462 lines
17 KiB
C++
462 lines
17 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<NullStmt>(St)) {
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S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
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<< Attr.getSpelling() << St->getBeginLoc();
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if (isa<SwitchCase>(St)) {
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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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}
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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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if (A.getNumArgs() < 1) {
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S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;
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return nullptr;
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}
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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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if (St->getStmtClass() != Stmt::DoStmtClass &&
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St->getStmtClass() != Stmt::ForStmtClass &&
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St->getStmtClass() != Stmt::CXXForRangeStmtClass &&
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St->getStmtClass() != Stmt::WhileStmtClass) {
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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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if (S.CheckAttrNoArgs(A))
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return nullptr;
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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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// C++20 [dcl.attr.likelihood]p1 The attribute-token likely shall not appear
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// in an attribute-specifier-seq that contains the attribute-token unlikely.
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const LikelyAttr *Likely = nullptr;
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const UnlikelyAttr *Unlikely = nullptr;
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for (const auto *I : Attrs) {
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if (const auto *Attr = dyn_cast<LikelyAttr>(I)) {
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if (Unlikely) {
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S.Diag(Attr->getLocation(), diag::err_attributes_are_not_compatible)
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<< Attr << Unlikely << Attr->getRange();
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S.Diag(Unlikely->getLocation(), diag::note_conflicting_attribute)
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<< Unlikely->getRange();
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return;
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}
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Likely = Attr;
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} else if (const auto *Attr = dyn_cast<UnlikelyAttr>(I)) {
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if (Likely) {
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S.Diag(Attr->getLocation(), diag::err_attributes_are_not_compatible)
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<< Attr << Likely << Attr->getRange();
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S.Diag(Likely->getLocation(), diag::note_conflicting_attribute)
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<< Likely->getRange();
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return;
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}
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Unlikely = Attr;
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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 NumArgs = A.getNumArgs();
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if (NumArgs > 1) {
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S.Diag(A.getLoc(), diag::err_attribute_too_many_arguments) << A << 1;
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return nullptr;
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}
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unsigned UnrollFactor = 0;
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if (NumArgs == 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 = Val;
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}
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return OpenCLUnrollHintAttr::CreateImplicit(S.Context, 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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switch (A.getKind()) {
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case ParsedAttr::UnknownAttribute:
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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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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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// if we're here, then we parsed a known attribute, but didn't recognize
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// it as a statement attribute => it is declaration attribute
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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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