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//===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements stmt-related attribute processing.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaInternal.h"
#include "clang/AST/ASTContext.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Sema/DelayedDiagnostic.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/LoopHint.h"
#include "clang/Sema/ScopeInfo.h"
#include "llvm/ADT/StringExtras.h"
using namespace clang;
using namespace sema;
static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const AttributeList &A,
SourceRange Range) {
if (!isa<NullStmt>(St)) {
S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
<< St->getLocStart();
if (isa<SwitchCase>(St)) {
SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
<< FixItHint::CreateInsertion(L, ";");
}
return nullptr;
}
if (S.getCurFunction()->SwitchStack.empty()) {
S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
return nullptr;
}
return ::new (S.Context) FallThroughAttr(A.getRange(), S.Context,
A.getAttributeSpellingListIndex());
}
static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const AttributeList &A,
SourceRange) {
IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
IdentifierLoc *StateLoc = A.getArgAsIdent(2);
Expr *ValueExpr = A.getArgAsExpr(3);
bool PragmaUnroll = PragmaNameLoc->Ident->getName() == "unroll";
bool PragmaNoUnroll = PragmaNameLoc->Ident->getName() == "nounroll";
if (St->getStmtClass() != Stmt::DoStmtClass &&
St->getStmtClass() != Stmt::ForStmtClass &&
St->getStmtClass() != Stmt::CXXForRangeStmtClass &&
St->getStmtClass() != Stmt::WhileStmtClass) {
const char *Pragma =
llvm::StringSwitch<const char *>(PragmaNameLoc->Ident->getName())
.Case("unroll", "#pragma unroll")
.Case("nounroll", "#pragma nounroll")
.Default("#pragma clang loop");
S.Diag(St->getLocStart(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
return nullptr;
}
LoopHintAttr::Spelling Spelling;
LoopHintAttr::OptionType Option;
LoopHintAttr::LoopHintState State;
if (PragmaNoUnroll) {
// #pragma nounroll
Spelling = LoopHintAttr::Pragma_nounroll;
Option = LoopHintAttr::Unroll;
State = LoopHintAttr::Disable;
} else if (PragmaUnroll) {
Spelling = LoopHintAttr::Pragma_unroll;
if (ValueExpr) {
// #pragma unroll N
Option = LoopHintAttr::UnrollCount;
State = LoopHintAttr::Numeric;
} else {
// #pragma unroll
Option = LoopHintAttr::Unroll;
State = LoopHintAttr::Enable;
}
} else {
// #pragma clang loop ...
Spelling = LoopHintAttr::Pragma_clang_loop;
assert(OptionLoc && OptionLoc->Ident &&
"Attribute must have valid option info.");
Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
OptionLoc->Ident->getName())
.Case("vectorize", LoopHintAttr::Vectorize)
.Case("vectorize_width", LoopHintAttr::VectorizeWidth)
.Case("interleave", LoopHintAttr::Interleave)
.Case("interleave_count", LoopHintAttr::InterleaveCount)
.Case("unroll", LoopHintAttr::Unroll)
.Case("unroll_count", LoopHintAttr::UnrollCount)
.Default(LoopHintAttr::Vectorize);
if (Option == LoopHintAttr::VectorizeWidth ||
Option == LoopHintAttr::InterleaveCount ||
Option == LoopHintAttr::UnrollCount) {
assert(ValueExpr && "Attribute must have a valid value expression.");
if (S.CheckLoopHintExpr(ValueExpr, St->getLocStart()))
return nullptr;
State = LoopHintAttr::Numeric;
} else if (Option == LoopHintAttr::Vectorize ||
Option == LoopHintAttr::Interleave ||
Option == LoopHintAttr::Unroll) {
assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
if (StateLoc->Ident->isStr("disable"))
State = LoopHintAttr::Disable;
else if (StateLoc->Ident->isStr("assume_safety"))
State = LoopHintAttr::AssumeSafety;
else if (StateLoc->Ident->isStr("full"))
State = LoopHintAttr::Full;
else if (StateLoc->Ident->isStr("enable"))
State = LoopHintAttr::Enable;
else
llvm_unreachable("bad loop hint argument");
} else
llvm_unreachable("bad loop hint");
}
return LoopHintAttr::CreateImplicit(S.Context, Spelling, Option, State,
ValueExpr, A.getRange());
}
static void
CheckForIncompatibleAttributes(Sema &S,
const SmallVectorImpl<const Attr *> &Attrs) {
// There are 3 categories of loop hints attributes: vectorize, interleave,
// and unroll. Each comes in two variants: a state form and a numeric form.
// The state form selectively defaults/enables/disables the transformation
// for the loop (for unroll, default indicates full unrolling rather than
// enabling the transformation). The numeric form form provides an integer
// hint (for example, unroll count) to the transformer. The following array
// accumulates the hints encountered while iterating through the attributes
// to check for compatibility.
struct {
const LoopHintAttr *StateAttr;
const LoopHintAttr *NumericAttr;
} HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr}};
for (const auto *I : Attrs) {
const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
// Skip non loop hint attributes
if (!LH)
continue;
LoopHintAttr::OptionType Option = LH->getOption();
enum { Vectorize, Interleave, Unroll } Category;
switch (Option) {
case LoopHintAttr::Vectorize:
case LoopHintAttr::VectorizeWidth:
Category = Vectorize;
break;
case LoopHintAttr::Interleave:
case LoopHintAttr::InterleaveCount:
Category = Interleave;
break;
case LoopHintAttr::Unroll:
case LoopHintAttr::UnrollCount:
Category = Unroll;
break;
};
auto &CategoryState = HintAttrs[Category];
const LoopHintAttr *PrevAttr;
if (Option == LoopHintAttr::Vectorize ||
Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll) {
// Enable|Disable|AssumeSafety hint. For example, vectorize(enable).
PrevAttr = CategoryState.StateAttr;
CategoryState.StateAttr = LH;
} else {
// Numeric hint. For example, vectorize_width(8).
PrevAttr = CategoryState.NumericAttr;
CategoryState.NumericAttr = LH;
}
PrintingPolicy Policy(S.Context.getLangOpts());
SourceLocation OptionLoc = LH->getRange().getBegin();
if (PrevAttr)
// Cannot specify same type of attribute twice.
S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
<< /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
<< LH->getDiagnosticName(Policy);
if (CategoryState.StateAttr && CategoryState.NumericAttr &&
(Category == Unroll ||
CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
// Disable hints are not compatible with numeric hints of the same
// category. As a special case, numeric unroll hints are also not
// compatible with enable or full form of the unroll pragma because these
// directives indicate full unrolling.
S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
<< /*Duplicate=*/false
<< CategoryState.StateAttr->getDiagnosticName(Policy)
<< CategoryState.NumericAttr->getDiagnosticName(Policy);
}
}
}
static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const AttributeList &A,
SourceRange Range) {
switch (A.getKind()) {
case AttributeList::UnknownAttribute:
S.Diag(A.getLoc(), A.isDeclspecAttribute() ?
diag::warn_unhandled_ms_attribute_ignored :
diag::warn_unknown_attribute_ignored) << A.getName();
return nullptr;
case AttributeList::AT_FallThrough:
return handleFallThroughAttr(S, St, A, Range);
case AttributeList::AT_LoopHint:
return handleLoopHintAttr(S, St, A, Range);
default:
// if we're here, then we parsed a known attribute, but didn't recognize
// it as a statement attribute => it is declaration attribute
S.Diag(A.getRange().getBegin(), diag::err_attribute_invalid_on_stmt)
<< A.getName() << St->getLocStart();
return nullptr;
}
}
StmtResult Sema::ProcessStmtAttributes(Stmt *S, AttributeList *AttrList,
SourceRange Range) {
SmallVector<const Attr*, 8> Attrs;
for (const AttributeList* l = AttrList; l; l = l->getNext()) {
if (Attr *a = ProcessStmtAttribute(*this, S, *l, Range))
Attrs.push_back(a);
}
CheckForIncompatibleAttributes(*this, Attrs);
if (Attrs.empty())
return S;
return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
}
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