[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]
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@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
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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
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Apr 2, 2025
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This is worth a release note item.
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Indeed! I botched moving the changes from my internal scratchpad, and the rel notes got lost; fixing. |
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@efriedma-quic was kind enough to have a call where we discussed this a bit more. I'll update tomorrow with a potential way forward, for the group's consideration. |
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Following up, here's a possible approach to making progress, broken down in phases, (@efriedma-quic can correct me if I am misrepresenting any of these):
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The frontend tradeoffs here are complicated and already under discussion so I'm going to skip over that aspect. This looks like a layer of stuff which can be built on top of an llvm intrinsic that guarantees branch folding before instruction selection. The problems with the rocm device libs having invalid code on branches that the compiler is meant to strip but doesn't at O0 would be solvable by leaving calls to that raw intrinsic in place. We can probably do that as an intrinsic returning bool passed to the branch, where a target hook is called on it to resolve to true/false/report-error, as part of a simple simplify-cfg style pass. Essentially just force the evaluation of the intrinsic and then promise to delete dead branches. I'd like that intrinsic anyway for language runtime hackery. Is there an RFC associated with this that would be a better place to put that thought? If I implement it, are we game for rebasing this on said general purpose lowering intrinsic? |
…dgcn_is_invocable` as the solution.
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Gentle ping given that the above has been added, with the caveat that warning on unguarded ASM hasn't been added yet, and the diagnostics are conservative & optimistic (we assume that if a guard exists it is correct, and do not do a feature check). This will be addressed in a subsequent patch which builds on what is now there, because we need some additional internal discussion on the AMD-side around the shape of these diagnostics, and because it would add some more girth to what is already a pretty large change. |
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Gentle ping. |
jhuber6
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Aug 4, 2025
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This looks good for me as a first step, but we'll definitely need some of the others to chime in before merging. In general I'd like to see us move towards something that more generic, considering that it seems like SPIRV, NVPTX, and AMDGPU now all have differing opinions on how to solve this. It would be nice to have a common LLVM intrinsic for this.
nikic
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Aug 5, 2025
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Looks like this is still using magic globals rather than intrinsics.
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I replied to this a few days ago, but either I didn't press the right button or messed something else up, apologies. At any rate, yes, for now it is still using magic globals since we've had this working for some time internally and also for AMDGCN SPIR-V uses we can rely on pass ordering to ensure no optimisations muck things up. Unless you consider it crucial to switch to intrinsics from the get-go, I would rather postpone that for later, after adding the full-fat diagnostics, possibly as part of generalising the functionality to other targets, if they are interested. This is mostly to minimise risk / go with something that we know works (and piping intrinsics through SPIR-V is slightly more tricky), and because I'm rather certain we can do the switch transparently i.e. users of the feature wouldn't know anything happened. |
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I strongly oppose the magic globals approach despite rocm being enthusiastic users of it. I tracked down some of the authors of that to ask why there are IR files containing a single constant being linked in using llvm-link in the middle of clang and the best answer I got was that it seemed easier than creating the constant directly, which is nonsense. I want this feature. If we let it in with the magic globals that rocm loves, they'll stay forever, and people will fight us when we try to replace them with intrinsics because it's different to rocm, so in practice that hack lives forever and ever. The commit gate is the highest leverage point we have to not adopt that mistake. |
JonChesterfield
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Aug 11, 2025
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Request using intrinsics to represent this, not magic global variables, on the grounds that the magic globals hack should not have been done in the first place and definitely didn't need to live for a decade in rocm device libs.
Given how long it has existed there, I do not have confidence it would be fixed after commit in upstream. Further, I think someone else fixing it upstream would be opposed by the rocm developers on grounds of divergence from their fork.
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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.