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//===--- SemaAttr.cpp - Semantic Analysis for Attributes ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for non-trivial attributes and
// pragmas.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "clang/AST/Expr.h"
using namespace clang;
//===----------------------------------------------------------------------===//
// Pragma Packed
//===----------------------------------------------------------------------===//
namespace {
/// PragmaPackStack - Simple class to wrap the stack used by #pragma
/// pack.
class PragmaPackStack {
typedef std::vector< std::pair<unsigned, IdentifierInfo*> > stack_ty;
/// Alignment - The current user specified alignment.
unsigned Alignment;
/// Stack - Entries in the #pragma pack stack, consisting of saved
/// alignments and optional names.
stack_ty Stack;
public:
PragmaPackStack() : Alignment(0) {}
void setAlignment(unsigned A) { Alignment = A; }
unsigned getAlignment() { return Alignment; }
/// push - Push the current alignment onto the stack, optionally
/// using the given \arg Name for the record, if non-zero.
void push(IdentifierInfo *Name) {
Stack.push_back(std::make_pair(Alignment, Name));
}
/// pop - Pop a record from the stack and restore the current
/// alignment to the previous value. If \arg Name is non-zero then
/// the first such named record is popped, otherwise the top record
/// is popped. Returns true if the pop succeeded.
bool pop(IdentifierInfo *Name);
};
} // end anonymous namespace.
bool PragmaPackStack::pop(IdentifierInfo *Name) {
if (Stack.empty())
return false;
// If name is empty just pop top.
if (!Name) {
Alignment = Stack.back().first;
Stack.pop_back();
return true;
}
// Otherwise, find the named record.
for (unsigned i = Stack.size(); i != 0; ) {
--i;
if (Stack[i].second == Name) {
// Found it, pop up to and including this record.
Alignment = Stack[i].first;
Stack.erase(Stack.begin() + i, Stack.end());
return true;
}
}
return false;
}
/// FreePackedContext - Deallocate and null out PackContext.
void Sema::FreePackedContext() {
delete static_cast<PragmaPackStack*>(PackContext);
PackContext = 0;
}
/// getPragmaPackAlignment() - Return the current alignment as specified by
/// the current #pragma pack directive, or 0 if none is currently active.
unsigned Sema::getPragmaPackAlignment() const {
if (PackContext)
return static_cast<PragmaPackStack*>(PackContext)->getAlignment();
return 0;
}
void Sema::ActOnPragmaPack(PragmaPackKind Kind, IdentifierInfo *Name,
ExprTy *alignment, SourceLocation PragmaLoc,
SourceLocation LParenLoc, SourceLocation RParenLoc) {
Expr *Alignment = static_cast<Expr *>(alignment);
// If specified then alignment must be a "small" power of two.
unsigned AlignmentVal = 0;
if (Alignment) {
llvm::APSInt Val;
// pack(0) is like pack(), which just works out since that is what
// we use 0 for in PackAttr.
if (!Alignment->isIntegerConstantExpr(Val, Context) ||
!(Val == 0 || Val.isPowerOf2()) ||
Val.getZExtValue() > 16) {
Diag(PragmaLoc, diag::warn_pragma_pack_invalid_alignment);
Alignment->Destroy(Context);
return; // Ignore
}
AlignmentVal = (unsigned) Val.getZExtValue();
}
if (PackContext == 0)
PackContext = new PragmaPackStack();
PragmaPackStack *Context = static_cast<PragmaPackStack*>(PackContext);
switch (Kind) {
case Action::PPK_Default: // pack([n])
Context->setAlignment(AlignmentVal);
break;
case Action::PPK_Show: // pack(show)
// Show the current alignment, making sure to show the right value
// for the default.
AlignmentVal = Context->getAlignment();
// FIXME: This should come from the target.
if (AlignmentVal == 0)
AlignmentVal = 8;
Diag(PragmaLoc, diag::warn_pragma_pack_show) << AlignmentVal;
break;
case Action::PPK_Push: // pack(push [, id] [, [n])
Context->push(Name);
// Set the new alignment if specified.
if (Alignment)
Context->setAlignment(AlignmentVal);
break;
case Action::PPK_Pop: // pack(pop [, id] [, n])
// MSDN, C/C++ Preprocessor Reference > Pragma Directives > pack:
// "#pragma pack(pop, identifier, n) is undefined"
if (Alignment && Name)
Diag(PragmaLoc, diag::warn_pragma_pack_pop_identifer_and_alignment);
// Do the pop.
if (!Context->pop(Name)) {
// If a name was specified then failure indicates the name
// wasn't found. Otherwise failure indicates the stack was
// empty.
Diag(PragmaLoc, diag::warn_pragma_pack_pop_failed)
<< (Name ? "no record matching name" : "stack empty");
// FIXME: Warn about popping named records as MSVC does.
} else {
// Pop succeeded, set the new alignment if specified.
if (Alignment)
Context->setAlignment(AlignmentVal);
}
break;
default:
assert(0 && "Invalid #pragma pack kind.");
}
}
void Sema::ActOnPragmaUnused(ExprTy **Exprs, unsigned NumExprs,
SourceLocation PragmaLoc,
SourceLocation LParenLoc,
SourceLocation RParenLoc) {
// Verify that all of the expressions are valid before
// modifying the attributes of any referenced decl.
Expr *ErrorExpr = 0;
for (unsigned i = 0; i < NumExprs; ++i) {
Expr *Ex = (Expr*) Exprs[i];
if (!isa<DeclRefExpr>(Ex)) {
ErrorExpr = Ex;
break;
}
Decl *d = cast<DeclRefExpr>(Ex)->getDecl();;
if (!isa<VarDecl>(d) || !cast<VarDecl>(d)->hasLocalStorage()) {
ErrorExpr = Ex;
break;
}
}
// Delete the expressions if we encountered any error.
if (ErrorExpr) {
Diag(ErrorExpr->getLocStart(), diag::warn_pragma_unused_expected_localvar);
for (unsigned i = 0; i < NumExprs; ++i)
((Expr*) Exprs[i])->Destroy(Context);
return;
}
// Otherwise, add the 'unused' attribute to each referenced declaration.
for (unsigned i = 0; i < NumExprs; ++i) {
DeclRefExpr *DR = (DeclRefExpr*) Exprs[i];
DR->getDecl()->addAttr(Context, ::new (Context) UnusedAttr());
DR->Destroy(Context);
}
}
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