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« Last post by lerno on November 29, 2018, 02:38:19 PM »
From Clang:
void CodeGenFunction::EmitForStmt(const ForStmt &S,
ArrayRef<const Attr *> ForAttrs) {
JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
LexicalScope ForScope(*this, S.getSourceRange());
// 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);
const SourceRange &R = S.getSourceRange();
LoopStack.push(CondBlock, CGM.getContext(), ForAttrs,
SourceLocToDebugLoc(R.getBegin()),
SourceLocToDebugLoc(R.getEnd()));
// 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 cleanup scope for the condition variable cleanups.
LexicalScope ConditionScope(*this, S.getSourceRange());
if (S.getCond()) {
// If the for statement has a condition scope, emit the local variable
// declaration.
if (S.getConditionVariable()) {
EmitAutoVarDecl(*S.getConditionVariable());
}
llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
// 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.
llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
Builder.CreateCondBr(
BoolCondVal, ForBody, ExitBlock,
createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
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.
}
incrementProfileCounter(&S);
{
// 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();
EmitStopPoint(&S);
EmitBranch(CondBlock);
ForScope.ForceCleanup();
LoopStack.pop();
// Emit the fall-through block.
EmitBlock(LoopExit.getBlock(), true);
}
Here, "EmitStopPoint" is the part that emits debug information. It's in more places as well.
void CodeGenFunction::EmitStopPoint(const Stmt *S) {
if (CGDebugInfo *DI = getDebugInfo()) {
SourceLocation Loc;
Loc = S->getLocStart();
DI->EmitLocation(Builder, Loc);
LastStopPoint = Loc;
}
}
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