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4be8a26951
Currently, when one or more attributes are mutually exclusive, the developer adding the attribute has to manually emit diagnostics. In practice, this is highly error prone, especially for declaration attributes, because such checking is not trivial. Redeclarations require you to write a "merge" function to diagnose mutually exclusive attributes and most attributes get this wrong. This patch introduces a table-generated way to specify that a group of two or more attributes are mutually exclusive: def : MutualExclusions<[Attr1, Attr2, Attr3]>; This works for both statement and declaration attributes (but not type attributes) and the checking is done either from the common attribute diagnostic checking code or from within mergeDeclAttribute() when merging redeclarations.
432 lines
16 KiB
C++
432 lines
16 KiB
C++
//===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements stmt-related attribute processing.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/EvaluatedExprVisitor.h"
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#include "clang/Basic/SourceManager.h"
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#include "clang/Basic/TargetInfo.h"
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#include "clang/Sema/DelayedDiagnostic.h"
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#include "clang/Sema/Lookup.h"
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#include "clang/Sema/ScopeInfo.h"
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#include "clang/Sema/SemaInternal.h"
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#include "llvm/ADT/StringExtras.h"
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using namespace clang;
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using namespace sema;
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static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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FallThroughAttr Attr(S.Context, A);
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if (isa<SwitchCase>(St)) {
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S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
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<< A << St->getBeginLoc();
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SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
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S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
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<< FixItHint::CreateInsertion(L, ";");
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return nullptr;
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}
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auto *FnScope = S.getCurFunction();
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if (FnScope->SwitchStack.empty()) {
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S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
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return nullptr;
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}
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// If this is spelled as the standard C++17 attribute, but not in C++17, warn
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// about using it as an extension.
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if (!S.getLangOpts().CPlusPlus17 && A.isCXX11Attribute() &&
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!A.getScopeName())
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S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A;
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FnScope->setHasFallthroughStmt();
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return ::new (S.Context) FallThroughAttr(S.Context, A);
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}
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static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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std::vector<StringRef> DiagnosticIdentifiers;
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for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
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StringRef RuleName;
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if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
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return nullptr;
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// FIXME: Warn if the rule name is unknown. This is tricky because only
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// clang-tidy knows about available rules.
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DiagnosticIdentifiers.push_back(RuleName);
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}
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return ::new (S.Context) SuppressAttr(
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S.Context, A, DiagnosticIdentifiers.data(), DiagnosticIdentifiers.size());
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}
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static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange) {
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IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
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IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
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IdentifierLoc *StateLoc = A.getArgAsIdent(2);
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Expr *ValueExpr = A.getArgAsExpr(3);
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StringRef PragmaName =
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llvm::StringSwitch<StringRef>(PragmaNameLoc->Ident->getName())
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.Cases("unroll", "nounroll", "unroll_and_jam", "nounroll_and_jam",
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PragmaNameLoc->Ident->getName())
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.Default("clang loop");
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// This could be handled automatically by adding a Subjects definition in
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// Attr.td, but that would make the diagnostic behavior worse in this case
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// because the user spells this attribute as a pragma.
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if (!isa<DoStmt, ForStmt, CXXForRangeStmt, WhileStmt>(St)) {
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std::string Pragma = "#pragma " + std::string(PragmaName);
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S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
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return nullptr;
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}
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LoopHintAttr::OptionType Option;
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LoopHintAttr::LoopHintState State;
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auto SetHints = [&Option, &State](LoopHintAttr::OptionType O,
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LoopHintAttr::LoopHintState S) {
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Option = O;
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State = S;
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};
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if (PragmaName == "nounroll") {
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SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);
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} else if (PragmaName == "unroll") {
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// #pragma unroll N
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if (ValueExpr)
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SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
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else
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SetHints(LoopHintAttr::Unroll, LoopHintAttr::Enable);
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} else if (PragmaName == "nounroll_and_jam") {
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SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Disable);
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} else if (PragmaName == "unroll_and_jam") {
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// #pragma unroll_and_jam N
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if (ValueExpr)
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SetHints(LoopHintAttr::UnrollAndJamCount, LoopHintAttr::Numeric);
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else
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SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Enable);
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} else {
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// #pragma clang loop ...
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assert(OptionLoc && OptionLoc->Ident &&
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"Attribute must have valid option info.");
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Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
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OptionLoc->Ident->getName())
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.Case("vectorize", LoopHintAttr::Vectorize)
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.Case("vectorize_width", LoopHintAttr::VectorizeWidth)
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.Case("interleave", LoopHintAttr::Interleave)
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.Case("vectorize_predicate", LoopHintAttr::VectorizePredicate)
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.Case("interleave_count", LoopHintAttr::InterleaveCount)
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.Case("unroll", LoopHintAttr::Unroll)
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.Case("unroll_count", LoopHintAttr::UnrollCount)
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.Case("pipeline", LoopHintAttr::PipelineDisabled)
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.Case("pipeline_initiation_interval",
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LoopHintAttr::PipelineInitiationInterval)
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.Case("distribute", LoopHintAttr::Distribute)
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.Default(LoopHintAttr::Vectorize);
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if (Option == LoopHintAttr::VectorizeWidth) {
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assert((ValueExpr || (StateLoc && StateLoc->Ident)) &&
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"Attribute must have a valid value expression or argument.");
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if (ValueExpr && S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
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return nullptr;
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if (StateLoc && StateLoc->Ident && StateLoc->Ident->isStr("scalable"))
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State = LoopHintAttr::ScalableWidth;
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else
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State = LoopHintAttr::FixedWidth;
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} else if (Option == LoopHintAttr::InterleaveCount ||
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Option == LoopHintAttr::UnrollCount ||
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Option == LoopHintAttr::PipelineInitiationInterval) {
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assert(ValueExpr && "Attribute must have a valid value expression.");
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if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
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return nullptr;
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State = LoopHintAttr::Numeric;
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} else if (Option == LoopHintAttr::Vectorize ||
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Option == LoopHintAttr::Interleave ||
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Option == LoopHintAttr::VectorizePredicate ||
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Option == LoopHintAttr::Unroll ||
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Option == LoopHintAttr::Distribute ||
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Option == LoopHintAttr::PipelineDisabled) {
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assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
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if (StateLoc->Ident->isStr("disable"))
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State = LoopHintAttr::Disable;
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else if (StateLoc->Ident->isStr("assume_safety"))
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State = LoopHintAttr::AssumeSafety;
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else if (StateLoc->Ident->isStr("full"))
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State = LoopHintAttr::Full;
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else if (StateLoc->Ident->isStr("enable"))
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State = LoopHintAttr::Enable;
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else
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llvm_unreachable("bad loop hint argument");
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} else
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llvm_unreachable("bad loop hint");
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}
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return LoopHintAttr::CreateImplicit(S.Context, Option, State, ValueExpr, A);
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}
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namespace {
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class CallExprFinder : public ConstEvaluatedExprVisitor<CallExprFinder> {
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bool FoundCallExpr = false;
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public:
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typedef ConstEvaluatedExprVisitor<CallExprFinder> Inherited;
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CallExprFinder(Sema &S, const Stmt *St) : Inherited(S.Context) { Visit(St); }
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bool foundCallExpr() { return FoundCallExpr; }
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void VisitCallExpr(const CallExpr *E) { FoundCallExpr = true; }
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void VisitAsmStmt(const AsmStmt *S) { FoundCallExpr = true; }
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void Visit(const Stmt *St) {
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if (!St)
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return;
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ConstEvaluatedExprVisitor<CallExprFinder>::Visit(St);
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}
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};
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} // namespace
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static Attr *handleNoMergeAttr(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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NoMergeAttr NMA(S.Context, A);
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CallExprFinder CEF(S, St);
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if (!CEF.foundCallExpr()) {
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S.Diag(St->getBeginLoc(), diag::warn_nomerge_attribute_ignored_in_stmt)
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<< NMA.getSpelling();
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return nullptr;
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}
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return ::new (S.Context) NoMergeAttr(S.Context, A);
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}
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static Attr *handleLikely(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
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S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
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return ::new (S.Context) LikelyAttr(S.Context, A);
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}
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static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
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S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
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return ::new (S.Context) UnlikelyAttr(S.Context, A);
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}
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static void
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CheckForIncompatibleAttributes(Sema &S,
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const SmallVectorImpl<const Attr *> &Attrs) {
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// There are 6 categories of loop hints attributes: vectorize, interleave,
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// unroll, unroll_and_jam, pipeline and distribute. Except for distribute they
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// come in two variants: a state form and a numeric form. The state form
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// selectively defaults/enables/disables the transformation for the loop
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// (for unroll, default indicates full unrolling rather than enabling the
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// transformation). The numeric form form provides an integer hint (for
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// example, unroll count) to the transformer. The following array accumulates
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// the hints encountered while iterating through the attributes to check for
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// compatibility.
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struct {
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const LoopHintAttr *StateAttr;
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const LoopHintAttr *NumericAttr;
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} HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
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{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
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{nullptr, nullptr}};
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for (const auto *I : Attrs) {
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const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
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// Skip non loop hint attributes
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if (!LH)
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continue;
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LoopHintAttr::OptionType Option = LH->getOption();
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enum {
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Vectorize,
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Interleave,
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Unroll,
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UnrollAndJam,
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Distribute,
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Pipeline,
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VectorizePredicate
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} Category;
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switch (Option) {
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case LoopHintAttr::Vectorize:
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case LoopHintAttr::VectorizeWidth:
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Category = Vectorize;
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break;
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case LoopHintAttr::Interleave:
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case LoopHintAttr::InterleaveCount:
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Category = Interleave;
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break;
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case LoopHintAttr::Unroll:
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case LoopHintAttr::UnrollCount:
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Category = Unroll;
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break;
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case LoopHintAttr::UnrollAndJam:
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case LoopHintAttr::UnrollAndJamCount:
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Category = UnrollAndJam;
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break;
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case LoopHintAttr::Distribute:
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// Perform the check for duplicated 'distribute' hints.
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Category = Distribute;
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break;
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case LoopHintAttr::PipelineDisabled:
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case LoopHintAttr::PipelineInitiationInterval:
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Category = Pipeline;
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break;
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case LoopHintAttr::VectorizePredicate:
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Category = VectorizePredicate;
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break;
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};
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assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
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auto &CategoryState = HintAttrs[Category];
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const LoopHintAttr *PrevAttr;
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if (Option == LoopHintAttr::Vectorize ||
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Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
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Option == LoopHintAttr::UnrollAndJam ||
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Option == LoopHintAttr::VectorizePredicate ||
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Option == LoopHintAttr::PipelineDisabled ||
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Option == LoopHintAttr::Distribute) {
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// Enable|Disable|AssumeSafety hint. For example, vectorize(enable).
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PrevAttr = CategoryState.StateAttr;
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CategoryState.StateAttr = LH;
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} else {
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// Numeric hint. For example, vectorize_width(8).
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PrevAttr = CategoryState.NumericAttr;
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CategoryState.NumericAttr = LH;
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}
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PrintingPolicy Policy(S.Context.getLangOpts());
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SourceLocation OptionLoc = LH->getRange().getBegin();
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if (PrevAttr)
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// Cannot specify same type of attribute twice.
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S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
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<< /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
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<< LH->getDiagnosticName(Policy);
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if (CategoryState.StateAttr && CategoryState.NumericAttr &&
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(Category == Unroll || Category == UnrollAndJam ||
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CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
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// Disable hints are not compatible with numeric hints of the same
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// category. As a special case, numeric unroll hints are also not
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// compatible with enable or full form of the unroll pragma because these
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// directives indicate full unrolling.
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S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
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<< /*Duplicate=*/false
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<< CategoryState.StateAttr->getDiagnosticName(Policy)
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<< CategoryState.NumericAttr->getDiagnosticName(Policy);
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}
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}
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}
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static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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// Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's
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// useful for OpenCL 1.x too and doesn't require HW support.
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// opencl_unroll_hint can have 0 arguments (compiler
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// determines unrolling factor) or 1 argument (the unroll factor provided
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// by the user).
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unsigned UnrollFactor = 0;
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if (A.getNumArgs() == 1) {
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Expr *E = A.getArgAsExpr(0);
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Optional<llvm::APSInt> ArgVal;
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if (!(ArgVal = E->getIntegerConstantExpr(S.Context))) {
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S.Diag(A.getLoc(), diag::err_attribute_argument_type)
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<< A << AANT_ArgumentIntegerConstant << E->getSourceRange();
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return nullptr;
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}
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int Val = ArgVal->getSExtValue();
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if (Val <= 0) {
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S.Diag(A.getRange().getBegin(),
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diag::err_attribute_requires_positive_integer)
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<< A << /* positive */ 0;
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return nullptr;
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}
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UnrollFactor = static_cast<unsigned>(Val);
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}
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return ::new (S.Context) OpenCLUnrollHintAttr(S.Context, A, UnrollFactor);
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}
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static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
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SourceRange Range) {
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if (A.isInvalid() || A.getKind() == ParsedAttr::IgnoredAttribute)
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return nullptr;
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// Unknown attributes are automatically warned on. Target-specific attributes
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// which do not apply to the current target architecture are treated as
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// though they were unknown attributes.
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const TargetInfo *Aux = S.Context.getAuxTargetInfo();
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if (A.getKind() == ParsedAttr::UnknownAttribute ||
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!(A.existsInTarget(S.Context.getTargetInfo()) ||
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(S.Context.getLangOpts().SYCLIsDevice && Aux &&
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A.existsInTarget(*Aux)))) {
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S.Diag(A.getLoc(), A.isDeclspecAttribute()
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? (unsigned)diag::warn_unhandled_ms_attribute_ignored
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: (unsigned)diag::warn_unknown_attribute_ignored)
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<< A << A.getRange();
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return nullptr;
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}
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if (S.checkCommonAttributeFeatures(St, A))
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return nullptr;
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switch (A.getKind()) {
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case ParsedAttr::AT_FallThrough:
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return handleFallThroughAttr(S, St, A, Range);
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case ParsedAttr::AT_LoopHint:
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return handleLoopHintAttr(S, St, A, Range);
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case ParsedAttr::AT_OpenCLUnrollHint:
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return handleOpenCLUnrollHint(S, St, A, Range);
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case ParsedAttr::AT_Suppress:
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return handleSuppressAttr(S, St, A, Range);
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case ParsedAttr::AT_NoMerge:
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return handleNoMergeAttr(S, St, A, Range);
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case ParsedAttr::AT_Likely:
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return handleLikely(S, St, A, Range);
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case ParsedAttr::AT_Unlikely:
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return handleUnlikely(S, St, A, Range);
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default:
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// N.B., ClangAttrEmitter.cpp emits a diagnostic helper that ensures a
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// declaration attribute is not written on a statement, but this code is
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// needed for attributes in Attr.td that do not list any subjects.
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S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
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<< A << St->getBeginLoc();
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return nullptr;
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}
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}
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StmtResult Sema::ProcessStmtAttributes(Stmt *S,
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const ParsedAttributesView &AttrList,
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SourceRange Range) {
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SmallVector<const Attr*, 8> Attrs;
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for (const ParsedAttr &AL : AttrList) {
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if (Attr *a = ProcessStmtAttribute(*this, S, AL, Range))
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Attrs.push_back(a);
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}
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CheckForIncompatibleAttributes(*this, Attrs);
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if (Attrs.empty())
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return S;
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return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
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}
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