diff options
Diffstat (limited to 'contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp | 360 |
1 files changed, 342 insertions, 18 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp index cd23811..99bc3f4 100644 --- a/contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp +++ b/contrib/llvm/tools/clang/lib/CodeGen/CGStmt.cpp @@ -72,6 +72,8 @@ void CodeGenFunction::EmitStmt(const Stmt *S) { switch (S->getStmtClass()) { case Stmt::NoStmtClass: case Stmt::CXXCatchStmtClass: + case Stmt::SEHExceptStmtClass: + case Stmt::SEHFinallyStmtClass: llvm_unreachable("invalid statement class to emit generically"); case Stmt::NullStmtClass: case Stmt::CompoundStmtClass: @@ -153,6 +155,11 @@ void CodeGenFunction::EmitStmt(const Stmt *S) { case Stmt::CXXTryStmtClass: EmitCXXTryStmt(cast<CXXTryStmt>(*S)); break; + case Stmt::CXXForRangeStmtClass: + EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S)); + case Stmt::SEHTryStmtClass: + // FIXME Not yet implemented + break; } } @@ -359,10 +366,12 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) { // If the condition constant folds and can be elided, try to avoid emitting // the condition and the dead arm of the if/else. - if (int Cond = ConstantFoldsToSimpleInteger(S.getCond())) { + bool CondConstant; + if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) { // Figure out which block (then or else) is executed. - const Stmt *Executed = S.getThen(), *Skipped = S.getElse(); - if (Cond == -1) // Condition false? + const Stmt *Executed = S.getThen(); + const Stmt *Skipped = S.getElse(); + if (!CondConstant) // Condition false? std::swap(Executed, Skipped); // If the skipped block has no labels in it, just emit the executed block. @@ -395,11 +404,17 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) { // Emit the 'else' code if present. if (const Stmt *Else = S.getElse()) { + // There is no need to emit line number for unconditional branch. + if (getDebugInfo()) + Builder.SetCurrentDebugLocation(llvm::DebugLoc()); EmitBlock(ElseBlock); { RunCleanupsScope ElseScope(*this); EmitStmt(Else); } + // There is no need to emit line number for unconditional branch. + if (getDebugInfo()) + Builder.SetCurrentDebugLocation(llvm::DebugLoc()); EmitBranch(ContBlock); } @@ -628,6 +643,80 @@ void CodeGenFunction::EmitForStmt(const ForStmt &S) { EmitBlock(LoopExit.getBlock(), true); } +void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) { + JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); + + RunCleanupsScope ForScope(*this); + + CGDebugInfo *DI = getDebugInfo(); + if (DI) { + DI->setLocation(S.getSourceRange().getBegin()); + DI->EmitRegionStart(Builder); + } + + // Evaluate the first pieces before the loop. + EmitStmt(S.getRangeStmt()); + EmitStmt(S.getBeginEndStmt()); + + // Start the loop with a block that tests the condition. + // If there's an increment, the continue scope will be overwritten + // later. + llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); + EmitBlock(CondBlock); + + // If there are any cleanups between here and the loop-exit scope, + // create a block to stage a loop exit along. + llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); + if (ForScope.requiresCleanups()) + ExitBlock = createBasicBlock("for.cond.cleanup"); + + // The loop body, consisting of the specified body and the loop variable. + llvm::BasicBlock *ForBody = createBasicBlock("for.body"); + + // The body is executed if the expression, contextually converted + // to bool, is true. + llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); + Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); + + if (ExitBlock != LoopExit.getBlock()) { + EmitBlock(ExitBlock); + EmitBranchThroughCleanup(LoopExit); + } + + EmitBlock(ForBody); + + // Create a block for the increment. In case of a 'continue', we jump there. + JumpDest Continue = getJumpDestInCurrentScope("for.inc"); + + // Store the blocks to use for break and continue. + BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); + + { + // Create a separate cleanup scope for the loop variable and body. + RunCleanupsScope BodyScope(*this); + EmitStmt(S.getLoopVarStmt()); + EmitStmt(S.getBody()); + } + + // If there is an increment, emit it next. + EmitBlock(Continue.getBlock()); + EmitStmt(S.getInc()); + + BreakContinueStack.pop_back(); + + EmitBranch(CondBlock); + + ForScope.ForceCleanup(); + + if (DI) { + DI->setLocation(S.getSourceRange().getEnd()); + DI->EmitRegionEnd(Builder); + } + + // Emit the fall-through block. + EmitBlock(LoopExit.getBlock(), true); +} + void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { if (RV.isScalar()) { Builder.CreateStore(RV.getScalarVal(), ReturnValue); @@ -745,8 +834,7 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { // Range is small enough to add multiple switch instruction cases. for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { - SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), LHS), - CaseDest); + SwitchInsn->addCase(Builder.getInt(LHS), CaseDest); LHS++; } return; @@ -767,11 +855,9 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { // Emit range check. llvm::Value *Diff = - Builder.CreateSub(SwitchInsn->getCondition(), - llvm::ConstantInt::get(getLLVMContext(), LHS), "tmp"); + Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS), "tmp"); llvm::Value *Cond = - Builder.CreateICmpULE(Diff, llvm::ConstantInt::get(getLLVMContext(), Range), - "inbounds"); + Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds"); Builder.CreateCondBr(Cond, CaseDest, FalseDest); // Restore the appropriate insertion point. @@ -782,16 +868,37 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { } void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { + // Handle case ranges. if (S.getRHS()) { EmitCaseStmtRange(S); return; } + llvm::ConstantInt *CaseVal = + Builder.getInt(S.getLHS()->EvaluateAsInt(getContext())); + + // If the body of the case is just a 'break', and if there was no fallthrough, + // try to not emit an empty block. + if (isa<BreakStmt>(S.getSubStmt())) { + JumpDest Block = BreakContinueStack.back().BreakBlock; + + // Only do this optimization if there are no cleanups that need emitting. + if (isObviouslyBranchWithoutCleanups(Block)) { + SwitchInsn->addCase(CaseVal, Block.getBlock()); + + // If there was a fallthrough into this case, make sure to redirect it to + // the end of the switch as well. + if (Builder.GetInsertBlock()) { + Builder.CreateBr(Block.getBlock()); + Builder.ClearInsertionPoint(); + } + return; + } + } + EmitBlock(createBasicBlock("sw.bb")); llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); - llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext()); - SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal), - CaseDest); + SwitchInsn->addCase(CaseVal, CaseDest); // Recursively emitting the statement is acceptable, but is not wonderful for // code where we have many case statements nested together, i.e.: @@ -805,13 +912,12 @@ void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { const CaseStmt *CurCase = &S; const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); - // Otherwise, iteratively add consequtive cases to this switch stmt. + // Otherwise, iteratively add consecutive cases to this switch stmt. while (NextCase && NextCase->getRHS() == 0) { CurCase = NextCase; - CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext()); - SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal), - CaseDest); - + llvm::ConstantInt *CaseVal = + Builder.getInt(CurCase->getLHS()->EvaluateAsInt(getContext())); + SwitchInsn->addCase(CaseVal, CaseDest); NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); } @@ -827,6 +933,207 @@ void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { EmitStmt(S.getSubStmt()); } +/// CollectStatementsForCase - Given the body of a 'switch' statement and a +/// constant value that is being switched on, see if we can dead code eliminate +/// the body of the switch to a simple series of statements to emit. Basically, +/// on a switch (5) we want to find these statements: +/// case 5: +/// printf(...); <-- +/// ++i; <-- +/// break; +/// +/// and add them to the ResultStmts vector. If it is unsafe to do this +/// transformation (for example, one of the elided statements contains a label +/// that might be jumped to), return CSFC_Failure. If we handled it and 'S' +/// should include statements after it (e.g. the printf() line is a substmt of +/// the case) then return CSFC_FallThrough. If we handled it and found a break +/// statement, then return CSFC_Success. +/// +/// If Case is non-null, then we are looking for the specified case, checking +/// that nothing we jump over contains labels. If Case is null, then we found +/// the case and are looking for the break. +/// +/// If the recursive walk actually finds our Case, then we set FoundCase to +/// true. +/// +enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success }; +static CSFC_Result CollectStatementsForCase(const Stmt *S, + const SwitchCase *Case, + bool &FoundCase, + llvm::SmallVectorImpl<const Stmt*> &ResultStmts) { + // If this is a null statement, just succeed. + if (S == 0) + return Case ? CSFC_Success : CSFC_FallThrough; + + // If this is the switchcase (case 4: or default) that we're looking for, then + // we're in business. Just add the substatement. + if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) { + if (S == Case) { + FoundCase = true; + return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase, + ResultStmts); + } + + // Otherwise, this is some other case or default statement, just ignore it. + return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase, + ResultStmts); + } + + // If we are in the live part of the code and we found our break statement, + // return a success! + if (Case == 0 && isa<BreakStmt>(S)) + return CSFC_Success; + + // If this is a switch statement, then it might contain the SwitchCase, the + // break, or neither. + if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { + // Handle this as two cases: we might be looking for the SwitchCase (if so + // the skipped statements must be skippable) or we might already have it. + CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end(); + if (Case) { + // Keep track of whether we see a skipped declaration. The code could be + // using the declaration even if it is skipped, so we can't optimize out + // the decl if the kept statements might refer to it. + bool HadSkippedDecl = false; + + // If we're looking for the case, just see if we can skip each of the + // substatements. + for (; Case && I != E; ++I) { + HadSkippedDecl |= isa<DeclStmt>(I); + + switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) { + case CSFC_Failure: return CSFC_Failure; + case CSFC_Success: + // A successful result means that either 1) that the statement doesn't + // have the case and is skippable, or 2) does contain the case value + // and also contains the break to exit the switch. In the later case, + // we just verify the rest of the statements are elidable. + if (FoundCase) { + // If we found the case and skipped declarations, we can't do the + // optimization. + if (HadSkippedDecl) + return CSFC_Failure; + + for (++I; I != E; ++I) + if (CodeGenFunction::ContainsLabel(*I, true)) + return CSFC_Failure; + return CSFC_Success; + } + break; + case CSFC_FallThrough: + // If we have a fallthrough condition, then we must have found the + // case started to include statements. Consider the rest of the + // statements in the compound statement as candidates for inclusion. + assert(FoundCase && "Didn't find case but returned fallthrough?"); + // We recursively found Case, so we're not looking for it anymore. + Case = 0; + + // If we found the case and skipped declarations, we can't do the + // optimization. + if (HadSkippedDecl) + return CSFC_Failure; + break; + } + } + } + + // If we have statements in our range, then we know that the statements are + // live and need to be added to the set of statements we're tracking. + for (; I != E; ++I) { + switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) { + case CSFC_Failure: return CSFC_Failure; + case CSFC_FallThrough: + // A fallthrough result means that the statement was simple and just + // included in ResultStmt, keep adding them afterwards. + break; + case CSFC_Success: + // A successful result means that we found the break statement and + // stopped statement inclusion. We just ensure that any leftover stmts + // are skippable and return success ourselves. + for (++I; I != E; ++I) + if (CodeGenFunction::ContainsLabel(*I, true)) + return CSFC_Failure; + return CSFC_Success; + } + } + + return Case ? CSFC_Success : CSFC_FallThrough; + } + + // Okay, this is some other statement that we don't handle explicitly, like a + // for statement or increment etc. If we are skipping over this statement, + // just verify it doesn't have labels, which would make it invalid to elide. + if (Case) { + if (CodeGenFunction::ContainsLabel(S, true)) + return CSFC_Failure; + return CSFC_Success; + } + + // Otherwise, we want to include this statement. Everything is cool with that + // so long as it doesn't contain a break out of the switch we're in. + if (CodeGenFunction::containsBreak(S)) return CSFC_Failure; + + // Otherwise, everything is great. Include the statement and tell the caller + // that we fall through and include the next statement as well. + ResultStmts.push_back(S); + return CSFC_FallThrough; +} + +/// FindCaseStatementsForValue - Find the case statement being jumped to and +/// then invoke CollectStatementsForCase to find the list of statements to emit +/// for a switch on constant. See the comment above CollectStatementsForCase +/// for more details. +static bool FindCaseStatementsForValue(const SwitchStmt &S, + const llvm::APInt &ConstantCondValue, + llvm::SmallVectorImpl<const Stmt*> &ResultStmts, + ASTContext &C) { + // First step, find the switch case that is being branched to. We can do this + // efficiently by scanning the SwitchCase list. + const SwitchCase *Case = S.getSwitchCaseList(); + const DefaultStmt *DefaultCase = 0; + + for (; Case; Case = Case->getNextSwitchCase()) { + // It's either a default or case. Just remember the default statement in + // case we're not jumping to any numbered cases. + if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) { + DefaultCase = DS; + continue; + } + + // Check to see if this case is the one we're looking for. + const CaseStmt *CS = cast<CaseStmt>(Case); + // Don't handle case ranges yet. + if (CS->getRHS()) return false; + + // If we found our case, remember it as 'case'. + if (CS->getLHS()->EvaluateAsInt(C) == ConstantCondValue) + break; + } + + // If we didn't find a matching case, we use a default if it exists, or we + // elide the whole switch body! + if (Case == 0) { + // It is safe to elide the body of the switch if it doesn't contain labels + // etc. If it is safe, return successfully with an empty ResultStmts list. + if (DefaultCase == 0) + return !CodeGenFunction::ContainsLabel(&S); + Case = DefaultCase; + } + + // Ok, we know which case is being jumped to, try to collect all the + // statements that follow it. This can fail for a variety of reasons. Also, + // check to see that the recursive walk actually found our case statement. + // Insane cases like this can fail to find it in the recursive walk since we + // don't handle every stmt kind: + // switch (4) { + // while (1) { + // case 4: ... + bool FoundCase = false; + return CollectStatementsForCase(S.getBody(), Case, FoundCase, + ResultStmts) != CSFC_Failure && + FoundCase; +} + void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog"); @@ -835,6 +1142,23 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { if (S.getConditionVariable()) EmitAutoVarDecl(*S.getConditionVariable()); + // See if we can constant fold the condition of the switch and therefore only + // emit the live case statement (if any) of the switch. + llvm::APInt ConstantCondValue; + if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) { + llvm::SmallVector<const Stmt*, 4> CaseStmts; + if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts, + getContext())) { + RunCleanupsScope ExecutedScope(*this); + + // Okay, we can dead code eliminate everything except this case. Emit the + // specified series of statements and we're good. + for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i) + EmitStmt(CaseStmts[i]); + return; + } + } + llvm::Value *CondV = EmitScalarExpr(S.getCond()); // Handle nested switch statements. @@ -1031,7 +1355,7 @@ static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str, } } - return llvm::MDNode::get(CGF.getLLVMContext(), Locs.data(), Locs.size()); + return llvm::MDNode::get(CGF.getLLVMContext(), Locs); } void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { |
