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//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for statements.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Expr.h"
#include "clang/AST/Stmt.h"
#include "clang/Parse/Scope.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Lex/IdentifierTable.h"
using namespace clang;
Sema::StmtResult Sema::ParseExprStmt(ExprTy *expr) {
Expr *E = static_cast<Expr*>(expr);
assert(E && "ParseExprStmt(): missing expression");
// Exprs are statements, so there is no need to do a conversion here. However,
// diagnose some potentially bad code.
if (!E->hasLocalSideEffect())
Diag(E->getExprLoc(), diag::warn_unused_expr, E->getSourceRange());
return E;
}
Sema::StmtResult Sema::ParseNullStmt(SourceLocation SemiLoc) {
return new NullStmt(SemiLoc);
}
Sema::StmtResult Sema::ParseDeclStmt(DeclTy *decl) {
if (decl)
return new DeclStmt(static_cast<Decl *>(decl));
else
return true; // error
}
Action::StmtResult
Sema::ParseCompoundStmt(SourceLocation L, SourceLocation R,
StmtTy **Elts, unsigned NumElts) {
return new CompoundStmt((Stmt**)Elts, NumElts);
}
Action::StmtResult
Sema::ParseCaseStmt(SourceLocation CaseLoc, ExprTy *lhsval,
SourceLocation DotDotDotLoc, ExprTy *rhsval,
SourceLocation ColonLoc, StmtTy *subStmt) {
Stmt *SubStmt = static_cast<Stmt*>(subStmt);
Expr *LHSVal = ((Expr *)lhsval), *RHSVal = ((Expr *)rhsval);
assert((LHSVal != 0) && "missing expression in case statement");
SourceLocation ExpLoc;
// C99 6.8.4.2p3: The expression shall be an integer constant.
if (!LHSVal->isIntegerConstantExpr(Context, &ExpLoc)) {
Diag(ExpLoc, diag::err_case_label_not_integer_constant_expr,
LHSVal->getSourceRange());
return SubStmt;
}
// GCC extension: The expression shall be an integer constant.
if (RHSVal && !RHSVal->isIntegerConstantExpr(Context, &ExpLoc)) {
Diag(ExpLoc, diag::err_case_label_not_integer_constant_expr,
RHSVal->getSourceRange());
RHSVal = 0; // Recover by just forgetting about it.
}
if (SwitchStack.empty()) {
Diag(CaseLoc, diag::err_case_not_in_switch);
return SubStmt;
}
CaseStmt *CS = new CaseStmt(LHSVal, RHSVal, SubStmt);
SwitchStack.back()->addSwitchCase(CS);
return CS;
}
Action::StmtResult
Sema::ParseDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
StmtTy *subStmt, Scope *CurScope) {
Stmt *SubStmt = static_cast<Stmt*>(subStmt);
if (SwitchStack.empty()) {
Diag(DefaultLoc, diag::err_default_not_in_switch);
return SubStmt;
}
DefaultStmt *DS = new DefaultStmt(DefaultLoc, SubStmt);
SwitchStack.back()->addSwitchCase(DS);
return DS;
}
Action::StmtResult
Sema::ParseLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
SourceLocation ColonLoc, StmtTy *subStmt) {
Stmt *SubStmt = static_cast<Stmt*>(subStmt);
// Look up the record for this label identifier.
LabelStmt *&LabelDecl = LabelMap[II];
// If not forward referenced or defined already, just create a new LabelStmt.
if (LabelDecl == 0)
return LabelDecl = new LabelStmt(IdentLoc, II, SubStmt);
assert(LabelDecl->getID() == II && "Label mismatch!");
// Otherwise, this label was either forward reference or multiply defined. If
// multiply defined, reject it now.
if (LabelDecl->getSubStmt()) {
Diag(IdentLoc, diag::err_redefinition_of_label, LabelDecl->getName());
Diag(LabelDecl->getIdentLoc(), diag::err_previous_definition);
return SubStmt;
}
// Otherwise, this label was forward declared, and we just found its real
// definition. Fill in the forward definition and return it.
LabelDecl->setIdentLoc(IdentLoc);
LabelDecl->setSubStmt(SubStmt);
return LabelDecl;
}
Action::StmtResult
Sema::ParseIfStmt(SourceLocation IfLoc, ExprTy *CondVal,
StmtTy *ThenVal, SourceLocation ElseLoc,
StmtTy *ElseVal) {
Expr *condExpr = (Expr *)CondVal;
assert(condExpr && "ParseIfStmt(): missing expression");
DefaultFunctionArrayConversion(condExpr);
QualType condType = condExpr->getType();
if (!condType->isScalarType()) // C99 6.8.4.1p1
return Diag(IfLoc, diag::err_typecheck_statement_requires_scalar,
condType.getAsString(), condExpr->getSourceRange());
return new IfStmt(condExpr, (Stmt*)ThenVal, (Stmt*)ElseVal);
}
Action::StmtResult
Sema::StartSwitchStmt(ExprTy *cond) {
Expr *Cond = static_cast<Expr*>(cond);
// C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
UsualUnaryConversions(Cond);
SwitchStmt *SS = new SwitchStmt(Cond);
SwitchStack.push_back(SS);
return SS;
}
/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
/// the specified width and sign. If an overflow occurs, detect it and emit
/// the specified diagnostic.
void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
unsigned NewWidth, bool NewSign,
SourceLocation Loc,
unsigned DiagID) {
// Perform a conversion to the promoted condition type if needed.
if (NewWidth > Val.getBitWidth()) {
// If this is an extension, just do it.
llvm::APSInt OldVal(Val);
Val.extend(NewWidth);
// If the input was signed and negative and the output is unsigned,
// warn.
if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
Diag(Loc, DiagID, OldVal.toString(), Val.toString());
Val.setIsSigned(NewSign);
} else if (NewWidth < Val.getBitWidth()) {
// If this is a truncation, check for overflow.
llvm::APSInt ConvVal(Val);
ConvVal.trunc(NewWidth);
ConvVal.extend(Val.getBitWidth());
if (ConvVal != Val)
Diag(Loc, DiagID, Val.toString(), ConvVal.toString());
// Regardless of whether a diagnostic was emitted, really do the
// truncation.
Val.trunc(NewWidth);
} else if (NewSign != Val.isSigned()) {
// Convert the sign to match the sign of the condition. This can cause
// overflow as well: unsigned(INTMIN)
llvm::APSInt OldVal(Val);
Val.setIsSigned(NewSign);
if (Val.isNegative()) // Sign bit changes meaning.
Diag(Loc, DiagID, OldVal.toString(), Val.toString());
}
}
namespace {
struct CaseCompareFunctor {
bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
const llvm::APSInt &RHS) {
return LHS.first < RHS;
}
bool operator()(const llvm::APSInt &LHS,
const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
return LHS < RHS.first;
}
};
}
Action::StmtResult
Sema::FinishSwitchStmt(SourceLocation SwitchLoc, StmtTy *Switch, ExprTy *Body) {
Stmt *BodyStmt = (Stmt*)Body;
SwitchStmt *SS = SwitchStack.back();
assert(SS == (SwitchStmt*)Switch && "switch stack missing push/pop!");
SS->setBody(BodyStmt);
SwitchStack.pop_back();
Expr *CondExpr = SS->getCond();
QualType CondType = CondExpr->getType();
if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer,
CondType.getAsString(), CondExpr->getSourceRange());
return true;
}
// Get the bitwidth of the switched-on value before promotions. We must
// convert the integer case values to this width before comparison.
unsigned CondWidth = Context.getTypeSize(CondType, SwitchLoc);
bool CondIsSigned = CondType->isSignedIntegerType();
// Accumulate all of the case values in a vector so that we can sort them
// and detect duplicates. This vector contains the APInt for the case after
// it has been converted to the condition type.
typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
CaseValsTy CaseVals;
// Keep track of any GNU case ranges we see. The APSInt is the low value.
std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
DefaultStmt *TheDefaultStmt = 0;
bool CaseListIsErroneous = false;
for (SwitchCase *SC = SS->getSwitchCaseList(); SC;
SC = SC->getNextSwitchCase()) {
if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
if (TheDefaultStmt) {
Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
Diag(TheDefaultStmt->getDefaultLoc(), diag::err_first_label);
// FIXME: Remove the default statement from the switch block so that
// we'll return a valid AST. This requires recursing down the
// AST and finding it, not something we are set up to do right now. For
// now, just lop the entire switch stmt out of the AST.
CaseListIsErroneous = true;
}
TheDefaultStmt = DS;
} else {
CaseStmt *CS = cast<CaseStmt>(SC);
// We already verified that the expression has a i-c-e value (C99
// 6.8.4.2p3) - get that value now.
llvm::APSInt LoVal(32);
CS->getLHS()->isIntegerConstantExpr(LoVal, Context);
// Convert the value to the same width/sign as the condition.
ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
CS->getLHS()->getLocStart(),
diag::warn_case_value_overflow);
// If this is a case range, remember it in CaseRanges, otherwise CaseVals.
if (CS->getRHS())
CaseRanges.push_back(std::make_pair(LoVal, CS));
else
CaseVals.push_back(std::make_pair(LoVal, CS));
}
}
// Sort all the scalar case values so we can easily detect duplicates.
std::stable_sort(CaseVals.begin(), CaseVals.end());
if (!CaseVals.empty()) {
for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
if (CaseVals[i].first == CaseVals[i+1].first) {
// If we have a duplicate, report it.
Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
diag::err_duplicate_case, CaseVals[i].first.toString());
Diag(CaseVals[i].second->getLHS()->getLocStart(),
diag::err_duplicate_case_prev);
// FIXME: We really want to remove the bogus case stmt from the substmt,
// but we have no way to do this right now.
CaseListIsErroneous = true;
}
}
}
// Detect duplicate case ranges, which usually don't exist at all in the first
// place.
if (!CaseRanges.empty()) {
// Sort all the case ranges by their low value so we can easily detect
// overlaps between ranges.
std::stable_sort(CaseRanges.begin(), CaseRanges.end());
// Scan the ranges, computing the high values and removing empty ranges.
std::vector<llvm::APSInt> HiVals;
for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
CaseStmt *CR = CaseRanges[i].second;
llvm::APSInt HiVal(32);
CR->getRHS()->isIntegerConstantExpr(HiVal, Context);
// Convert the value to the same width/sign as the condition.
ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
CR->getRHS()->getLocStart(),
diag::warn_case_value_overflow);
// If the low value is bigger than the high value, the case is empty.
if (CaseRanges[i].first > HiVal) {
Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range,
SourceRange(CR->getLHS()->getLocStart(),
CR->getRHS()->getLocEnd()));
CaseRanges.erase(CaseRanges.begin()+i);
--i, --e;
continue;
}
HiVals.push_back(HiVal);
}
// Rescan the ranges, looking for overlap with singleton values and other
// ranges. Since the range list is sorted, we only need to compare case
// ranges with their neighbors.
for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
llvm::APSInt &CRLo = CaseRanges[i].first;
llvm::APSInt &CRHi = HiVals[i];
CaseStmt *CR = CaseRanges[i].second;
// Check to see whether the case range overlaps with any singleton cases.
CaseStmt *OverlapStmt = 0;
llvm::APSInt OverlapVal(32);
// Find the smallest value >= the lower bound. If I is in the case range,
// then we have overlap.
CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
CaseVals.end(), CRLo,
CaseCompareFunctor());
if (I != CaseVals.end() && I->first < CRHi) {
OverlapVal = I->first; // Found overlap with scalar.
OverlapStmt = I->second;
}
// Find the smallest value bigger than the upper bound.
I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
OverlapVal = (I-1)->first; // Found overlap with scalar.
OverlapStmt = (I-1)->second;
}
// Check to see if this case stmt overlaps with the subsequent case range.
if (i && CRLo <= HiVals[i-1]) {
OverlapVal = HiVals[i-1]; // Found overlap with range.
OverlapStmt = CaseRanges[i-1].second;
}
if (OverlapStmt) {
// If we have a duplicate, report it.
Diag(CR->getLHS()->getLocStart(),
diag::err_duplicate_case, OverlapVal.toString());
Diag(OverlapStmt->getLHS()->getLocStart(),
diag::err_duplicate_case_prev);
// FIXME: We really want to remove the bogus case stmt from the substmt,
// but we have no way to do this right now.
CaseListIsErroneous = true;
}
}
}
// FIXME: If the case list was broken is some way, we don't have a good system
// to patch it up. Instead, just return the whole substmt as broken.
if (CaseListIsErroneous)
return true;
return SS;
}
Action::StmtResult
Sema::ParseWhileStmt(SourceLocation WhileLoc, ExprTy *Cond, StmtTy *Body) {
Expr *condExpr = (Expr *)Cond;
assert(condExpr && "ParseWhileStmt(): missing expression");
DefaultFunctionArrayConversion(condExpr);
QualType condType = condExpr->getType();
if (!condType->isScalarType()) // C99 6.8.5p2
return Diag(WhileLoc, diag::err_typecheck_statement_requires_scalar,
condType.getAsString(), condExpr->getSourceRange());
return new WhileStmt(condExpr, (Stmt*)Body);
}
Action::StmtResult
Sema::ParseDoStmt(SourceLocation DoLoc, StmtTy *Body,
SourceLocation WhileLoc, ExprTy *Cond) {
Expr *condExpr = (Expr *)Cond;
assert(condExpr && "ParseDoStmt(): missing expression");
DefaultFunctionArrayConversion(condExpr);
QualType condType = condExpr->getType();
if (!condType->isScalarType()) // C99 6.8.5p2
return Diag(DoLoc, diag::err_typecheck_statement_requires_scalar,
condType.getAsString(), condExpr->getSourceRange());
return new DoStmt((Stmt*)Body, condExpr);
}
Action::StmtResult
Sema::ParseForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
StmtTy *First, ExprTy *Second, ExprTy *Third,
SourceLocation RParenLoc, StmtTy *Body) {
if (First) {
// C99 6.8.5p3: FIXME. Need to hack Parser::ParseForStatement() and
// declaration support to create a DeclStmt node. Once this is done,
// we can test for DeclStmt vs. Expr (already a sub-class of Stmt).
}
if (Second) {
Expr *testExpr = (Expr *)Second;
DefaultFunctionArrayConversion(testExpr);
QualType testType = testExpr->getType();
if (!testType->isScalarType()) // C99 6.8.5p2
return Diag(ForLoc, diag::err_typecheck_statement_requires_scalar,
testType.getAsString(), testExpr->getSourceRange());
}
return new ForStmt((Stmt*)First, (Expr*)Second, (Expr*)Third, (Stmt*)Body);
}
Action::StmtResult
Sema::ParseGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
IdentifierInfo *LabelII) {
// Look up the record for this label identifier.
LabelStmt *&LabelDecl = LabelMap[LabelII];
// If we haven't seen this label yet, create a forward reference.
if (LabelDecl == 0)
LabelDecl = new LabelStmt(LabelLoc, LabelII, 0);
return new GotoStmt(LabelDecl);
}
Action::StmtResult
Sema::ParseIndirectGotoStmt(SourceLocation GotoLoc,SourceLocation StarLoc,
ExprTy *DestExp) {
// FIXME: Verify that the operand is convertible to void*.
return new IndirectGotoStmt((Expr*)DestExp);
}
Action::StmtResult
Sema::ParseContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
Scope *S = CurScope->getContinueParent();
if (!S) {
// C99 6.8.6.2p1: A break shall appear only in or as a loop body.
Diag(ContinueLoc, diag::err_continue_not_in_loop);
return true;
}
return new ContinueStmt();
}
Action::StmtResult
Sema::ParseBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
Scope *S = CurScope->getBreakParent();
if (!S) {
// C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
Diag(BreakLoc, diag::err_break_not_in_loop_or_switch);
return true;
}
return new BreakStmt();
}
Action::StmtResult
Sema::ParseReturnStmt(SourceLocation ReturnLoc, ExprTy *rex) {
Expr *RetValExp = static_cast<Expr *>(rex);
QualType lhsType = CurFunctionDecl->getResultType();
if (lhsType->isVoidType()) {
if (RetValExp) // C99 6.8.6.4p1 (ext_ since GCC warns)
Diag(ReturnLoc, diag::ext_return_has_expr,
CurFunctionDecl->getIdentifier()->getName(),
RetValExp->getSourceRange());
return new ReturnStmt(RetValExp);
} else {
if (!RetValExp) {
const char *funcName = CurFunctionDecl->getIdentifier()->getName();
if (getLangOptions().C99) // C99 6.8.6.4p1 (ext_ since GCC warns)
Diag(ReturnLoc, diag::ext_return_missing_expr, funcName);
else // C90 6.6.6.4p4
Diag(ReturnLoc, diag::warn_return_missing_expr, funcName);
return new ReturnStmt((Expr*)0);
}
}
// we have a non-void function with an expression, continue checking
QualType rhsType = RetValExp->getType();
// C99 6.8.6.4p3(136): The return statement is not an assignment. The
// overlap restriction of subclause 6.5.16.1 does not apply to the case of
// function return.
AssignmentCheckResult result = CheckSingleAssignmentConstraints(lhsType,
RetValExp);
// decode the result (notice that extensions still return a type).
switch (result) {
case Compatible:
break;
case Incompatible:
Diag(ReturnLoc, diag::err_typecheck_return_incompatible,
lhsType.getAsString(), rhsType.getAsString(),
RetValExp->getSourceRange());
break;
case PointerFromInt:
// check for null pointer constant (C99 6.3.2.3p3)
if (!RetValExp->isNullPointerConstant(Context)) {
Diag(ReturnLoc, diag::ext_typecheck_return_pointer_int,
lhsType.getAsString(), rhsType.getAsString(),
RetValExp->getSourceRange());
}
break;
case IntFromPointer:
Diag(ReturnLoc, diag::ext_typecheck_return_pointer_int,
lhsType.getAsString(), rhsType.getAsString(),
RetValExp->getSourceRange());
break;
case IncompatiblePointer:
Diag(ReturnLoc, diag::ext_typecheck_return_incompatible_pointer,
lhsType.getAsString(), rhsType.getAsString(),
RetValExp->getSourceRange());
break;
case CompatiblePointerDiscardsQualifiers:
Diag(ReturnLoc, diag::ext_typecheck_return_discards_qualifiers,
lhsType.getAsString(), rhsType.getAsString(),
RetValExp->getSourceRange());
break;
}
if (RetValExp) CheckReturnStackAddr(RetValExp, lhsType, ReturnLoc);
return new ReturnStmt((Expr*)RetValExp);
}