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Diffstat (limited to 'lib/CodeGen/CGStmt.cpp')
| -rw-r--r-- | lib/CodeGen/CGStmt.cpp | 1022 |
1 files changed, 1022 insertions, 0 deletions
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp new file mode 100644 index 0000000..b67996c --- /dev/null +++ b/lib/CodeGen/CGStmt.cpp @@ -0,0 +1,1022 @@ +//===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This contains code to emit Stmt nodes as LLVM code. +// +//===----------------------------------------------------------------------===// + +#include "CGDebugInfo.h" +#include "CodeGenModule.h" +#include "CodeGenFunction.h" +#include "clang/AST/StmtVisitor.h" +#include "clang/Basic/PrettyStackTrace.h" +#include "clang/Basic/TargetInfo.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/InlineAsm.h" +#include "llvm/Intrinsics.h" +#include "llvm/Target/TargetData.h" +using namespace clang; +using namespace CodeGen; + +//===----------------------------------------------------------------------===// +// Statement Emission +//===----------------------------------------------------------------------===// + +void CodeGenFunction::EmitStopPoint(const Stmt *S) { + if (CGDebugInfo *DI = getDebugInfo()) { + DI->setLocation(S->getLocStart()); + DI->EmitStopPoint(CurFn, Builder); + } +} + +void CodeGenFunction::EmitStmt(const Stmt *S) { + assert(S && "Null statement?"); + + // Check if we can handle this without bothering to generate an + // insert point or debug info. + if (EmitSimpleStmt(S)) + return; + + // If we happen to be at an unreachable point just create a dummy + // basic block to hold the code. We could change parts of irgen to + // simply not generate this code, but this situation is rare and + // probably not worth the effort. + // FIXME: Verify previous performance/effort claim. + EnsureInsertPoint(); + + // Generate a stoppoint if we are emitting debug info. + EmitStopPoint(S); + + switch (S->getStmtClass()) { + default: + // Must be an expression in a stmt context. Emit the value (to get + // side-effects) and ignore the result. + if (const Expr *E = dyn_cast<Expr>(S)) { + EmitAnyExpr(E, 0, false, true); + } else { + ErrorUnsupported(S, "statement"); + } + break; + case Stmt::IndirectGotoStmtClass: + EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; + + case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; + case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; + case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; + case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; + + case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; + case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; + + case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; + case Stmt::AsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; + + case Stmt::ObjCAtTryStmtClass: + EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); + break; + case Stmt::ObjCAtCatchStmtClass: + assert(0 && "@catch statements should be handled by EmitObjCAtTryStmt"); + break; + case Stmt::ObjCAtFinallyStmtClass: + assert(0 && "@finally statements should be handled by EmitObjCAtTryStmt"); + break; + case Stmt::ObjCAtThrowStmtClass: + EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); + break; + case Stmt::ObjCAtSynchronizedStmtClass: + EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); + break; + case Stmt::ObjCForCollectionStmtClass: + EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); + break; + } +} + +bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { + switch (S->getStmtClass()) { + default: return false; + case Stmt::NullStmtClass: break; + case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; + case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; + case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; + case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; + case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; + case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; + case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; + } + + return true; +} + +/// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, +/// this captures the expression result of the last sub-statement and returns it +/// (for use by the statement expression extension). +RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, + llvm::Value *AggLoc, bool isAggVol) { + PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), + "LLVM IR generation of compound statement ('{}')"); + + CGDebugInfo *DI = getDebugInfo(); + if (DI) { + EnsureInsertPoint(); + DI->setLocation(S.getLBracLoc()); + // FIXME: The llvm backend is currently not ready to deal with region_end + // for block scoping. In the presence of always_inline functions it gets so + // confused that it doesn't emit any debug info. Just disable this for now. + //DI->EmitRegionStart(CurFn, Builder); + } + + // Keep track of the current cleanup stack depth. + size_t CleanupStackDepth = CleanupEntries.size(); + bool OldDidCallStackSave = DidCallStackSave; + DidCallStackSave = false; + + for (CompoundStmt::const_body_iterator I = S.body_begin(), + E = S.body_end()-GetLast; I != E; ++I) + EmitStmt(*I); + + if (DI) { + EnsureInsertPoint(); + DI->setLocation(S.getRBracLoc()); + + // FIXME: The llvm backend is currently not ready to deal with region_end + // for block scoping. In the presence of always_inline functions it gets so + // confused that it doesn't emit any debug info. Just disable this for now. + //DI->EmitRegionEnd(CurFn, Builder); + } + + RValue RV; + if (!GetLast) + RV = RValue::get(0); + else { + // We have to special case labels here. They are statements, but when put + // at the end of a statement expression, they yield the value of their + // subexpression. Handle this by walking through all labels we encounter, + // emitting them before we evaluate the subexpr. + const Stmt *LastStmt = S.body_back(); + while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { + EmitLabel(*LS); + LastStmt = LS->getSubStmt(); + } + + EnsureInsertPoint(); + + RV = EmitAnyExpr(cast<Expr>(LastStmt), AggLoc); + } + + DidCallStackSave = OldDidCallStackSave; + + EmitCleanupBlocks(CleanupStackDepth); + + return RV; +} + +void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { + llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); + + // If there is a cleanup stack, then we it isn't worth trying to + // simplify this block (we would need to remove it from the scope map + // and cleanup entry). + if (!CleanupEntries.empty()) + return; + + // Can only simplify direct branches. + if (!BI || !BI->isUnconditional()) + return; + + BB->replaceAllUsesWith(BI->getSuccessor(0)); + BI->eraseFromParent(); + BB->eraseFromParent(); +} + +void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { + // Fall out of the current block (if necessary). + EmitBranch(BB); + + if (IsFinished && BB->use_empty()) { + delete BB; + return; + } + + // If necessary, associate the block with the cleanup stack size. + if (!CleanupEntries.empty()) { + // Check if the basic block has already been inserted. + BlockScopeMap::iterator I = BlockScopes.find(BB); + if (I != BlockScopes.end()) { + assert(I->second == CleanupEntries.size() - 1); + } else { + BlockScopes[BB] = CleanupEntries.size() - 1; + CleanupEntries.back().Blocks.push_back(BB); + } + } + + CurFn->getBasicBlockList().push_back(BB); + Builder.SetInsertPoint(BB); +} + +void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { + // Emit a branch from the current block to the target one if this + // was a real block. If this was just a fall-through block after a + // terminator, don't emit it. + llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); + + if (!CurBB || CurBB->getTerminator()) { + // If there is no insert point or the previous block is already + // terminated, don't touch it. + } else { + // Otherwise, create a fall-through branch. + Builder.CreateBr(Target); + } + + Builder.ClearInsertionPoint(); +} + +void CodeGenFunction::EmitLabel(const LabelStmt &S) { + EmitBlock(getBasicBlockForLabel(&S)); +} + + +void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { + EmitLabel(S); + EmitStmt(S.getSubStmt()); +} + +void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { + // If this code is reachable then emit a stop point (if generating + // debug info). We have to do this ourselves because we are on the + // "simple" statement path. + if (HaveInsertPoint()) + EmitStopPoint(&S); + + EmitBranchThroughCleanup(getBasicBlockForLabel(S.getLabel())); +} + +void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { + // Emit initial switch which will be patched up later by + // EmitIndirectSwitches(). We need a default dest, so we use the + // current BB, but this is overwritten. + llvm::Value *V = Builder.CreatePtrToInt(EmitScalarExpr(S.getTarget()), + llvm::Type::Int32Ty, + "addr"); + llvm::SwitchInst *I = Builder.CreateSwitch(V, Builder.GetInsertBlock()); + IndirectSwitches.push_back(I); + + // Clear the insertion point to indicate we are in unreachable code. + Builder.ClearInsertionPoint(); +} + +void CodeGenFunction::EmitIfStmt(const IfStmt &S) { + // C99 6.8.4.1: The first substatement is executed if the expression compares + // unequal to 0. The condition must be a scalar type. + + // 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())) { + // Figure out which block (then or else) is executed. + const Stmt *Executed = S.getThen(), *Skipped = S.getElse(); + if (Cond == -1) // Condition false? + std::swap(Executed, Skipped); + + // If the skipped block has no labels in it, just emit the executed block. + // This avoids emitting dead code and simplifies the CFG substantially. + if (!ContainsLabel(Skipped)) { + if (Executed) + EmitStmt(Executed); + return; + } + } + + // Otherwise, the condition did not fold, or we couldn't elide it. Just emit + // the conditional branch. + llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); + llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); + llvm::BasicBlock *ElseBlock = ContBlock; + if (S.getElse()) + ElseBlock = createBasicBlock("if.else"); + EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); + + // Emit the 'then' code. + EmitBlock(ThenBlock); + EmitStmt(S.getThen()); + EmitBranch(ContBlock); + + // Emit the 'else' code if present. + if (const Stmt *Else = S.getElse()) { + EmitBlock(ElseBlock); + EmitStmt(Else); + EmitBranch(ContBlock); + } + + // Emit the continuation block for code after the if. + EmitBlock(ContBlock, true); +} + +void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { + // Emit the header for the loop, insert it, which will create an uncond br to + // it. + llvm::BasicBlock *LoopHeader = createBasicBlock("while.cond"); + EmitBlock(LoopHeader); + + // Create an exit block for when the condition fails, create a block for the + // body of the loop. + llvm::BasicBlock *ExitBlock = createBasicBlock("while.end"); + llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); + + // Store the blocks to use for break and continue. + BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader)); + + // Evaluate the conditional in the while header. C99 6.8.5.1: The + // evaluation of the controlling expression takes place before each + // execution of the loop body. + llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); + + // while(1) is common, avoid extra exit blocks. Be sure + // to correctly handle break/continue though. + bool EmitBoolCondBranch = true; + if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) + if (C->isOne()) + EmitBoolCondBranch = false; + + // As long as the condition is true, go to the loop body. + if (EmitBoolCondBranch) + Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); + + // Emit the loop body. + EmitBlock(LoopBody); + EmitStmt(S.getBody()); + + BreakContinueStack.pop_back(); + + // Cycle to the condition. + EmitBranch(LoopHeader); + + // Emit the exit block. + EmitBlock(ExitBlock, true); + + // The LoopHeader typically is just a branch if we skipped emitting + // a branch, try to erase it. + if (!EmitBoolCondBranch) + SimplifyForwardingBlocks(LoopHeader); +} + +void CodeGenFunction::EmitDoStmt(const DoStmt &S) { + // Emit the body for the loop, insert it, which will create an uncond br to + // it. + llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); + llvm::BasicBlock *AfterDo = createBasicBlock("do.end"); + EmitBlock(LoopBody); + + llvm::BasicBlock *DoCond = createBasicBlock("do.cond"); + + // Store the blocks to use for break and continue. + BreakContinueStack.push_back(BreakContinue(AfterDo, DoCond)); + + // Emit the body of the loop into the block. + EmitStmt(S.getBody()); + + BreakContinueStack.pop_back(); + + EmitBlock(DoCond); + + // C99 6.8.5.2: "The evaluation of the controlling expression takes place + // after each execution of the loop body." + + // Evaluate the conditional in the while header. + // C99 6.8.5p2/p4: The first substatement is executed if the expression + // compares unequal to 0. The condition must be a scalar type. + llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); + + // "do {} while (0)" is common in macros, avoid extra blocks. Be sure + // to correctly handle break/continue though. + bool EmitBoolCondBranch = true; + if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) + if (C->isZero()) + EmitBoolCondBranch = false; + + // As long as the condition is true, iterate the loop. + if (EmitBoolCondBranch) + Builder.CreateCondBr(BoolCondVal, LoopBody, AfterDo); + + // Emit the exit block. + EmitBlock(AfterDo); + + // The DoCond block typically is just a branch if we skipped + // emitting a branch, try to erase it. + if (!EmitBoolCondBranch) + SimplifyForwardingBlocks(DoCond); +} + +void CodeGenFunction::EmitForStmt(const ForStmt &S) { + // FIXME: What do we do if the increment (f.e.) contains a stmt expression, + // which contains a continue/break? + + // Evaluate the first part before the loop. + if (S.getInit()) + EmitStmt(S.getInit()); + + // Start the loop with a block that tests the condition. + llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); + llvm::BasicBlock *AfterFor = createBasicBlock("for.end"); + + EmitBlock(CondBlock); + + // Evaluate the condition if present. If not, treat it as a + // non-zero-constant according to 6.8.5.3p2, aka, true. + if (S.getCond()) { + // As long as the condition is true, iterate the loop. + llvm::BasicBlock *ForBody = createBasicBlock("for.body"); + + // C99 6.8.5p2/p4: The first substatement is executed if the expression + // compares unequal to 0. The condition must be a scalar type. + EmitBranchOnBoolExpr(S.getCond(), ForBody, AfterFor); + + EmitBlock(ForBody); + } else { + // Treat it as a non-zero constant. Don't even create a new block for the + // body, just fall into it. + } + + // If the for loop doesn't have an increment we can just use the + // condition as the continue block. + llvm::BasicBlock *ContinueBlock; + if (S.getInc()) + ContinueBlock = createBasicBlock("for.inc"); + else + ContinueBlock = CondBlock; + + // Store the blocks to use for break and continue. + BreakContinueStack.push_back(BreakContinue(AfterFor, ContinueBlock)); + + // If the condition is true, execute the body of the for stmt. + EmitStmt(S.getBody()); + + BreakContinueStack.pop_back(); + + // If there is an increment, emit it next. + if (S.getInc()) { + EmitBlock(ContinueBlock); + EmitStmt(S.getInc()); + } + + // Finally, branch back up to the condition for the next iteration. + EmitBranch(CondBlock); + + // Emit the fall-through block. + EmitBlock(AfterFor, true); +} + +void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { + if (RV.isScalar()) { + Builder.CreateStore(RV.getScalarVal(), ReturnValue); + } else if (RV.isAggregate()) { + EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); + } else { + StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); + } + EmitBranchThroughCleanup(ReturnBlock); +} + +/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand +/// if the function returns void, or may be missing one if the function returns +/// non-void. Fun stuff :). +void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { + // Emit the result value, even if unused, to evalute the side effects. + const Expr *RV = S.getRetValue(); + + // FIXME: Clean this up by using an LValue for ReturnTemp, + // EmitStoreThroughLValue, and EmitAnyExpr. + if (!ReturnValue) { + // Make sure not to return anything, but evaluate the expression + // for side effects. + if (RV) + EmitAnyExpr(RV); + } else if (RV == 0) { + // Do nothing (return value is left uninitialized) + } else if (FnRetTy->isReferenceType()) { + // If this function returns a reference, take the address of the expression + // rather than the value. + Builder.CreateStore(EmitLValue(RV).getAddress(), ReturnValue); + } else if (!hasAggregateLLVMType(RV->getType())) { + Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); + } else if (RV->getType()->isAnyComplexType()) { + EmitComplexExprIntoAddr(RV, ReturnValue, false); + } else { + EmitAggExpr(RV, ReturnValue, false); + } + + EmitBranchThroughCleanup(ReturnBlock); +} + +void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { + for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); + I != E; ++I) + EmitDecl(**I); +} + +void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { + assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); + + // If this code is reachable then emit a stop point (if generating + // debug info). We have to do this ourselves because we are on the + // "simple" statement path. + if (HaveInsertPoint()) + EmitStopPoint(&S); + + llvm::BasicBlock *Block = BreakContinueStack.back().BreakBlock; + EmitBranchThroughCleanup(Block); +} + +void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { + assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); + + // If this code is reachable then emit a stop point (if generating + // debug info). We have to do this ourselves because we are on the + // "simple" statement path. + if (HaveInsertPoint()) + EmitStopPoint(&S); + + llvm::BasicBlock *Block = BreakContinueStack.back().ContinueBlock; + EmitBranchThroughCleanup(Block); +} + +/// EmitCaseStmtRange - If case statement range is not too big then +/// add multiple cases to switch instruction, one for each value within +/// the range. If range is too big then emit "if" condition check. +void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { + assert(S.getRHS() && "Expected RHS value in CaseStmt"); + + llvm::APSInt LHS = S.getLHS()->EvaluateAsInt(getContext()); + llvm::APSInt RHS = S.getRHS()->EvaluateAsInt(getContext()); + + // Emit the code for this case. We do this first to make sure it is + // properly chained from our predecessor before generating the + // switch machinery to enter this block. + EmitBlock(createBasicBlock("sw.bb")); + llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); + EmitStmt(S.getSubStmt()); + + // If range is empty, do nothing. + if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) + return; + + llvm::APInt Range = RHS - LHS; + // FIXME: parameters such as this should not be hardcoded. + 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(LHS), CaseDest); + LHS++; + } + return; + } + + // The range is too big. Emit "if" condition into a new block, + // making sure to save and restore the current insertion point. + llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); + + // Push this test onto the chain of range checks (which terminates + // in the default basic block). The switch's default will be changed + // to the top of this chain after switch emission is complete. + llvm::BasicBlock *FalseDest = CaseRangeBlock; + CaseRangeBlock = createBasicBlock("sw.caserange"); + + CurFn->getBasicBlockList().push_back(CaseRangeBlock); + Builder.SetInsertPoint(CaseRangeBlock); + + // Emit range check. + llvm::Value *Diff = + Builder.CreateSub(SwitchInsn->getCondition(), llvm::ConstantInt::get(LHS), + "tmp"); + llvm::Value *Cond = + Builder.CreateICmpULE(Diff, llvm::ConstantInt::get(Range), "tmp"); + Builder.CreateCondBr(Cond, CaseDest, FalseDest); + + // Restore the appropriate insertion point. + if (RestoreBB) + Builder.SetInsertPoint(RestoreBB); + else + Builder.ClearInsertionPoint(); +} + +void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { + if (S.getRHS()) { + EmitCaseStmtRange(S); + return; + } + + EmitBlock(createBasicBlock("sw.bb")); + llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); + llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext()); + SwitchInsn->addCase(llvm::ConstantInt::get(CaseVal), CaseDest); + + // Recursively emitting the statement is acceptable, but is not wonderful for + // code where we have many case statements nested together, i.e.: + // case 1: + // case 2: + // case 3: etc. + // Handling this recursively will create a new block for each case statement + // that falls through to the next case which is IR intensive. It also causes + // deep recursion which can run into stack depth limitations. Handle + // sequential non-range case statements specially. + const CaseStmt *CurCase = &S; + const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); + + // Otherwise, iteratively add consequtive cases to this switch stmt. + while (NextCase && NextCase->getRHS() == 0) { + CurCase = NextCase; + CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext()); + SwitchInsn->addCase(llvm::ConstantInt::get(CaseVal), CaseDest); + + NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); + } + + // Normal default recursion for non-cases. + EmitStmt(CurCase->getSubStmt()); +} + +void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { + llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); + assert(DefaultBlock->empty() && + "EmitDefaultStmt: Default block already defined?"); + EmitBlock(DefaultBlock); + EmitStmt(S.getSubStmt()); +} + +void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { + llvm::Value *CondV = EmitScalarExpr(S.getCond()); + + // Handle nested switch statements. + llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; + llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; + + // Create basic block to hold stuff that comes after switch + // statement. We also need to create a default block now so that + // explicit case ranges tests can have a place to jump to on + // failure. + llvm::BasicBlock *NextBlock = createBasicBlock("sw.epilog"); + llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); + SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); + CaseRangeBlock = DefaultBlock; + + // Clear the insertion point to indicate we are in unreachable code. + Builder.ClearInsertionPoint(); + + // All break statements jump to NextBlock. If BreakContinueStack is non empty + // then reuse last ContinueBlock. + llvm::BasicBlock *ContinueBlock = 0; + if (!BreakContinueStack.empty()) + ContinueBlock = BreakContinueStack.back().ContinueBlock; + + // Ensure any vlas created between there and here, are undone + BreakContinueStack.push_back(BreakContinue(NextBlock, ContinueBlock)); + + // Emit switch body. + EmitStmt(S.getBody()); + + BreakContinueStack.pop_back(); + + // Update the default block in case explicit case range tests have + // been chained on top. + SwitchInsn->setSuccessor(0, CaseRangeBlock); + + // If a default was never emitted then reroute any jumps to it and + // discard. + if (!DefaultBlock->getParent()) { + DefaultBlock->replaceAllUsesWith(NextBlock); + delete DefaultBlock; + } + + // Emit continuation. + EmitBlock(NextBlock, true); + + SwitchInsn = SavedSwitchInsn; + CaseRangeBlock = SavedCRBlock; +} + +static std::string +SimplifyConstraint(const char *Constraint, TargetInfo &Target, + llvm::SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { + std::string Result; + + while (*Constraint) { + switch (*Constraint) { + default: + Result += Target.convertConstraint(*Constraint); + break; + // Ignore these + case '*': + case '?': + case '!': + break; + case 'g': + Result += "imr"; + break; + case '[': { + assert(OutCons && + "Must pass output names to constraints with a symbolic name"); + unsigned Index; + bool result = Target.resolveSymbolicName(Constraint, + &(*OutCons)[0], + OutCons->size(), Index); + assert(result && "Could not resolve symbolic name"); result=result; + Result += llvm::utostr(Index); + break; + } + } + + Constraint++; + } + + return Result; +} + +llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, + const TargetInfo::ConstraintInfo &Info, + const Expr *InputExpr, + std::string &ConstraintStr) { + llvm::Value *Arg; + if (Info.allowsRegister() || !Info.allowsMemory()) { + const llvm::Type *Ty = ConvertType(InputExpr->getType()); + + if (Ty->isSingleValueType()) { + Arg = EmitScalarExpr(InputExpr); + } else { + InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); + LValue Dest = EmitLValue(InputExpr); + + uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); + if (Size <= 64 && llvm::isPowerOf2_64(Size)) { + Ty = llvm::IntegerType::get(Size); + Ty = llvm::PointerType::getUnqual(Ty); + + Arg = Builder.CreateLoad(Builder.CreateBitCast(Dest.getAddress(), Ty)); + } else { + Arg = Dest.getAddress(); + ConstraintStr += '*'; + } + } + } else { + InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); + LValue Dest = EmitLValue(InputExpr); + Arg = Dest.getAddress(); + ConstraintStr += '*'; + } + + return Arg; +} + +void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { + // Analyze the asm string to decompose it into its pieces. We know that Sema + // has already done this, so it is guaranteed to be successful. + llvm::SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; + unsigned DiagOffs; + S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); + + // Assemble the pieces into the final asm string. + std::string AsmString; + for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { + if (Pieces[i].isString()) + AsmString += Pieces[i].getString(); + else if (Pieces[i].getModifier() == '\0') + AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); + else + AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + + Pieces[i].getModifier() + '}'; + } + + // Get all the output and input constraints together. + llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; + llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; + + for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { + TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), + S.getOutputName(i)); + bool result = Target.validateOutputConstraint(Info); + assert(result && "Failed to parse output constraint"); result=result; + OutputConstraintInfos.push_back(Info); + } + + for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { + TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), + S.getInputName(i)); + bool result = Target.validateInputConstraint(OutputConstraintInfos.data(), + S.getNumOutputs(), + Info); result=result; + assert(result && "Failed to parse input constraint"); + InputConstraintInfos.push_back(Info); + } + + std::string Constraints; + + std::vector<LValue> ResultRegDests; + std::vector<QualType> ResultRegQualTys; + std::vector<const llvm::Type *> ResultRegTypes; + std::vector<const llvm::Type *> ResultTruncRegTypes; + std::vector<const llvm::Type*> ArgTypes; + std::vector<llvm::Value*> Args; + + // Keep track of inout constraints. + std::string InOutConstraints; + std::vector<llvm::Value*> InOutArgs; + std::vector<const llvm::Type*> InOutArgTypes; + + for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { + TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; + + // Simplify the output constraint. + std::string OutputConstraint(S.getOutputConstraint(i)); + OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); + + const Expr *OutExpr = S.getOutputExpr(i); + OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); + + LValue Dest = EmitLValue(OutExpr); + if (!Constraints.empty()) + Constraints += ','; + + // If this is a register output, then make the inline asm return it + // by-value. If this is a memory result, return the value by-reference. + if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { + Constraints += "=" + OutputConstraint; + ResultRegQualTys.push_back(OutExpr->getType()); + ResultRegDests.push_back(Dest); + ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); + ResultTruncRegTypes.push_back(ResultRegTypes.back()); + + // If this output is tied to an input, and if the input is larger, then + // we need to set the actual result type of the inline asm node to be the + // same as the input type. + if (Info.hasMatchingInput()) { + unsigned InputNo; + for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { + TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; + if (Input.hasTiedOperand() && + Input.getTiedOperand() == i) + break; + } + assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); + + QualType InputTy = S.getInputExpr(InputNo)->getType(); + QualType OutputTy = OutExpr->getType(); + + uint64_t InputSize = getContext().getTypeSize(InputTy); + if (getContext().getTypeSize(OutputTy) < InputSize) { + // Form the asm to return the value as a larger integer type. + ResultRegTypes.back() = llvm::IntegerType::get((unsigned)InputSize); + } + } + + } else { + ArgTypes.push_back(Dest.getAddress()->getType()); + Args.push_back(Dest.getAddress()); + Constraints += "=*"; + Constraints += OutputConstraint; + } + + if (Info.isReadWrite()) { + InOutConstraints += ','; + + const Expr *InputExpr = S.getOutputExpr(i); + llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, InOutConstraints); + + if (Info.allowsRegister()) + InOutConstraints += llvm::utostr(i); + else + InOutConstraints += OutputConstraint; + + InOutArgTypes.push_back(Arg->getType()); + InOutArgs.push_back(Arg); + } + } + + unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); + + for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { + const Expr *InputExpr = S.getInputExpr(i); + + TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; + + if (!Constraints.empty()) + Constraints += ','; + + // Simplify the input constraint. + std::string InputConstraint(S.getInputConstraint(i)); + InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, + &OutputConstraintInfos); + + llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); + + // If this input argument is tied to a larger output result, extend the + // input to be the same size as the output. The LLVM backend wants to see + // the input and output of a matching constraint be the same size. Note + // that GCC does not define what the top bits are here. We use zext because + // that is usually cheaper, but LLVM IR should really get an anyext someday. + if (Info.hasTiedOperand()) { + unsigned Output = Info.getTiedOperand(); + QualType OutputTy = S.getOutputExpr(Output)->getType(); + QualType InputTy = InputExpr->getType(); + + if (getContext().getTypeSize(OutputTy) > + getContext().getTypeSize(InputTy)) { + // Use ptrtoint as appropriate so that we can do our extension. + if (isa<llvm::PointerType>(Arg->getType())) + Arg = Builder.CreatePtrToInt(Arg, + llvm::IntegerType::get(LLVMPointerWidth)); + unsigned OutputSize = (unsigned)getContext().getTypeSize(OutputTy); + Arg = Builder.CreateZExt(Arg, llvm::IntegerType::get(OutputSize)); + } + } + + + ArgTypes.push_back(Arg->getType()); + Args.push_back(Arg); + Constraints += InputConstraint; + } + + // Append the "input" part of inout constraints last. + for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { + ArgTypes.push_back(InOutArgTypes[i]); + Args.push_back(InOutArgs[i]); + } + Constraints += InOutConstraints; + + // Clobbers + for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { + std::string Clobber(S.getClobber(i)->getStrData(), + S.getClobber(i)->getByteLength()); + + Clobber = Target.getNormalizedGCCRegisterName(Clobber.c_str()); + + if (i != 0 || NumConstraints != 0) + Constraints += ','; + + Constraints += "~{"; + Constraints += Clobber; + Constraints += '}'; + } + + // Add machine specific clobbers + std::string MachineClobbers = Target.getClobbers(); + if (!MachineClobbers.empty()) { + if (!Constraints.empty()) + Constraints += ','; + Constraints += MachineClobbers; + } + + const llvm::Type *ResultType; + if (ResultRegTypes.empty()) + ResultType = llvm::Type::VoidTy; + else if (ResultRegTypes.size() == 1) + ResultType = ResultRegTypes[0]; + else + ResultType = llvm::StructType::get(ResultRegTypes); + + const llvm::FunctionType *FTy = + llvm::FunctionType::get(ResultType, ArgTypes, false); + + llvm::InlineAsm *IA = + llvm::InlineAsm::get(FTy, AsmString, Constraints, + S.isVolatile() || S.getNumOutputs() == 0); + llvm::CallInst *Result = Builder.CreateCall(IA, Args.begin(), Args.end()); + Result->addAttribute(~0, llvm::Attribute::NoUnwind); + + + // Extract all of the register value results from the asm. + std::vector<llvm::Value*> RegResults; + if (ResultRegTypes.size() == 1) { + RegResults.push_back(Result); + } else { + for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { + llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); + RegResults.push_back(Tmp); + } + } + + for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { + llvm::Value *Tmp = RegResults[i]; + + // If the result type of the LLVM IR asm doesn't match the result type of + // the expression, do the conversion. + if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { + const llvm::Type *TruncTy = ResultTruncRegTypes[i]; + // Truncate the integer result to the right size, note that + // ResultTruncRegTypes can be a pointer. + uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); + Tmp = Builder.CreateTrunc(Tmp, llvm::IntegerType::get((unsigned)ResSize)); + + if (Tmp->getType() != TruncTy) { + assert(isa<llvm::PointerType>(TruncTy)); + Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); + } + } + + EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i], + ResultRegQualTys[i]); + } +} |
