loc, LHS, RHS);
}
+static inline bool IsAMDGPUPredicateBI(Expr *E) {
+ if (!E->getType()->isVoidType())
+ return false;
+
+ if (auto CE = dyn_cast<CallExpr>(E)) {
+ if (auto BI = CE->getDirectCallee())
+ if (BI->getName() == "__builtin_amdgcn_processor_is" ||
+ BI->getName() == "__builtin_amdgcn_is_invocable")
+ return true;
+ }
+
+ return false;
+}
+
// C99 6.5.[13,14]
inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
SourceLocation Loc,
@@ -13329,6 +13359,9 @@ inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
// The following is safe because we only use this method for
// non-overloadable operands.
+ if (IsAMDGPUPredicateBI(LHS.get()) && IsAMDGPUPredicateBI(RHS.get()))
+ return Context.VoidTy;
+
// C++ [expr.log.and]p1
// C++ [expr.log.or]p1
// The operands are both contextually converted to type bool.
@@ -15576,6 +15609,38 @@ static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) {
return Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy);
}
+static Expr *ExpandAMDGPUPredicateBI(ASTContext &Ctx, CallExpr *CE) {
+ if (!CE->getBuiltinCallee())
+ return CXXBoolLiteralExpr::Create(Ctx, false, Ctx.BoolTy, CE->getExprLoc());
+
+ if (Ctx.getTargetInfo().getTriple().isSPIRV()) {
+ CE->setType(Ctx.getLogicalOperationType());
+ return CE;
+ }
+
+ bool P = false;
+ auto &TI = Ctx.getTargetInfo();
+
+ if (CE->getDirectCallee()->getName() == "__builtin_amdgcn_processor_is") {
+ auto GFX = dyn_cast<StringLiteral>(CE->getArg(0)->IgnoreParenCasts());
+ auto TID = TI.getTargetID();
+ if (GFX && TID) {
+ auto N = GFX->getString();
+ P = TI.isValidCPUName(GFX->getString()) && TID->find(N) == 0;
+ }
+ } else {
+ auto FD = cast<FunctionDecl>(CE->getArg(0)->getReferencedDeclOfCallee());
+
+ StringRef RF = Ctx.BuiltinInfo.getRequiredFeatures(FD->getBuiltinID());
+ llvm::StringMap<bool> CF;
+ Ctx.getFunctionFeatureMap(CF, FD);
+
+ P = Builtin::evaluateRequiredTargetFeatures(RF, CF);
+ }
+
+ return CXXBoolLiteralExpr::Create(Ctx, P, Ctx.BoolTy, CE->getExprLoc());
+}
+
ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
UnaryOperatorKind Opc, Expr *InputExpr,
bool IsAfterAmp) {
@@ -15753,6 +15818,8 @@ ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
// Vector logical not returns the signed variant of the operand type.
resultType = GetSignedVectorType(resultType);
break;
+ } else if (IsAMDGPUPredicateBI(InputExpr)) {
+ break;
} else {
return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
<< resultType << Input.get()->getSourceRange());
@@ -20469,6 +20536,88 @@ void Sema::DiagnoseEqualityWithExtraParens(ParenExpr *ParenE) {
}
}
+static bool ValidateAMDGPUPredicateBI(Sema &Sema, CallExpr *CE) {
+ if (CE->getDirectCallee()->getName() == "__builtin_amdgcn_processor_is") {
+ auto GFX = dyn_cast<StringLiteral>(CE->getArg(0)->IgnoreParenCasts());
+ if (!GFX) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_processor_is_arg_not_literal);
+ return false;
+ }
+ auto N = GFX->getString();
+ if (!Sema.getASTContext().getTargetInfo().isValidCPUName(N) &&
+ (!Sema.getASTContext().getAuxTargetInfo() ||
+ !Sema.getASTContext().getAuxTargetInfo()->isValidCPUName(N))) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_processor_is_arg_invalid_value) << N;
+ return false;
+ }
+ } else {
+ auto Arg = CE->getArg(0);
+ if (!Arg || Arg->getType() != Sema.getASTContext().BuiltinFnTy) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_is_invocable_arg_invalid_value) << Arg;
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static Expr *MaybeHandleAMDGPUPredicateBI(Sema &Sema, Expr *E, bool &Invalid) {
+ if (auto UO = dyn_cast<UnaryOperator>(E)) {
+ auto SE = dyn_cast<CallExpr>(UO->getSubExpr());
+ if (IsAMDGPUPredicateBI(SE)) {
+ assert(
+ UO->getOpcode() == UnaryOperator::Opcode::UO_LNot &&
+ "__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable "
+ "can only be used as operands of logical ops!");
+
+ if (!ValidateAMDGPUPredicateBI(Sema, SE)) {
+ Invalid = true;
+ return nullptr;
+ }
+
+ UO->setSubExpr(ExpandAMDGPUPredicateBI(Sema.getASTContext(), SE));
+ UO->setType(Sema.getASTContext().getLogicalOperationType());
+
+ return UO;
+ }
+ }
+ if (auto BO = dyn_cast<BinaryOperator>(E)) {
+ auto LHS = dyn_cast<CallExpr>(BO->getLHS());
+ auto RHS = dyn_cast<CallExpr>(BO->getRHS());
+ if (IsAMDGPUPredicateBI(LHS) && IsAMDGPUPredicateBI(RHS)) {
+ assert(
+ BO->isLogicalOp() &&
+ "__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable "
+ "can only be used as operands of logical ops!");
+
+ if (!ValidateAMDGPUPredicateBI(Sema, LHS) ||
+ !ValidateAMDGPUPredicateBI(Sema, RHS)) {
+ Invalid = true;
+ return nullptr;
+ }
+
+ BO->setLHS(ExpandAMDGPUPredicateBI(Sema.getASTContext(), LHS));
+ BO->setRHS(ExpandAMDGPUPredicateBI(Sema.getASTContext(), RHS));
+ BO->setType(Sema.getASTContext().getLogicalOperationType());
+
+ return BO;
+ }
+ }
+ if (auto CE = dyn_cast<CallExpr>(E))
+ if (IsAMDGPUPredicateBI(CE)) {
+ if (!ValidateAMDGPUPredicateBI(Sema, CE)) {
+ Invalid = true;
+ return nullptr;
+ }
+ return ExpandAMDGPUPredicateBI(Sema.getASTContext(), CE);
+ }
+
+ return nullptr;
+}
+
ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
bool IsConstexpr) {
DiagnoseAssignmentAsCondition(E);
@@ -20480,6 +20629,14 @@ ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
E = result.get();
if (!E->isTypeDependent()) {
+ if (E->getType()->isVoidType()) {
+ bool IsInvalidPredicate = false;
+ if (auto BIC = MaybeHandleAMDGPUPredicateBI(*this, E, IsInvalidPredicate))
+ return BIC;
+ else if (IsInvalidPredicate)
+ return ExprError();
+ }
+
if (getLangOpts().CPlusPlus)
return CheckCXXBooleanCondition(E, IsConstexpr); // C++ 6.4p4
diff --git a/clang/test/CodeGen/amdgpu-builtin-cpu-is.c b/clang/test/CodeGen/amdgpu-builtin-cpu-is.c
new file mode 100644
index 0000000000000..6e261d9f5d239
--- /dev/null
+++ b/clang/test/CodeGen/amdgpu-builtin-cpu-is.c
@@ -0,0 +1,65 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --check-globals all --version 5
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCN-GFX900 %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx1010 -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCN-GFX1010 %s
+// RUN: %clang_cc1 -triple spirv64-amd-amdhsa -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCNSPIRV %s
+
+// Test that, depending on triple and, if applicable, target-cpu, one of three
+// things happens:
+// 1) for gfx900 we emit a call to trap (concrete target, matches)
+// 2) for gfx1010 we emit an empty kernel (concrete target, does not match)
+// 3) for AMDGCNSPIRV we emit llvm.amdgcn.is.gfx900 as a bool global, and
+// load from it to provide the condition a br (abstract target)
+//.
+// AMDGCN-GFX900: @__oclc_ABI_version = weak_odr hidden local_unnamed_addr addrspace(4) constant i32 600
+//.
+// AMDGCN-GFX1010: @__oclc_ABI_version = weak_odr hidden local_unnamed_addr addrspace(4) constant i32 600
+//.
+// AMDGCNSPIRV: @llvm.amdgcn.is.gfx900 = external addrspace(1) externally_initialized constant i1
+//.
+// AMDGCN-GFX900-LABEL: define dso_local void @foo(
+// AMDGCN-GFX900-SAME: ) #[[ATTR0:[0-9]+]] {
+// AMDGCN-GFX900-NEXT: [[ENTRY:.*:]]
+// AMDGCN-GFX900-NEXT: call void @llvm.trap()
+// AMDGCN-GFX900-NEXT: ret void
+//
+// AMDGCN-GFX1010-LABEL: define dso_local void @foo(
+// AMDGCN-GFX1010-SAME: ) #[[ATTR0:[0-9]+]] {
+// AMDGCN-GFX1010-NEXT: [[ENTRY:.*:]]
+// AMDGCN-GFX1010-NEXT: ret void
+//
+// AMDGCNSPIRV-LABEL: define spir_func void @foo(
+// AMDGCNSPIRV-SAME: ) addrspace(4) #[[ATTR0:[0-9]+]] {
+// AMDGCNSPIRV-NEXT: [[ENTRY:.*:]]
+// AMDGCNSPIRV-NEXT: [[TMP0:%.*]] = load i1, ptr addrspace(1) @llvm.amdgcn.is.gfx900, align 1
+// AMDGCNSPIRV-NEXT: br i1 [[TMP0]], label %[[IF_THEN:.*]], label %[[IF_END:.*]]
+// AMDGCNSPIRV: [[IF_THEN]]:
+// AMDGCNSPIRV-NEXT: call addrspace(4) void @llvm.trap()
+// AMDGCNSPIRV-NEXT: br label %[[IF_END]]
+// AMDGCNSPIRV: [[IF_END]]:
+// AMDGCNSPIRV-NEXT: ret void
+//
+void foo() {
+ if (__builtin_cpu_is("gfx90...
[truncated]
|
|
@llvm/pr-subscribers-clang-codegen Author: Alex Voicu (AlexVlx) ChangesThis change adds two semi-magical builtins for AMDGPU:
Neither of these are The motivation for adding these is two-fold:
I've tried to keep the overall footprint of the change small. The changes to Sema are a bit unpleasant, but there was a strong desire to have Clang validate these, and to constrain their uses, and this was the most compact solution I could come up with (suggestions welcome). In the end, I will note there is nothing that is actually AMDGPU specific here, so it is possible that in the future, assuming interests from other targets / users, we'd just promote them to generic intrinsics. Patch is 59.55 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/134016.diff 17 Files Affected:
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 3b8a9cac6587a..8a7cb75af13e5 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -4920,6 +4920,116 @@ If no address spaces names are provided, all address spaces are fenced.
__builtin_amdgcn_fence(__ATOMIC_SEQ_CST, "workgroup", "local")
__builtin_amdgcn_fence(__ATOMIC_SEQ_CST, "workgroup", "local", "global")
+__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+``__builtin_amdgcn_processor_is`` and ``__builtin_amdgcn_is_invocable`` provide
+a functional mechanism for programatically querying:
+
+* the identity of the current target processor;
+* the capability of the current target processor to invoke a particular builtin.
+
+**Syntax**:
+
+.. code-block:: c
+
+ // When used as the predicate for a control structure
+ bool __builtin_amdgcn_processor_is(const char*);
+ bool __builtin_amdgcn_is_invocable(builtin_name);
+ // Otherwise
+ void __builtin_amdgcn_processor_is(const char*);
+ void __builtin_amdgcn_is_invocable(void);
+
+**Example of use**:
+
+.. code-block:: c++
+
+ if (__builtin_amdgcn_processor_is("gfx1201") ||
+ __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var))
+ __builtin_amdgcn_s_sleep_var(x);
+
+ if (!__builtin_amdgcn_processor_is("gfx906"))
+ __builtin_amdgcn_s_wait_event_export_ready();
+ else if (__builtin_amdgcn_processor_is("gfx1010") ||
+ __builtin_amdgcn_processor_is("gfx1101"))
+ __builtin_amdgcn_s_ttracedata_imm(1);
+
+ while (__builtin_amdgcn_processor_is("gfx1101")) *p += x;
+
+ do { *p -= x; } while (__builtin_amdgcn_processor_is("gfx1010"));
+
+ for (; __builtin_amdgcn_processor_is("gfx1201"); ++*p) break;
+
+ if (__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready))
+ __builtin_amdgcn_s_wait_event_export_ready();
+ else if (__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_ttracedata_imm))
+ __builtin_amdgcn_s_ttracedata_imm(1);
+
+ do {
+ *p -= x;
+ } while (__builtin_amdgcn_is_invocable(__builtin_amdgcn_global_load_tr_b64_i32));
+
+ for (; __builtin_amdgcn_is_invocable(__builtin_amdgcn_permlane64); ++*p) break;
+
+**Description**:
+
+When used as the predicate value of the following control structures:
+
+.. code-block:: c++
+
+ if (...)
+ while (...)
+ do { } while (...)
+ for (...)
+
+be it directly, or as arguments to logical operators such as ``!, ||, &&``, the
+builtins return a boolean value that:
+
+* indicates whether the current target matches the argument; the argument MUST
+ be a string literal and a valid AMDGPU target
+* indicates whether the builtin function passed as the argument can be invoked
+ by the current target; the argument MUST be either a generic or AMDGPU
+ specific builtin name
+
+Outside of these contexts, the builtins have a ``void`` returning signature
+which prevents their misuse.
+
+**Example of invalid use**:
+
+.. code-block:: c++
+
+ void kernel(int* p, int x, bool (*pfn)(bool), const char* str) {
+ if (__builtin_amdgcn_processor_is("not_an_amdgcn_gfx_id")) return;
+ else if (__builtin_amdgcn_processor_is(str)) __builtin_trap();
+
+ bool a = __builtin_amdgcn_processor_is("gfx906");
+ const bool b = !__builtin_amdgcn_processor_is("gfx906");
+ const bool c = !__builtin_amdgcn_processor_is("gfx906");
+ bool d = __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ bool e = !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ const auto f =
+ !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready)
+ || __builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ const auto g =
+ !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_wait_event_export_ready)
+ || !__builtin_amdgcn_is_invocable(__builtin_amdgcn_s_sleep_var);
+ __builtin_amdgcn_processor_is("gfx1201")
+ ? __builtin_amdgcn_s_sleep_var(x) : __builtin_amdgcn_s_sleep(42);
+ if (pfn(__builtin_amdgcn_processor_is("gfx1200")))
+ __builtin_amdgcn_s_sleep_var(x);
+
+ if (__builtin_amdgcn_is_invocable("__builtin_amdgcn_s_sleep_var")) return;
+ else if (__builtin_amdgcn_is_invocable(x)) __builtin_trap();
+ }
+
+When invoked while compiling for a concrete target, the builtins are evaluated
+early by Clang, and never produce any CodeGen effects / have no observable
+side-effects in IR. Conversely, when compiling for AMDGCN flavoured SPIR-v,
+which is an abstract target, a series of predicate values are implicitly
+created. These predicates get resolved when finalizing the compilation process
+for a concrete target, and shall reflect the latter's identity and features.
+Thus, it is possible to author high-level code, in e.g. HIP, that is target
+adaptive in a dynamic fashion, contrary to macro based mechanisms.
ARM/AArch64 Language Extensions
-------------------------------
diff --git a/clang/include/clang/Basic/BuiltinsAMDGPU.def b/clang/include/clang/Basic/BuiltinsAMDGPU.def
index 44ef404aee72f..5d01a7e75f7e7 100644
--- a/clang/include/clang/Basic/BuiltinsAMDGPU.def
+++ b/clang/include/clang/Basic/BuiltinsAMDGPU.def
@@ -346,6 +346,11 @@ BUILTIN(__builtin_amdgcn_endpgm, "v", "nr")
BUILTIN(__builtin_amdgcn_get_fpenv, "WUi", "n")
BUILTIN(__builtin_amdgcn_set_fpenv, "vWUi", "n")
+// These are special FE only builtins intended for forwarding the requirements
+// to the ME.
+BUILTIN(__builtin_amdgcn_processor_is, "vcC*", "nctu")
+BUILTIN(__builtin_amdgcn_is_invocable, "v", "nctu")
+
//===----------------------------------------------------------------------===//
// R600-NI only builtins.
//===----------------------------------------------------------------------===//
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 5e45482584946..45f0f9eb88e55 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -13054,4 +13054,14 @@ def err_acc_decl_for_routine
// AMDGCN builtins diagnostics
def err_amdgcn_global_load_lds_size_invalid_value : Error<"invalid size value">;
def note_amdgcn_global_load_lds_size_valid_value : Note<"size must be %select{1, 2, or 4|1, 2, 4, 12 or 16}0">;
+def err_amdgcn_processor_is_arg_not_literal
+ : Error<"the argument to __builtin_amdgcn_processor_is must be a string "
+ "literal">;
+def err_amdgcn_processor_is_arg_invalid_value
+ : Error<"the argument to __builtin_amdgcn_processor_is must be a valid "
+ "AMDGCN processor identifier; '%0' is not valid">;
+def err_amdgcn_is_invocable_arg_invalid_value
+ : Error<"the argument to __builtin_amdgcn_is_invocable must be either a "
+ "target agnostic builtin or an AMDGCN target specific builtin; `%0`"
+ " is not valid">;
} // end of sema component.
diff --git a/clang/lib/Basic/Targets/SPIR.cpp b/clang/lib/Basic/Targets/SPIR.cpp
index 5b5f47f9647a2..eb43d9b0be283 100644
--- a/clang/lib/Basic/Targets/SPIR.cpp
+++ b/clang/lib/Basic/Targets/SPIR.cpp
@@ -152,3 +152,7 @@ void SPIRV64AMDGCNTargetInfo::setAuxTarget(const TargetInfo *Aux) {
Float128Format = DoubleFormat;
}
}
+
+bool SPIRV64AMDGCNTargetInfo::isValidCPUName(StringRef CPU) const {
+ return AMDGPUTI.isValidCPUName(CPU);
+}
diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
index 78505d66d6f2f..7aa13cbeb89fd 100644
--- a/clang/lib/Basic/Targets/SPIR.h
+++ b/clang/lib/Basic/Targets/SPIR.h
@@ -432,6 +432,10 @@ class LLVM_LIBRARY_VISIBILITY SPIRV64AMDGCNTargetInfo final
}
bool hasInt128Type() const override { return TargetInfo::hasInt128Type(); }
+
+ // This is only needed for validating arguments passed to
+ // __builtin_amdgcn_processor_is
+ bool isValidCPUName(StringRef Name) const override;
};
} // namespace targets
diff --git a/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp b/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
index b56b739094ff3..7b1a3815144b4 100644
--- a/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
@@ -284,6 +284,18 @@ void CodeGenFunction::AddAMDGPUFenceAddressSpaceMMRA(llvm::Instruction *Inst,
Inst->setMetadata(LLVMContext::MD_mmra, MMRAMetadata::getMD(Ctx, MMRAs));
}
+static Value *GetOrInsertAMDGPUPredicate(CodeGenFunction &CGF, Twine Name) {
+ auto PTy = IntegerType::getInt1Ty(CGF.getLLVMContext());
+
+ auto P = cast<GlobalVariable>(
+ CGF.CGM.getModule().getOrInsertGlobal(Name.str(), PTy));
+ P->setConstant(true);
+ P->setExternallyInitialized(true);
+
+ return CGF.Builder.CreateLoad(RawAddress(P, PTy, CharUnits::One(),
+ KnownNonNull));
+}
+
Value *CodeGenFunction::EmitAMDGPUBuiltinExpr(unsigned BuiltinID,
const CallExpr *E) {
llvm::AtomicOrdering AO = llvm::AtomicOrdering::SequentiallyConsistent;
@@ -585,6 +597,23 @@ Value *CodeGenFunction::EmitAMDGPUBuiltinExpr(unsigned BuiltinID,
llvm::Value *Env = EmitScalarExpr(E->getArg(0));
return Builder.CreateCall(F, {Env});
}
+ case AMDGPU::BI__builtin_amdgcn_processor_is: {
+ assert(CGM.getTriple().isSPIRV() &&
+ "__builtin_amdgcn_processor_is should never reach CodeGen for "
+ "concrete targets!");
+ StringRef Proc = cast<clang::StringLiteral>(E->getArg(0))->getString();
+ return GetOrInsertAMDGPUPredicate(*this, "llvm.amdgcn.is." + Proc);
+ }
+ case AMDGPU::BI__builtin_amdgcn_is_invocable: {
+ assert(CGM.getTriple().isSPIRV() &&
+ "__builtin_amdgcn_is_invocable should never reach CodeGen for "
+ "concrete targets!");
+ auto FD = cast<FunctionDecl>(
+ cast<DeclRefExpr>(E->getArg(0))->getReferencedDeclOfCallee());
+ StringRef RF =
+ getContext().BuiltinInfo.getRequiredFeatures(FD->getBuiltinID());
+ return GetOrInsertAMDGPUPredicate(*this, "llvm.amdgcn.has." + RF);
+ }
case AMDGPU::BI__builtin_amdgcn_read_exec:
return EmitAMDGCNBallotForExec(*this, E, Int64Ty, Int64Ty, false);
case AMDGPU::BI__builtin_amdgcn_read_exec_lo:
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 7cc8374e69d73..24f5262ab3cf4 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6541,6 +6541,22 @@ ExprResult Sema::BuildCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
if (Result.isInvalid()) return ExprError();
Fn = Result.get();
+ // The __builtin_amdgcn_is_invocable builtin is special, and will be resolved
+ // later, when we check boolean conditions, for now we merely forward it
+ // without any additional checking.
+ if (Fn->getType() == Context.BuiltinFnTy && ArgExprs.size() == 1 &&
+ ArgExprs[0]->getType() == Context.BuiltinFnTy) {
+ auto FD = cast<FunctionDecl>(Fn->getReferencedDeclOfCallee());
+
+ if (FD->getName() == "__builtin_amdgcn_is_invocable") {
+ auto FnPtrTy = Context.getPointerType(FD->getType());
+ auto R = ImpCastExprToType(Fn, FnPtrTy, CK_BuiltinFnToFnPtr).get();
+ return CallExpr::Create(Context, R, ArgExprs, Context.VoidTy,
+ ExprValueKind::VK_PRValue, RParenLoc,
+ FPOptionsOverride());
+ }
+ }
+
if (CheckArgsForPlaceholders(ArgExprs))
return ExprError();
@@ -13234,6 +13250,20 @@ inline QualType Sema::CheckBitwiseOperands(ExprResult &LHS, ExprResult &RHS,
return InvalidOperands(Loc, LHS, RHS);
}
+static inline bool IsAMDGPUPredicateBI(Expr *E) {
+ if (!E->getType()->isVoidType())
+ return false;
+
+ if (auto CE = dyn_cast<CallExpr>(E)) {
+ if (auto BI = CE->getDirectCallee())
+ if (BI->getName() == "__builtin_amdgcn_processor_is" ||
+ BI->getName() == "__builtin_amdgcn_is_invocable")
+ return true;
+ }
+
+ return false;
+}
+
// C99 6.5.[13,14]
inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
SourceLocation Loc,
@@ -13329,6 +13359,9 @@ inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
// The following is safe because we only use this method for
// non-overloadable operands.
+ if (IsAMDGPUPredicateBI(LHS.get()) && IsAMDGPUPredicateBI(RHS.get()))
+ return Context.VoidTy;
+
// C++ [expr.log.and]p1
// C++ [expr.log.or]p1
// The operands are both contextually converted to type bool.
@@ -15576,6 +15609,38 @@ static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) {
return Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy);
}
+static Expr *ExpandAMDGPUPredicateBI(ASTContext &Ctx, CallExpr *CE) {
+ if (!CE->getBuiltinCallee())
+ return CXXBoolLiteralExpr::Create(Ctx, false, Ctx.BoolTy, CE->getExprLoc());
+
+ if (Ctx.getTargetInfo().getTriple().isSPIRV()) {
+ CE->setType(Ctx.getLogicalOperationType());
+ return CE;
+ }
+
+ bool P = false;
+ auto &TI = Ctx.getTargetInfo();
+
+ if (CE->getDirectCallee()->getName() == "__builtin_amdgcn_processor_is") {
+ auto GFX = dyn_cast<StringLiteral>(CE->getArg(0)->IgnoreParenCasts());
+ auto TID = TI.getTargetID();
+ if (GFX && TID) {
+ auto N = GFX->getString();
+ P = TI.isValidCPUName(GFX->getString()) && TID->find(N) == 0;
+ }
+ } else {
+ auto FD = cast<FunctionDecl>(CE->getArg(0)->getReferencedDeclOfCallee());
+
+ StringRef RF = Ctx.BuiltinInfo.getRequiredFeatures(FD->getBuiltinID());
+ llvm::StringMap<bool> CF;
+ Ctx.getFunctionFeatureMap(CF, FD);
+
+ P = Builtin::evaluateRequiredTargetFeatures(RF, CF);
+ }
+
+ return CXXBoolLiteralExpr::Create(Ctx, P, Ctx.BoolTy, CE->getExprLoc());
+}
+
ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
UnaryOperatorKind Opc, Expr *InputExpr,
bool IsAfterAmp) {
@@ -15753,6 +15818,8 @@ ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
// Vector logical not returns the signed variant of the operand type.
resultType = GetSignedVectorType(resultType);
break;
+ } else if (IsAMDGPUPredicateBI(InputExpr)) {
+ break;
} else {
return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
<< resultType << Input.get()->getSourceRange());
@@ -20469,6 +20536,88 @@ void Sema::DiagnoseEqualityWithExtraParens(ParenExpr *ParenE) {
}
}
+static bool ValidateAMDGPUPredicateBI(Sema &Sema, CallExpr *CE) {
+ if (CE->getDirectCallee()->getName() == "__builtin_amdgcn_processor_is") {
+ auto GFX = dyn_cast<StringLiteral>(CE->getArg(0)->IgnoreParenCasts());
+ if (!GFX) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_processor_is_arg_not_literal);
+ return false;
+ }
+ auto N = GFX->getString();
+ if (!Sema.getASTContext().getTargetInfo().isValidCPUName(N) &&
+ (!Sema.getASTContext().getAuxTargetInfo() ||
+ !Sema.getASTContext().getAuxTargetInfo()->isValidCPUName(N))) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_processor_is_arg_invalid_value) << N;
+ return false;
+ }
+ } else {
+ auto Arg = CE->getArg(0);
+ if (!Arg || Arg->getType() != Sema.getASTContext().BuiltinFnTy) {
+ Sema.Diag(CE->getExprLoc(),
+ diag::err_amdgcn_is_invocable_arg_invalid_value) << Arg;
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static Expr *MaybeHandleAMDGPUPredicateBI(Sema &Sema, Expr *E, bool &Invalid) {
+ if (auto UO = dyn_cast<UnaryOperator>(E)) {
+ auto SE = dyn_cast<CallExpr>(UO->getSubExpr());
+ if (IsAMDGPUPredicateBI(SE)) {
+ assert(
+ UO->getOpcode() == UnaryOperator::Opcode::UO_LNot &&
+ "__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable "
+ "can only be used as operands of logical ops!");
+
+ if (!ValidateAMDGPUPredicateBI(Sema, SE)) {
+ Invalid = true;
+ return nullptr;
+ }
+
+ UO->setSubExpr(ExpandAMDGPUPredicateBI(Sema.getASTContext(), SE));
+ UO->setType(Sema.getASTContext().getLogicalOperationType());
+
+ return UO;
+ }
+ }
+ if (auto BO = dyn_cast<BinaryOperator>(E)) {
+ auto LHS = dyn_cast<CallExpr>(BO->getLHS());
+ auto RHS = dyn_cast<CallExpr>(BO->getRHS());
+ if (IsAMDGPUPredicateBI(LHS) && IsAMDGPUPredicateBI(RHS)) {
+ assert(
+ BO->isLogicalOp() &&
+ "__builtin_amdgcn_processor_is and __builtin_amdgcn_is_invocable "
+ "can only be used as operands of logical ops!");
+
+ if (!ValidateAMDGPUPredicateBI(Sema, LHS) ||
+ !ValidateAMDGPUPredicateBI(Sema, RHS)) {
+ Invalid = true;
+ return nullptr;
+ }
+
+ BO->setLHS(ExpandAMDGPUPredicateBI(Sema.getASTContext(), LHS));
+ BO->setRHS(ExpandAMDGPUPredicateBI(Sema.getASTContext(), RHS));
+ BO->setType(Sema.getASTContext().getLogicalOperationType());
+
+ return BO;
+ }
+ }
+ if (auto CE = dyn_cast<CallExpr>(E))
+ if (IsAMDGPUPredicateBI(CE)) {
+ if (!ValidateAMDGPUPredicateBI(Sema, CE)) {
+ Invalid = true;
+ return nullptr;
+ }
+ return ExpandAMDGPUPredicateBI(Sema.getASTContext(), CE);
+ }
+
+ return nullptr;
+}
+
ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
bool IsConstexpr) {
DiagnoseAssignmentAsCondition(E);
@@ -20480,6 +20629,14 @@ ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
E = result.get();
if (!E->isTypeDependent()) {
+ if (E->getType()->isVoidType()) {
+ bool IsInvalidPredicate = false;
+ if (auto BIC = MaybeHandleAMDGPUPredicateBI(*this, E, IsInvalidPredicate))
+ return BIC;
+ else if (IsInvalidPredicate)
+ return ExprError();
+ }
+
if (getLangOpts().CPlusPlus)
return CheckCXXBooleanCondition(E, IsConstexpr); // C++ 6.4p4
diff --git a/clang/test/CodeGen/amdgpu-builtin-cpu-is.c b/clang/test/CodeGen/amdgpu-builtin-cpu-is.c
new file mode 100644
index 0000000000000..6e261d9f5d239
--- /dev/null
+++ b/clang/test/CodeGen/amdgpu-builtin-cpu-is.c
@@ -0,0 +1,65 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --check-globals all --version 5
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCN-GFX900 %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx1010 -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCN-GFX1010 %s
+// RUN: %clang_cc1 -triple spirv64-amd-amdhsa -emit-llvm %s -o - | FileCheck --check-prefix=AMDGCNSPIRV %s
+
+// Test that, depending on triple and, if applicable, target-cpu, one of three
+// things happens:
+// 1) for gfx900 we emit a call to trap (concrete target, matches)
+// 2) for gfx1010 we emit an empty kernel (concrete target, does not match)
+// 3) for AMDGCNSPIRV we emit llvm.amdgcn.is.gfx900 as a bool global, and
+// load from it to provide the condition a br (abstract target)
+//.
+// AMDGCN-GFX900: @__oclc_ABI_version = weak_odr hidden local_unnamed_addr addrspace(4) constant i32 600
+//.
+// AMDGCN-GFX1010: @__oclc_ABI_version = weak_odr hidden local_unnamed_addr addrspace(4) constant i32 600
+//.
+// AMDGCNSPIRV: @llvm.amdgcn.is.gfx900 = external addrspace(1) externally_initialized constant i1
+//.
+// AMDGCN-GFX900-LABEL: define dso_local void @foo(
+// AMDGCN-GFX900-SAME: ) #[[ATTR0:[0-9]+]] {
+// AMDGCN-GFX900-NEXT: [[ENTRY:.*:]]
+// AMDGCN-GFX900-NEXT: call void @llvm.trap()
+// AMDGCN-GFX900-NEXT: ret void
+//
+// AMDGCN-GFX1010-LABEL: define dso_local void @foo(
+// AMDGCN-GFX1010-SAME: ) #[[ATTR0:[0-9]+]] {
+// AMDGCN-GFX1010-NEXT: [[ENTRY:.*:]]
+// AMDGCN-GFX1010-NEXT: ret void
+//
+// AMDGCNSPIRV-LABEL: define spir_func void @foo(
+// AMDGCNSPIRV-SAME: ) addrspace(4) #[[ATTR0:[0-9]+]] {
+// AMDGCNSPIRV-NEXT: [[ENTRY:.*:]]
+// AMDGCNSPIRV-NEXT: [[TMP0:%.*]] = load i1, ptr addrspace(1) @llvm.amdgcn.is.gfx900, align 1
+// AMDGCNSPIRV-NEXT: br i1 [[TMP0]], label %[[IF_THEN:.*]], label %[[IF_END:.*]]
+// AMDGCNSPIRV: [[IF_THEN]]:
+// AMDGCNSPIRV-NEXT: call addrspace(4) void @llvm.trap()
+// AMDGCNSPIRV-NEXT: br label %[[IF_END]]
+// AMDGCNSPIRV: [[IF_END]]:
+// AMDGCNSPIRV-NEXT: ret void
+//
+void foo() {
+ if (__builtin_cpu_is("gfx90...
[truncated]
|
AlexVlx
added
SPIR-V
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
llvmbot
added
clang
jhuber6
reviewed
Apr 2, 2025
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Very cool, in general I'm a fan of being able to use LLVM-IR as a more general target. We already hack around these things in practice, so I think it's only beneficial to formalize is in a more correct way, even if LLVM-IR wasn't 'strictly' intended to be this kind of serialization format.
| // AMDGCNSPIRV-NEXT: ret void | ||
| // | ||
| void foo() { | ||
| if (__builtin_amdgcn_is_invocable(__builtin_amdgcn_permlanex16)) |
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Is this intended to handle builtins that require certain target features to be set?
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Could we get a test? Something simple like +dpp?
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Could we get a test? Something simple like
+dpp?
Sure, but if possible, could you clarify what you would like to be tested / what you expect to see, so that we avoid churning.
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The issue with how the ROCm device libs does it, is that certain builtins require target features to be used. It hacks around this with the __attribute__((target)). I just want to know that you can call a builtin that requires +ddp features without that.
shiltian
reviewed
Apr 2, 2025
Indeed! I botched moving the changes from my internal scratchpad, and the rel notes got lost; fixing. |
AlexVlx
commented
May 7, 2025
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A side question, is it legal to use the builtin in unstructured control flow, like here: https://godbolt.org/z/no7Kzv19r ? Note, if the answer is "no", then enforcing the builtin to initialize something would (probably) automatically prevent this case, as clang would error out with:
error: cannot jump from this goto statement to its label note: jump bypasses variable initialization
Many thanks for asking this, I had completely ignored this scenario! I've added handling for this which is symmetric with what we already do for if constexpr or if available; indeed, the answer to your question was "no":)
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@erichkeane @AaronBallman if, when you have time, you could please indicate if the new direction is at least generally aligned with what you had in mind, it'd be appreciated! |
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Gentle ping. |
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I think the proposed approach is a reasonable direction. WDYT @erichkeane ?
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| The builtins return a value of type ``__amdgpu_feature_predicate_t``, which is a | ||
| target specific type that behaves as if its C++ definition was the following: |
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Does this builtin work in C? If so, the docs should be updated to make it clear that this behavior applies to C as well as C++ and explain what it means in a bit more detail (presume that C users have no idea how C++ idioms work).
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Yes, it does work in C, although I'm not convinced it will see significant use. That being said, there's no good reason to make it C++ only. I have tried to add an explanation for that context / provide a fleshed out example, please do let me know if it's more or less aligned with what you had in mind. Thanks!
erichkeane
reviewed
May 16, 2025
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First, please take a look at the LLVM coding standard re the use of 'auto'.
Second: The use of a special type for these builtins is a little novel (though I see the predicate type already exists?), but I guess I'm ok with it. I have some concerns with how the conversions for it work, particularly being represented always as an i1, but the tests you have look about right.
I would like to see a test that is effectively:
bool f() {
return __builtin_amdgcn_processor_is(...);
}
(and maybe one returning 'auto' to make sure it is deduced properly).
clang/docs/ReleaseNotes.rst
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| @@ -758,6 +758,10 @@ AMDGPU Support | |||
| ^^^^^^^^^^^^^^ | |||
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| - Bump the default code object version to 6. ROCm 6.3 is required to run any program compiled with COV6. | |||
| - Introduced a new target specific builtin ``__builtin_amdgcn_processor_is``, | |||
| a late / deferred query for the current target processor | |||
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Suggested change
| a late / deferred query for the current target processor | |
| a late / deferred query for the current target processor. |
clang/docs/ReleaseNotes.rst
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| - Introduced a new target specific builtin ``__builtin_amdgcn_processor_is``, | ||
| a late / deferred query for the current target processor | ||
| - Introduced a new target specific builtin ``__builtin_amdgcn_is_invocable``, | ||
| which enables fine-grained, per-builtin, feature availability |
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Suggested change
| which enables fine-grained, per-builtin, feature availability | |
| which enables fine-grained, per-builtin, feature availability. |
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| /// Expand a valid use of the feature identification builtins into its | ||
| /// corresponding sequence of instructions. | ||
| Expr *ExpandAMDGPUPredicateBI(CallExpr *CE); |
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Suggested change
| Expr *ExpandAMDGPUPredicateBI(CallExpr *CE); | |
| Expr *ExpandAMDGPUPredicateBuiltIn(CallExpr *CE); |
clang/lib/Sema/SemaAMDGPU.cpp
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| @@ -366,4 +367,72 @@ void SemaAMDGPU::handleAMDGPUMaxNumWorkGroupsAttr(Decl *D, | |||
| addAMDGPUMaxNumWorkGroupsAttr(D, AL, AL.getArgAsExpr(0), YExpr, ZExpr); | |||
| } | |||
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| Expr *SemaAMDGPU::ExpandAMDGPUPredicateBI(CallExpr *CE) { | |||
| auto &Ctx = getASTContext(); | |||
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None of these are supposed to be 'auto' unless the type itself is on the RHS. Goes for most of this function.
clang/lib/Sema/SemaExpr.cpp
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| auto *FD = cast<FunctionDecl>(Fn->getReferencedDeclOfCallee()); | ||
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| if (FD->getName() == "__builtin_amdgcn_is_invocable") { | ||
| auto FnPtrTy = Context.getPointerType(FD->getType()); |
AlexVlx
commented
Jun 2, 2025
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First, please take a look at the LLVM coding standard re the use of 'auto'.
Second: The use of a special type for these builtins is a little novel (though I see the predicate type already exists?), but I guess I'm ok with it. I have some concerns with how the conversions for it work, particularly being represented always as an
i1, but the tests you have look about right.I would like to see a test that is effectively:
bool f() { return __builtin_amdgcn_processor_is(...); }(and maybe one returning 'auto' to make sure it is deduced properly).
Apologies, I missed this earlier, and only got around to adding them now. Please do note that for cases where the function return type is bool one cannot directly return a predicate value, as it does not get implicitly casted to bool. This matches the behaviour of a type with an explicit conversion operator, which is what we're modelling.
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This change adds two semi-magical builtins for AMDGPU:
__builtin_amdgcn_processor_is, which is similar in observable behaviour with__builtin_cpu_is, except that it is never "evaluated" at run time;__builtin_amdgcn_is_invocable, which is behaviourally similar with__has_builtin, except that it is not a macro (i.e. not evaluated at preprocessing time).Neither of these are
constexpr, even though when compiling for concrete (i.e.gfxXXX/gfxXXX-generic) targets they get evaluated in Clang, so they shouldn't tear the AST too badly / at all for multi-pass compilation cases like HIP. They can only be used in specific contexts (as args to control structures).The motivation for adding these is two-fold:
I've tried to keep the overall footprint of the change small. The changes to Sema are a bit unpleasant, but there was a strong desire to have Clang validate these, and to constrain their uses, and this was the most compact solution I could come up with (suggestions welcome).
In the end, I will note there is nothing that is actually AMDGPU specific here, so it is possible that in the future, assuming interests from other targets / users, we'd just promote them to generic intrinsics.