Implement break and continue. Patch by Anders Carlsson!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@39927 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CodeGen/CGStmt.cpp b/CodeGen/CGStmt.cpp
index 88df7d4..1e72c9d 100644
--- a/CodeGen/CGStmt.cpp
+++ b/CodeGen/CGStmt.cpp
@@ -49,6 +49,9 @@
case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break;
case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break;
+
+ case Stmt::BreakStmtClass: EmitBreakStmt(); break;
+ case Stmt::ContinueStmtClass: EmitContinueStmt(); break;
}
}
@@ -126,8 +129,6 @@
}
void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) {
- // FIXME: Handle continue/break.
-
// Emit the header for the loop, insert it, which will create an uncond br to
// it.
llvm::BasicBlock *LoopHeader = new llvm::BasicBlock("whilecond");
@@ -148,10 +149,15 @@
// As long as the condition is true, go to the loop body.
Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock);
+
+ // Store the blocks to use for break and continue.
+ BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader));
// Emit the loop body.
EmitBlock(LoopBody);
EmitStmt(S.getBody());
+
+ BreakContinueStack.pop_back();
// Cycle to the condition.
Builder.CreateBr(LoopHeader);
@@ -161,7 +167,6 @@
}
void CodeGenFunction::EmitDoStmt(const DoStmt &S) {
- // FIXME: Handle continue/break.
// TODO: "do {} while (0)" is common in macros, avoid extra blocks. Be sure
// to correctly handle break/continue though.
@@ -170,10 +175,19 @@
llvm::BasicBlock *LoopBody = new llvm::BasicBlock("dobody");
llvm::BasicBlock *AfterDo = new llvm::BasicBlock("afterdo");
EmitBlock(LoopBody);
+
+ llvm::BasicBlock *DoCond = new llvm::BasicBlock("docond");
+
+ // 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."
@@ -190,17 +204,20 @@
}
void CodeGenFunction::EmitForStmt(const ForStmt &S) {
- // FIXME: Handle continue/break.
// FIXME: What do we do if the increment (f.e.) contains a stmt expression,
// which contains a continue/break?
-
+ // TODO: We could keep track of whether the loop body contains any
+ // break/continue statements and not create unnecessary blocks (like
+ // "afterfor" for a condless loop) if it doesn't.
+
// 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 = new llvm::BasicBlock("forcond");
- llvm::BasicBlock *AfterFor = 0;
+ llvm::BasicBlock *AfterFor = new llvm::BasicBlock("afterfor");
+
EmitBlock(CondBlock);
// Evaluate the condition if present. If not, treat it as a non-zero-constant
@@ -212,7 +229,6 @@
// As long as the condition is true, iterate the loop.
llvm::BasicBlock *ForBody = new llvm::BasicBlock("forbody");
- AfterFor = new llvm::BasicBlock("afterfor");
Builder.CreateCondBr(BoolCondVal, ForBody, AfterFor);
EmitBlock(ForBody);
} else {
@@ -220,8 +236,24 @@
// 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 = new llvm::BasicBlock("forinc");
+ 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 (S.getInc())
+ EmitBlock(ContinueBlock);
// If there is an increment, emit it next.
if (S.getInc())
@@ -230,11 +262,8 @@
// Finally, branch back up to the condition for the next iteration.
Builder.CreateBr(CondBlock);
- // Emit the fall-through block if there is any.
- if (AfterFor)
- EmitBlock(AfterFor);
- else
- EmitBlock(new llvm::BasicBlock());
+ // Emit the fall-through block.
+ EmitBlock(AfterFor);
}
/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
@@ -284,3 +313,19 @@
for (const Decl *Decl = S.getDecl(); Decl; Decl = Decl->getNextDeclarator())
EmitDecl(*Decl);
}
+
+void CodeGenFunction::EmitBreakStmt() {
+ assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");
+
+ llvm::BasicBlock *Block = BreakContinueStack.back().BreakBlock;
+ Builder.CreateBr(Block);
+ EmitBlock(new llvm::BasicBlock());
+}
+
+void CodeGenFunction::EmitContinueStmt() {
+ assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
+
+ llvm::BasicBlock *Block = BreakContinueStack.back().ContinueBlock;
+ Builder.CreateBr(Block);
+ EmitBlock(new llvm::BasicBlock());
+}