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llvm-project/clang/lib/CodeGen/CGStmt.cpp

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//===--- 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 "CodeGenFunction.h"
#include "CGDebugInfo.h"
#include "CodeGenModule.h"
#include "TargetInfo.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "clang/Basic/PrettyStackTrace.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Support/CallSite.h"
using namespace clang;
using namespace CodeGen;
//===----------------------------------------------------------------------===//
// Statement Emission
//===----------------------------------------------------------------------===//
void CodeGenFunction::EmitStopPoint(const Stmt *S) {
if (CGDebugInfo *DI = getDebugInfo()) {
SourceLocation Loc;
Loc = S->getLocStart();
DI->EmitLocation(Builder, Loc);
LastStopPoint = Loc;
}
}
void CodeGenFunction::EmitStmt(const Stmt *S) {
assert(S && "Null statement?");
// These statements have their own debug info handling.
if (EmitSimpleStmt(S))
return;
// Check if we are generating unreachable code.
if (!HaveInsertPoint()) {
// If so, and the statement doesn't contain a label, then we do not need to
// generate actual code. This is safe because (1) the current point is
// unreachable, so we don't need to execute the code, and (2) we've already
// handled the statements which update internal data structures (like the
// local variable map) which could be used by subsequent statements.
if (!ContainsLabel(S)) {
// Verify that any decl statements were handled as simple, they may be in
// scope of subsequent reachable statements.
assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
return;
}
// Otherwise, make a new block to hold the code.
EnsureInsertPoint();
}
// Generate a stoppoint if we are emitting debug info.
EmitStopPoint(S);
switch (S->getStmtClass()) {
case Stmt::NoStmtClass:
case Stmt::CXXCatchStmtClass:
case Stmt::SEHExceptStmtClass:
case Stmt::SEHFinallyStmtClass:
case Stmt::MSDependentExistsStmtClass:
case Stmt::OMPParallelDirectiveClass:
llvm_unreachable("invalid statement class to emit generically");
case Stmt::NullStmtClass:
case Stmt::CompoundStmtClass:
case Stmt::DeclStmtClass:
case Stmt::LabelStmtClass:
case Stmt::AttributedStmtClass:
case Stmt::GotoStmtClass:
case Stmt::BreakStmtClass:
case Stmt::ContinueStmtClass:
case Stmt::DefaultStmtClass:
case Stmt::CaseStmtClass:
llvm_unreachable("should have emitted these statements as simple");
#define STMT(Type, Base)
#define ABSTRACT_STMT(Op)
#define EXPR(Type, Base) \
case Stmt::Type##Class:
#include "clang/AST/StmtNodes.inc"
{
// Remember the block we came in on.
llvm::BasicBlock *incoming = Builder.GetInsertBlock();
assert(incoming && "expression emission must have an insertion point");
EmitIgnoredExpr(cast<Expr>(S));
llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
assert(outgoing && "expression emission cleared block!");
// The expression emitters assume (reasonably!) that the insertion
// point is always set. To maintain that, the call-emission code
// for noreturn functions has to enter a new block with no
// predecessors. We want to kill that block and mark the current
// insertion point unreachable in the common case of a call like
// "exit();". Since expression emission doesn't otherwise create
// blocks with no predecessors, we can just test for that.
// However, we must be careful not to do this to our incoming
// block, because *statement* emission does sometimes create
// reachable blocks which will have no predecessors until later in
// the function. This occurs with, e.g., labels that are not
// reachable by fallthrough.
if (incoming != outgoing && outgoing->use_empty()) {
outgoing->eraseFromParent();
Builder.ClearInsertionPoint();
}
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::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break;
case Stmt::GCCAsmStmtClass: // Intentional fall-through.
case Stmt::MSAsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break;
case Stmt::CapturedStmtClass:
EmitCapturedStmt(cast<CapturedStmt>(*S), CR_Default);
break;
case Stmt::ObjCAtTryStmtClass:
EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
break;
case Stmt::ObjCAtCatchStmtClass:
llvm_unreachable(
"@catch statements should be handled by EmitObjCAtTryStmt");
case Stmt::ObjCAtFinallyStmtClass:
llvm_unreachable(
"@finally statements should be handled by EmitObjCAtTryStmt");
case Stmt::ObjCAtThrowStmtClass:
EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
break;
case Stmt::ObjCAtSynchronizedStmtClass:
EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
break;
case Stmt::ObjCForCollectionStmtClass:
EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
break;
case Stmt::ObjCAutoreleasePoolStmtClass:
EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
break;
case Stmt::CXXTryStmtClass:
EmitCXXTryStmt(cast<CXXTryStmt>(*S));
break;
case Stmt::CXXForRangeStmtClass:
EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S));
case Stmt::SEHTryStmtClass:
// FIXME Not yet implemented
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::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break;
case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break;
case Stmt::AttributedStmtClass:
EmitAttributedStmt(cast<AttributedStmt>(*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).
llvm::Value* CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
AggValueSlot AggSlot) {
PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
"LLVM IR generation of compound statement ('{}')");
// Keep track of the current cleanup stack depth, including debug scopes.
LexicalScope Scope(*this, S.getSourceRange());
return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
}
llvm::Value*
CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
bool GetLast,
AggValueSlot AggSlot) {
for (CompoundStmt::const_body_iterator I = S.body_begin(),
E = S.body_end()-GetLast; I != E; ++I)
EmitStmt(*I);
llvm::Value *RetAlloca = 0;
if (GetLast) {
// 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->getDecl());
LastStmt = LS->getSubStmt();
}
EnsureInsertPoint();
QualType ExprTy = cast<Expr>(LastStmt)->getType();
if (hasAggregateEvaluationKind(ExprTy)) {
EmitAggExpr(cast<Expr>(LastStmt), AggSlot);
} else {
// We can't return an RValue here because there might be cleanups at
// the end of the StmtExpr. Because of that, we have to emit the result
// here into a temporary alloca.
RetAlloca = CreateMemTemp(ExprTy);
EmitAnyExprToMem(cast<Expr>(LastStmt), RetAlloca, Qualifiers(),
/*IsInit*/false);
}
}
return RetAlloca;
}
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 (!EHStack.empty())
return;
// Can only simplify direct branches.
if (!BI || !BI->isUnconditional())
return;
// Can only simplify empty blocks.
if (BI != BB->begin())
return;
BB->replaceAllUsesWith(BI->getSuccessor(0));
BI->eraseFromParent();
BB->eraseFromParent();
}
void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
// Fall out of the current block (if necessary).
EmitBranch(BB);
if (IsFinished && BB->use_empty()) {
delete BB;
return;
}
// Place the block after the current block, if possible, or else at
// the end of the function.
if (CurBB && CurBB->getParent())
CurFn->getBasicBlockList().insertAfter(CurBB, BB);
else
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::EmitBlockAfterUses(llvm::BasicBlock *block) {
bool inserted = false;
for (llvm::BasicBlock::use_iterator
i = block->use_begin(), e = block->use_end(); i != e; ++i) {
if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(*i)) {
CurFn->getBasicBlockList().insertAfter(insn->getParent(), block);
inserted = true;
break;
}
}
if (!inserted)
CurFn->getBasicBlockList().push_back(block);
Builder.SetInsertPoint(block);
}
CodeGenFunction::JumpDest
CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
JumpDest &Dest = LabelMap[D];
if (Dest.isValid()) return Dest;
// Create, but don't insert, the new block.
Dest = JumpDest(createBasicBlock(D->getName()),
EHScopeStack::stable_iterator::invalid(),
NextCleanupDestIndex++);
return Dest;
}
void CodeGenFunction::EmitLabel(const LabelDecl *D) {
// Add this label to the current lexical scope if we're within any
// normal cleanups. Jumps "in" to this label --- when permitted by
// the language --- may need to be routed around such cleanups.
if (EHStack.hasNormalCleanups() && CurLexicalScope)
CurLexicalScope->addLabel(D);
JumpDest &Dest = LabelMap[D];
// If we didn't need a forward reference to this label, just go
// ahead and create a destination at the current scope.
if (!Dest.isValid()) {
Dest = getJumpDestInCurrentScope(D->getName());
// Otherwise, we need to give this label a target depth and remove
// it from the branch-fixups list.
} else {
assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
Dest.setScopeDepth(EHStack.stable_begin());
ResolveBranchFixups(Dest.getBlock());
}
EmitBlock(Dest.getBlock());
}
/// Change the cleanup scope of the labels in this lexical scope to
/// match the scope of the enclosing context.
void CodeGenFunction::LexicalScope::rescopeLabels() {
assert(!Labels.empty());
EHScopeStack::stable_iterator innermostScope
= CGF.EHStack.getInnermostNormalCleanup();
// Change the scope depth of all the labels.
for (SmallVectorImpl<const LabelDecl*>::const_iterator
i = Labels.begin(), e = Labels.end(); i != e; ++i) {
assert(CGF.LabelMap.count(*i));
JumpDest &dest = CGF.LabelMap.find(*i)->second;
assert(dest.getScopeDepth().isValid());
assert(innermostScope.encloses(dest.getScopeDepth()));
dest.setScopeDepth(innermostScope);
}
// Reparent the labels if the new scope also has cleanups.
if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
ParentScope->Labels.append(Labels.begin(), Labels.end());
}
}
void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
EmitLabel(S.getDecl());
EmitStmt(S.getSubStmt());
}
void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &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(getJumpDestForLabel(S.getLabel()));
}
void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
if (const LabelDecl *Target = S.getConstantTarget()) {
EmitBranchThroughCleanup(getJumpDestForLabel(Target));
return;
}
// Ensure that we have an i8* for our PHI node.
llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
Int8PtrTy, "addr");
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
// Get the basic block for the indirect goto.
llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
// The first instruction in the block has to be the PHI for the switch dest,
// add an entry for this branch.
cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
EmitBranch(IndGotoBB);
}
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.
LexicalScope ConditionScope(*this, S.getSourceRange());
if (S.getConditionVariable())
EmitAutoVarDecl(*S.getConditionVariable());
// If the condition constant folds and can be elided, try to avoid emitting
// the condition and the dead arm of the if/else.
bool CondConstant;
if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) {
// Figure out which block (then or else) is executed.
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.
// This avoids emitting dead code and simplifies the CFG substantially.
if (!ContainsLabel(Skipped)) {
if (Executed) {
RunCleanupsScope ExecutedScope(*this);
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);
{
RunCleanupsScope ThenScope(*this);
EmitStmt(S.getThen());
}
EmitBranch(ContBlock);
// 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);
}
// Emit the continuation block for code after the if.
EmitBlock(ContBlock, true);
}
void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) {
// Emit the header for the loop, which will also become
// the continue target.
JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
EmitBlock(LoopHeader.getBlock());
// Create an exit block for when the condition fails, which will
// also become the break target.
JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
// Store the blocks to use for break and continue.
BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));
// C++ [stmt.while]p2:
// When the condition of a while statement is a declaration, the
// scope of the variable that is declared extends from its point
// of declaration (3.3.2) to the end of the while statement.
// [...]
// The object created in a condition is destroyed and created
// with each iteration of the loop.
RunCleanupsScope ConditionScope(*this);
if (S.getConditionVariable())
EmitAutoVarDecl(*S.getConditionVariable());
// 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.
llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
if (EmitBoolCondBranch) {
llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
if (ConditionScope.requiresCleanups())
ExitBlock = createBasicBlock("while.exit");
Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock);
if (ExitBlock != LoopExit.getBlock()) {
EmitBlock(ExitBlock);
EmitBranchThroughCleanup(LoopExit);
}
}
// Emit the loop body. We have to emit this in a cleanup scope
// because it might be a singleton DeclStmt.
{
RunCleanupsScope BodyScope(*this);
EmitBlock(LoopBody);
EmitStmt(S.getBody());
}
BreakContinueStack.pop_back();
// Immediately force cleanup.
ConditionScope.ForceCleanup();
// Branch to the loop header again.
EmitBranch(LoopHeader.getBlock());
// Emit the exit block.
EmitBlock(LoopExit.getBlock(), true);
// The LoopHeader typically is just a branch if we skipped emitting
// a branch, try to erase it.
if (!EmitBoolCondBranch)
SimplifyForwardingBlocks(LoopHeader.getBlock());
}
void CodeGenFunction::EmitDoStmt(const DoStmt &S) {
JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");
// Store the blocks to use for break and continue.
BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));
// Emit the body of the loop.
llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
EmitBlock(LoopBody);
{
RunCleanupsScope BodyScope(*this);
EmitStmt(S.getBody());
}
BreakContinueStack.pop_back();
EmitBlock(LoopCond.getBlock());
// 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, LoopExit.getBlock());
// Emit the exit block.
EmitBlock(LoopExit.getBlock());
// The DoCond block typically is just a branch if we skipped
// emitting a branch, try to erase it.
if (!EmitBoolCondBranch)
SimplifyForwardingBlocks(LoopCond.getBlock());
}
void CodeGenFunction::EmitForStmt(const ForStmt &S) {
JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
RunCleanupsScope ForScope(*this);
CGDebugInfo *DI = getDebugInfo();
if (DI)
DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin());
// Evaluate the first part before the loop.
if (S.getInit())
EmitStmt(S.getInit());
// Start the loop with a block that tests the condition.
// If there's an increment, the continue scope will be overwritten
// later.
JumpDest Continue = getJumpDestInCurrentScope("for.cond");
llvm::BasicBlock *CondBlock = Continue.getBlock();
EmitBlock(CondBlock);
// Create a cleanup scope for the condition variable cleanups.
RunCleanupsScope ConditionScope(*this);
llvm::Value *BoolCondVal = 0;
if (S.getCond()) {
// If the for statement has a condition scope, emit the local variable
// declaration.
llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
if (S.getConditionVariable()) {
EmitAutoVarDecl(*S.getConditionVariable());
}
// If there are any cleanups between here and the loop-exit scope,
// create a block to stage a loop exit along.
if (ForScope.requiresCleanups())
ExitBlock = createBasicBlock("for.cond.cleanup");
// 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.
BoolCondVal = EvaluateExprAsBool(S.getCond());
Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock);
if (ExitBlock != LoopExit.getBlock()) {
EmitBlock(ExitBlock);
EmitBranchThroughCleanup(LoopExit);
}
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. Otherwise we'll need to create
// a block for it (in the current scope, i.e. in the scope of the
// condition), and that we will become our continue block.
if (S.getInc())
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 body, in case it is not
// a compound statement.
RunCleanupsScope BodyScope(*this);
EmitStmt(S.getBody());
}
// If there is an increment, emit it next.
if (S.getInc()) {
EmitBlock(Continue.getBlock());
EmitStmt(S.getInc());
}
BreakContinueStack.pop_back();
ConditionScope.ForceCleanup();
EmitBranch(CondBlock);
ForScope.ForceCleanup();
if (DI)
DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd());
// Emit the fall-through block.
EmitBlock(LoopExit.getBlock(), true);
}
void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) {
JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
RunCleanupsScope ForScope(*this);
CGDebugInfo *DI = getDebugInfo();
if (DI)
DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin());
// 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->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd());
// Emit the fall-through block.
EmitBlock(LoopExit.getBlock(), 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 {
EmitStoreOfComplex(RV.getComplexVal(),
MakeNaturalAlignAddrLValue(ReturnValue, Ty),
/*init*/ true);
}
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();
// Treat block literals in a return expression as if they appeared
// in their own scope. This permits a small, easily-implemented
// exception to our over-conservative rules about not jumping to
// statements following block literals with non-trivial cleanups.
RunCleanupsScope cleanupScope(*this);
if (const ExprWithCleanups *cleanups =
dyn_cast_or_null<ExprWithCleanups>(RV)) {
enterFullExpression(cleanups);
RV = cleanups->getSubExpr();
}
// FIXME: Clean this up by using an LValue for ReturnTemp,
// EmitStoreThroughLValue, and EmitAnyExpr.
if (S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable()) {
// Apply the named return value optimization for this return statement,
// which means doing nothing: the appropriate result has already been
// constructed into the NRVO variable.
// If there is an NRVO flag for this variable, set it to 1 into indicate
// that the cleanup code should not destroy the variable.
if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
Builder.CreateStore(Builder.getTrue(), NRVOFlag);
} else 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.
RValue Result = EmitReferenceBindingToExpr(RV);
Builder.CreateStore(Result.getScalarVal(), ReturnValue);
} else {
switch (getEvaluationKind(RV->getType())) {
case TEK_Scalar:
Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
break;
case TEK_Complex:
EmitComplexExprIntoLValue(RV,
MakeNaturalAlignAddrLValue(ReturnValue, RV->getType()),
/*isInit*/ true);
break;
case TEK_Aggregate: {
CharUnits Alignment = getContext().getTypeAlignInChars(RV->getType());
EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Alignment,
Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased));
break;
}
}
}
++NumReturnExprs;
if (RV == 0 || RV->isEvaluatable(getContext()))
++NumSimpleReturnExprs;
cleanupScope.ForceCleanup();
EmitBranchThroughCleanup(ReturnBlock);
}
void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
// As long as debug info is modeled with instructions, we have to ensure we
// have a place to insert here and write the stop point here.
if (HaveInsertPoint())
EmitStopPoint(&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);
JumpDest 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);
JumpDest 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()->EvaluateKnownConstInt(getContext());
llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(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(Builder.getInt(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(), Builder.getInt(LHS));
llvm::Value *Cond =
Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
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 there is no enclosing switch instance that we're aware of, then this
// case statement and its block can be elided. This situation only happens
// when we've constant-folded the switch, are emitting the constant case,
// and part of the constant case includes another case statement. For
// instance: switch (4) { case 4: do { case 5: } while (1); }
if (!SwitchInsn) {
EmitStmt(S.getSubStmt());
return;
}
// Handle case ranges.
if (S.getRHS()) {
EmitCaseStmtRange(S);
return;
}
llvm::ConstantInt *CaseVal =
Builder.getInt(S.getLHS()->EvaluateKnownConstInt(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 ((CGM.getCodeGenOpts().OptimizationLevel > 0) &&
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();
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.:
// 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 consecutive cases to this switch stmt.
while (NextCase && NextCase->getRHS() == 0) {
CurCase = NextCase;
llvm::ConstantInt *CaseVal =
Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));
SwitchInsn->addCase(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());
}
/// 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,
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::APSInt &ConstantCondValue,
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()->EvaluateKnownConstInt(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");
RunCleanupsScope ConditionScope(*this);
if (S.getConditionVariable())
EmitAutoVarDecl(*S.getConditionVariable());
// Handle nested switch statements.
llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
// 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::APSInt ConstantCondValue;
if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
SmallVector<const Stmt*, 4> CaseStmts;
if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
getContext())) {
RunCleanupsScope ExecutedScope(*this);
// At this point, we are no longer "within" a switch instance, so
// we can temporarily enforce this to ensure that any embedded case
// statements are not emitted.
SwitchInsn = 0;
// 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]);
// Now we want to restore the saved switch instance so that nested
// switches continue to function properly
SwitchInsn = SavedSwitchInsn;
return;
}
}
llvm::Value *CondV = EmitScalarExpr(S.getCond());
// 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 *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.
JumpDest OuterContinue;
if (!BreakContinueStack.empty())
OuterContinue = BreakContinueStack.back().ContinueBlock;
BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));
// 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->setDefaultDest(CaseRangeBlock);
// If a default was never emitted:
if (!DefaultBlock->getParent()) {
// If we have cleanups, emit the default block so that there's a
// place to jump through the cleanups from.
if (ConditionScope.requiresCleanups()) {
EmitBlock(DefaultBlock);
// Otherwise, just forward the default block to the switch end.
} else {
DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
delete DefaultBlock;
}
}
ConditionScope.ForceCleanup();
// Emit continuation.
EmitBlock(SwitchExit.getBlock(), true);
SwitchInsn = SavedSwitchInsn;
CaseRangeBlock = SavedCRBlock;
}
static std::string
SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) {
std::string Result;
while (*Constraint) {
switch (*Constraint) {
default:
Result += Target.convertConstraint(Constraint);
break;
// Ignore these
case '*':
case '?':
case '!':
case '=': // Will see this and the following in mult-alt constraints.
case '+':
break;
case '#': // Ignore the rest of the constraint alternative.
while (Constraint[1] && Constraint[1] != ',')
Constraint++;
break;
case ',':
Result += "|";
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"); (void)result;
Result += llvm::utostr(Index);
break;
}
}
Constraint++;
}
return Result;
}
/// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
/// as using a particular register add that as a constraint that will be used
/// in this asm stmt.
static std::string
AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
const TargetInfo &Target, CodeGenModule &CGM,
const AsmStmt &Stmt) {
const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
if (!AsmDeclRef)
return Constraint;
const ValueDecl &Value = *AsmDeclRef->getDecl();
const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
if (!Variable)
return Constraint;
if (Variable->getStorageClass() != SC_Register)
return Constraint;
AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
if (!Attr)
return Constraint;
StringRef Register = Attr->getLabel();
assert(Target.isValidGCCRegisterName(Register));
// We're using validateOutputConstraint here because we only care if
// this is a register constraint.
TargetInfo::ConstraintInfo Info(Constraint, "");
if (Target.validateOutputConstraint(Info) &&
!Info.allowsRegister()) {
CGM.ErrorUnsupported(&Stmt, "__asm__");
return Constraint;
}
// Canonicalize the register here before returning it.
Register = Target.getNormalizedGCCRegisterName(Register);
return "{" + Register.str() + "}";
}
llvm::Value*
CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info,
LValue InputValue, QualType InputType,
std::string &ConstraintStr) {
llvm::Value *Arg;
if (Info.allowsRegister() || !Info.allowsMemory()) {
if (CodeGenFunction::hasScalarEvaluationKind(InputType)) {
Arg = EmitLoadOfLValue(InputValue).getScalarVal();
} else {
llvm::Type *Ty = ConvertType(InputType);
uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
if (Size <= 64 && llvm::isPowerOf2_64(Size)) {
Ty = llvm::IntegerType::get(getLLVMContext(), Size);
Ty = llvm::PointerType::getUnqual(Ty);
Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(),
Ty));
} else {
Arg = InputValue.getAddress();
ConstraintStr += '*';
}
}
} else {
Arg = InputValue.getAddress();
ConstraintStr += '*';
}
return Arg;
}
llvm::Value* CodeGenFunction::EmitAsmInput(
const TargetInfo::ConstraintInfo &Info,
const Expr *InputExpr,
std::string &ConstraintStr) {
if (Info.allowsRegister() || !Info.allowsMemory())
if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
return EmitScalarExpr(InputExpr);
InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
LValue Dest = EmitLValue(InputExpr);
return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr);
}
/// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
/// asm call instruction. The !srcloc MDNode contains a list of constant
/// integers which are the source locations of the start of each line in the
/// asm.
static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
CodeGenFunction &CGF) {
SmallVector<llvm::Value *, 8> Locs;
// Add the location of the first line to the MDNode.
Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty,
Str->getLocStart().getRawEncoding()));
StringRef StrVal = Str->getString();
if (!StrVal.empty()) {
const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
const LangOptions &LangOpts = CGF.CGM.getLangOpts();
// Add the location of the start of each subsequent line of the asm to the
// MDNode.
for (unsigned i = 0, e = StrVal.size()-1; i != e; ++i) {
if (StrVal[i] != '\n') continue;
SourceLocation LineLoc = Str->getLocationOfByte(i+1, SM, LangOpts,
CGF.getTarget());
Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty,
LineLoc.getRawEncoding()));
}
}
return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
}
void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
// Assemble the final asm string.
std::string AsmString = S.generateAsmString(getContext());
// Get all the output and input constraints together.
SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
StringRef Name;
if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
Name = GAS->getOutputName(i);
TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
assert(IsValid && "Failed to parse output constraint");
OutputConstraintInfos.push_back(Info);
}
for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
StringRef Name;
if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
Name = GAS->getInputName(i);
TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
bool IsValid =
getTarget().validateInputConstraint(OutputConstraintInfos.data(),
S.getNumOutputs(), Info);
assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
InputConstraintInfos.push_back(Info);
}
std::string Constraints;
std::vector<LValue> ResultRegDests;
std::vector<QualType> ResultRegQualTys;
std::vector<llvm::Type *> ResultRegTypes;
std::vector<llvm::Type *> ResultTruncRegTypes;
std::vector<llvm::Type *> ArgTypes;
std::vector<llvm::Value*> Args;
// Keep track of inout constraints.
std::string InOutConstraints;
std::vector<llvm::Value*> InOutArgs;
std::vector<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,
getTarget());
const Expr *OutExpr = S.getOutputExpr(i);
OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
getTarget(), CGM, S);
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() && hasScalarEvaluationKind(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 OutputType = OutExpr->getType();
uint64_t InputSize = getContext().getTypeSize(InputTy);
if (getContext().getTypeSize(OutputType) < InputSize) {
// Form the asm to return the value as a larger integer or fp type.
ResultRegTypes.back() = ConvertType(InputTy);
}
}
if (llvm::Type* AdjTy =
getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
ResultRegTypes.back()))
ResultRegTypes.back() = AdjTy;
else {
CGM.getDiags().Report(S.getAsmLoc(),
diag::err_asm_invalid_type_in_input)
<< OutExpr->getType() << OutputConstraint;
}
} 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 = EmitAsmInputLValue(Info, Dest, InputExpr->getType(),
InOutConstraints);
if (llvm::Type* AdjTy =
getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
Arg->getType()))
Arg = Builder.CreateBitCast(Arg, AdjTy);
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(), getTarget(),
&OutputConstraintInfos);
InputConstraint =
AddVariableConstraints(InputConstraint,
*InputExpr->IgnoreParenNoopCasts(getContext()),
getTarget(), CGM, S);
llvm::Value *Arg = EmitAsmInput(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 OutputType = S.getOutputExpr(Output)->getType();
QualType InputTy = InputExpr->getType();
if (getContext().getTypeSize(OutputType) >
getContext().getTypeSize(InputTy)) {
// Use ptrtoint as appropriate so that we can do our extension.
if (isa<llvm::PointerType>(Arg->getType()))
Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
llvm::Type *OutputTy = ConvertType(OutputType);
if (isa<llvm::IntegerType>(OutputTy))
Arg = Builder.CreateZExt(Arg, OutputTy);
else if (isa<llvm::PointerType>(OutputTy))
Arg = Builder.CreateZExt(Arg, IntPtrTy);
else {
assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
Arg = Builder.CreateFPExt(Arg, OutputTy);
}
}
}
if (llvm::Type* AdjTy =
getTargetHooks().adjustInlineAsmType(*this, InputConstraint,
Arg->getType()))
Arg = Builder.CreateBitCast(Arg, AdjTy);
else
CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
<< InputExpr->getType() << InputConstraint;
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++) {
StringRef Clobber = S.getClobber(i);
if (Clobber != "memory" && Clobber != "cc")
Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
if (i != 0 || NumConstraints != 0)
Constraints += ',';
Constraints += "~{";
Constraints += Clobber;
Constraints += '}';
}
// Add machine specific clobbers
std::string MachineClobbers = getTarget().getClobbers();
if (!MachineClobbers.empty()) {
if (!Constraints.empty())
Constraints += ',';
Constraints += MachineClobbers;
}
llvm::Type *ResultType;
if (ResultRegTypes.empty())
ResultType = VoidTy;
else if (ResultRegTypes.size() == 1)
ResultType = ResultRegTypes[0];
else
ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
llvm::FunctionType *FTy =
llvm::FunctionType::get(ResultType, ArgTypes, false);
bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
llvm::InlineAsm *IA =
llvm::InlineAsm::get(FTy, AsmString, Constraints, HasSideEffect,
/* IsAlignStack */ false, AsmDialect);
llvm::CallInst *Result = Builder.CreateCall(IA, Args);
Result->addAttribute(llvm::AttributeSet::FunctionIndex,
llvm::Attribute::NoUnwind);
// Slap the source location of the inline asm into a !srcloc metadata on the
// call. FIXME: Handle metadata for MS-style inline asms.
if (const GCCAsmStmt *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
Result->setMetadata("srcloc", getAsmSrcLocInfo(gccAsmStmt->getAsmString(),
*this));
// 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]) {
llvm::Type *TruncTy = ResultTruncRegTypes[i];
// Truncate the integer result to the right size, note that TruncTy can be
// a pointer.
if (TruncTy->isFloatingPointTy())
Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
Tmp = Builder.CreateTrunc(Tmp,
llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
} else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
Tmp = Builder.CreatePtrToInt(Tmp,
llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
Tmp = Builder.CreateTrunc(Tmp, TruncTy);
} else if (TruncTy->isIntegerTy()) {
Tmp = Builder.CreateTrunc(Tmp, TruncTy);
} else if (TruncTy->isVectorTy()) {
Tmp = Builder.CreateBitCast(Tmp, TruncTy);
}
}
EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]);
}
}
static LValue InitCapturedStruct(CodeGenFunction &CGF, const CapturedStmt &S) {
const RecordDecl *RD = S.getCapturedRecordDecl();
QualType RecordTy = CGF.getContext().getRecordType(RD);
// Initialize the captured struct.
LValue SlotLV = CGF.MakeNaturalAlignAddrLValue(
CGF.CreateMemTemp(RecordTy, "agg.captured"), RecordTy);
RecordDecl::field_iterator CurField = RD->field_begin();
for (CapturedStmt::capture_init_iterator I = S.capture_init_begin(),
E = S.capture_init_end();
I != E; ++I, ++CurField) {
LValue LV = CGF.EmitLValueForFieldInitialization(SlotLV, *CurField);
CGF.EmitInitializerForField(*CurField, LV, *I, ArrayRef<VarDecl *>());
}
return SlotLV;
}
/// Generate an outlined function for the body of a CapturedStmt, store any
/// captured variables into the captured struct, and call the outlined function.
llvm::Function *
CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
const CapturedDecl *CD = S.getCapturedDecl();
const RecordDecl *RD = S.getCapturedRecordDecl();
assert(CD->hasBody() && "missing CapturedDecl body");
LValue CapStruct = InitCapturedStruct(*this, S);
// Emit the CapturedDecl
CodeGenFunction CGF(CGM, true);
CGF.CapturedStmtInfo = new CGCapturedStmtInfo(S, K);
llvm::Function *F = CGF.GenerateCapturedStmtFunction(CD, RD);
delete CGF.CapturedStmtInfo;
// Emit call to the helper function.
EmitCallOrInvoke(F, CapStruct.getAddress());
return F;
}
/// Creates the outlined function for a CapturedStmt.
llvm::Function *
CodeGenFunction::GenerateCapturedStmtFunction(const CapturedDecl *CD,
const RecordDecl *RD) {
assert(CapturedStmtInfo &&
"CapturedStmtInfo should be set when generating the captured function");
// Check if we should generate debug info for this function.
maybeInitializeDebugInfo();
// Build the argument list.
ASTContext &Ctx = CGM.getContext();
FunctionArgList Args;
Args.append(CD->param_begin(), CD->param_end());
// Create the function declaration.
FunctionType::ExtInfo ExtInfo;
const CGFunctionInfo &FuncInfo =
CGM.getTypes().arrangeFunctionDeclaration(Ctx.VoidTy, Args, ExtInfo,
/*IsVariadic=*/false);
llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);
llvm::Function *F =
llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
CapturedStmtInfo->getHelperName(), &CGM.getModule());
CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
// Generate the function.
StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getBody()->getLocStart());
// Set the context parameter in CapturedStmtInfo.
llvm::Value *DeclPtr = LocalDeclMap[CD->getContextParam()];
assert(DeclPtr && "missing context parameter for CapturedStmt");
CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));
// If 'this' is captured, load it into CXXThisValue.
if (CapturedStmtInfo->isCXXThisExprCaptured()) {
FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
LValue LV = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
Ctx.getTagDeclType(RD));
LValue ThisLValue = EmitLValueForField(LV, FD);
CXXThisValue = EmitLoadOfLValue(ThisLValue).getScalarVal();
}
CapturedStmtInfo->EmitBody(*this, CD->getBody());
FinishFunction(CD->getBodyRBrace());
return F;
}
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