Changeset af68f0a for src

Timestamp:

Apr 5, 2017, 6:07:58 PM (8 years ago)

Author:

Rob Schluntz <rschlunt@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

c51b5a3

Parents:

fbd7ad6

Message:

change all break/continue statements into goto for consistency and fix bug with labeled break

Location:

src/ControlStruct

Files:

• LabelGenerator.cc (modified) (2 diffs)
• LabelGenerator.h (modified) (2 diffs)
• MLEMutator.cc (modified) (6 diffs)

src/ControlStruct/LabelGenerator.cc

@@ -20 +20 @@
 #include "SynTree/Label.h"
 #include "SynTree/Attribute.h"
+#include "SynTree/Statement.h"
 
 namespace ControlStruct {
@@ -31 +32 @@
         }
 
-        Label LabelGenerator::newLabel( std::string suffix ) {
+        Label LabelGenerator::newLabel( std::string suffix, Statement * stmt ) {
                 std::ostringstream os;
                 os << "__L" << current++ << "__" << suffix;
+                if ( stmt && ! stmt->get_labels().empty() ) {
+                        os << "_" << stmt->get_labels().front() << "__";
+                }
                 std::string ret = os.str();
                 Label l( ret );

src/ControlStruct/LabelGenerator.h

@@ -5 +5 @@
 // file "LICENCE" distributed with Cforall.
 //
-// LabelGenerator.h -- 
+// LabelGenerator.h --
 //
 // Author           : Rodolfo G. Esteves
@@ -24 +24 @@
           public:
                 static LabelGenerator *getGenerator();
-                Label newLabel(std::string suffix = "");
+                Label newLabel(std::string suffix, Statement * stmt = nullptr);
                 void reset() { current = 0; }
                 void rewind() { current--; }

src/ControlStruct/MLEMutator.cc

@@ -56 +56 @@
                 bool labeledBlock = !(cmpndStmt->get_labels().empty());
                 if ( labeledBlock ) {
-                        Label brkLabel = generator->newLabel("blockBreak");
+                        Label brkLabel = generator->newLabel("blockBreak", cmpndStmt);
                         enclosingControlStructures.push_back( Entry( cmpndStmt, brkLabel ) );
                 } // if
@@ -80 +80 @@
                 // whether brkLabel and contLabel are used with branch statements and will recursively do the same to nested
                 // loops
-                Label brkLabel = generator->newLabel("loopBreak");
-                Label contLabel = generator->newLabel("loopContinue");
+                Label brkLabel = generator->newLabel("loopBreak", loopStmt);
+                Label contLabel = generator->newLabel("loopContinue", loopStmt);
                 enclosingControlStructures.push_back( Entry( loopStmt, brkLabel, contLabel ) );
                 loopStmt->set_body ( loopStmt->get_body()->acceptMutator( *this ) );
 
+                assert( ! enclosingControlStructures.empty() );
                 Entry &e = enclosingControlStructures.back();
                 // sanity check that the enclosing loops have been popped correctly
@@ -108 +109 @@
                 bool labeledBlock = !(ifStmt->get_labels().empty());
                 if ( labeledBlock ) {
-                        Label brkLabel = generator->newLabel("blockBreak");
+                        Label brkLabel = generator->newLabel("blockBreak", ifStmt);
                         enclosingControlStructures.push_back( Entry( ifStmt, brkLabel ) );
                 } // if
 
                 Parent::mutate( ifStmt );
-                
+
                 if ( labeledBlock ) {
                         if ( ! enclosingControlStructures.back().useBreakExit().empty() ) {
@@ -126 +127 @@
         Statement *MLEMutator::handleSwitchStmt( SwitchClass *switchStmt ) {
                 // generate a label for breaking out of a labeled switch
-                Label brkLabel = generator->newLabel("switchBreak");
+                Label brkLabel = generator->newLabel("switchBreak", switchStmt);
                 enclosingControlStructures.push_back( Entry(switchStmt, brkLabel) );
                 mutateAll( switchStmt->get_statements(), *this );
@@ -158 +159 @@
 
                 std::list< Entry >::reverse_iterator targetEntry;
-                if ( branchStmt->get_type() == BranchStmt::Goto ) {
-                        return branchStmt;
-                } else if ( branchStmt->get_type() == BranchStmt::Continue) {
-                        // continue target must be a loop
-                        if ( branchStmt->get_target() == "" ) {
-                                targetEntry = std::find_if( enclosingControlStructures.rbegin(), enclosingControlStructures.rend(), [](Entry &e) { return isLoop( e.get_controlStructure() ); } );
-                        } else {
-                                // labelled continue - lookup label in table ot find attached control structure
-                                targetEntry = std::find( enclosingControlStructures.rbegin(), enclosingControlStructures.rend(), (*targetTable)[branchStmt->get_target()] );
-                        } // if
-                        if ( targetEntry == enclosingControlStructures.rend() || ! isLoop( targetEntry->get_controlStructure() ) ) {
-                                throw SemanticError( "'continue' target must be an enclosing loop: " + originalTarget );
-                        } // if
-                } else if ( branchStmt->get_type() == BranchStmt::Break ) {
-                        if ( enclosingControlStructures.empty() ) throw SemanticError( "'break' outside a loop, switch, or labelled block" );
-                        targetEntry = enclosingControlStructures.rbegin();
-                } else {
-                        assert( false );
-                } // if
-
-                if ( branchStmt->get_target() != "" && targetTable->find( branchStmt->get_target() ) == targetTable->end() ) {
-                        throw SemanticError("The label defined in the exit loop statement does not exist: " + originalTarget );  // shouldn't happen (since that's already checked)
-                } // if
+                switch ( branchStmt->get_type() ) {
+                        case BranchStmt::Goto:
+                                return branchStmt;
+                        case BranchStmt::Continue:
+                        case BranchStmt::Break: {
+                                bool isContinue = branchStmt->get_type() == BranchStmt::Continue;
+                                // unlabeled break/continue
+                                if ( branchStmt->get_target() == "" ) {
+                                        if ( isContinue ) {
+                                                // continue target is outermost loop
+                                                targetEntry = std::find_if( enclosingControlStructures.rbegin(), enclosingControlStructures.rend(), [](Entry &e) { return isLoop( e.get_controlStructure() ); } );
+                                        } else {
+                                                // break target is outmost control structure
+                                                if ( enclosingControlStructures.empty() ) throw SemanticError( "'break' outside a loop, switch, or labelled block" );
+                                                targetEntry = enclosingControlStructures.rbegin();
+                                        } // if
+                                } else {
+                                        // labeled break/continue - lookup label in table to find attached control structure
+                                        targetEntry = std::find( enclosingControlStructures.rbegin(), enclosingControlStructures.rend(), (*targetTable)[branchStmt->get_target()] );
+                                } // if
+                                // ensure that selected target is valid
+                                if ( targetEntry == enclosingControlStructures.rend() || (isContinue && ! isLoop( targetEntry->get_controlStructure() ) ) ) {
+                                        throw SemanticError( toString( (isContinue ? "'continue'" : "'break'"), " target must be an enclosing ", (isContinue ? "loop: " : "control structure: "), originalTarget ) );
+                                } // if
+                                break;
+                        }
+                        default:
+                                assert( false );
+                } // switch
 
                 // branch error checks, get the appropriate label name and create a goto
@@ -197 +204 @@
                 } // switch
 
-                if ( branchStmt->get_target() == "" && branchStmt->get_type() != BranchStmt::Continue ) {
-                        // unlabelled break/continue - can keep branch as break/continue for extra semantic information, but add
-                        // exitLabel as its destination so that label passes can easily determine where the break/continue goes to
-                        branchStmt->set_target( exitLabel );
-                        return branchStmt;
-                } else {
-                        // labelled break/continue - can't easily emulate this with break and continue, so transform into a goto
-                        delete branchStmt;
-                        return new BranchStmt( std::list<Label>(), exitLabel, BranchStmt::Goto );
-                } // if
+                // transform break/continue statements into goto to simplify later handling of branches
+                delete branchStmt;
+                return new BranchStmt( std::list<Label>(), exitLabel, BranchStmt::Goto );
         }