Changes in src/ControlStruct/MLEMutator.cc [994ec2c:e39aa0f]

File:

• src/ControlStruct/MLEMutator.cc (modified) (17 diffs)

src/ControlStruct/MLEMutator.cc

@@ -5 +5 @@
 // file "LICENCE" distributed with Cforall.
 //
-// MLEMutator.cc -- 
+// MLEMutator.cc --
 //
 // Author           : Rodolfo G. Esteves
@@ -14 +14 @@
 //
 
-// NOTE: There are two known subtle differences from the code that uC++ 
+// NOTE: There are two known subtle differences from the code that uC++
 // generates for the same input
 // -CFA puts the break label inside at the end of a switch, uC++ puts it after
@@ -27 +27 @@
 #include "SynTree/Statement.h"
 #include "SynTree/Expression.h"
+#include "SynTree/Attribute.h"
 
 namespace ControlStruct {
@@ -33 +34 @@
                 targetTable = 0;
         }
-
-        // break labels have to come after the statement they break out of, 
+        namespace {
+                Statement * isLoop( Statement * stmt ) { return dynamic_cast< WhileStmt * >( stmt ) ? stmt : dynamic_cast< ForStmt * >( stmt ) ? stmt : 0; }
+        }
+
+        // break labels have to come after the statement they break out of,
         // so mutate a statement, then if they inform us through the breakLabel field
-        // tha they need a place to jump to on a break statement, add the break label 
+        // tha they need a place to jump to on a break statement, add the break label
         // to the body of statements
         void MLEMutator::fixBlock( std::list< Statement * > &kids ) {
@@ -44 +48 @@
                         if ( ! get_breakLabel().empty() ) {
                                 std::list< Statement * >::iterator next = k+1;
-                                if ( next == kids.end() ) {
-                                        std::list<Label> ls; ls.push_back( get_breakLabel() );
-                                        kids.push_back( new NullStmt( ls ) );
-                                } else {
-                                        (*next)->get_labels().push_back( get_breakLabel() );
-                                }
-
+                                std::list<Label> ls; ls.push_back( get_breakLabel() );
+                                kids.insert( next, new NullStmt( ls ) );
                                 set_breakLabel("");
                         } // if
@@ -60 +59 @@
                 if ( labeledBlock ) {
                         Label brkLabel = generator->newLabel("blockBreak");
-                        enclosingBlocks.push_back( Entry( cmpndStmt, brkLabel ) );
+                        enclosingControlStructures.push_back( Entry( cmpndStmt, brkLabel ) );
                 } // if
 
@@ -69 +68 @@
 
                 if ( labeledBlock ) {
-                        assert( ! enclosingBlocks.empty() );
-                        if ( ! enclosingBlocks.back().useBreakExit().empty() ) {
-                                set_breakLabel( enclosingBlocks.back().useBreakExit() );
-                        }
-                        enclosingBlocks.pop_back();
+                        assert( ! enclosingControlStructures.empty() );
+                        if ( ! enclosingControlStructures.back().useBreakExit().empty() ) {
+                                set_breakLabel( enclosingControlStructures.back().useBreakExit() );
+                        }
+                        enclosingControlStructures.pop_back();
                 } // if
 
@@ -81 +80 @@
         template< typename LoopClass >
         Statement *MLEMutator::handleLoopStmt( LoopClass *loopStmt ) {
-                // remember this as the most recent enclosing loop, then mutate 
+                // remember this as the most recent enclosing loop, then mutate
                 // the body of the loop -- this will determine whether brkLabel
                 // and contLabel are used with branch statements
@@ -87 +86 @@
                 Label brkLabel = generator->newLabel("loopBreak");
                 Label contLabel = generator->newLabel("loopContinue");
-                enclosingLoops.push_back( Entry( loopStmt, brkLabel, contLabel ) );
+                enclosingControlStructures.push_back( Entry( loopStmt, brkLabel, contLabel ) );
                 loopStmt->set_body ( loopStmt->get_body()->acceptMutator( *this ) );
 
                 // sanity check that the enclosing loops have been popped correctly
-                Entry &e = enclosingLoops.back();
+                Entry &e = enclosingControlStructures.back();
                 assert ( e == loopStmt );
 
@@ -97 +96 @@
                 // two labels, if they are used.
                 loopStmt->set_body( mutateLoop( loopStmt->get_body(), e ) );
-                enclosingLoops.pop_back();
+                enclosingControlStructures.pop_back();
 
                 return loopStmt;
@@ -111 +110 @@
         template< typename SwitchClass >
         Statement *MLEMutator::handleSwitchStmt( SwitchClass *switchStmt ) {
-                // generate a label for breaking out of a labeled switch 
+                // generate a label for breaking out of a labeled switch
                 Label brkLabel = generator->newLabel("switchBreak");
-                enclosingSwitches.push_back( Entry(switchStmt, brkLabel) );
-                mutateAll( switchStmt->get_branches(), *this ); 
-
-                Entry &e = enclosingSwitches.back();
+                enclosingControlStructures.push_back( Entry(switchStmt, brkLabel) );
+                mutateAll( switchStmt->get_branches(), *this );
+
+                Entry &e = enclosingControlStructures.back();
                 assert ( e == switchStmt );
 
                 // only generate break label if labeled break is used
                 if (e.isBreakUsed()) {
-                        // for the purposes of keeping switch statements uniform (i.e. all statements that are 
-                        // direct children of a switch should be CastStmts), append the exit label + break to the 
+                        // for the purposes of keeping switch statements uniform (i.e. all statements that are
+                        // direct children of a switch should be CastStmts), append the exit label + break to the
                         // last case statement; create a default case if there are no cases
                         std::list< Statement * > &branches = switchStmt->get_branches();
@@ -131 +130 @@
                         if ( CaseStmt * c = dynamic_cast< CaseStmt * >( branches.back() ) ) {
                                 std::list<Label> temp; temp.push_back( brkLabel );
-                                c->get_statements().push_back( new BranchStmt( temp, Label(""), BranchStmt::Break ) );
+                                c->get_statements().push_back( new BranchStmt( temp, Label("brkLabel"), BranchStmt::Break ) );
                         } else assert(0); // as of this point, all branches of a switch are still CaseStmts
                 }
 
-                assert ( enclosingSwitches.back() == switchStmt );
-                enclosingSwitches.pop_back();
+                assert ( enclosingControlStructures.back() == switchStmt );
+                enclosingControlStructures.pop_back();
                 return switchStmt;
         }
@@ -143 +142 @@
                 std::string originalTarget = branchStmt->get_originalTarget();
 
-                if ( branchStmt->get_type() == BranchStmt::Goto )
+                std::list< Entry >::reverse_iterator targetEntry;
+                if ( branchStmt->get_type() == BranchStmt::Goto ) {
                         return branchStmt;
-
-                // test if continue target is a loop
-                if ( branchStmt->get_type() == BranchStmt::Continue) {
-                        if ( enclosingLoops.empty() ) {
-                                throw SemanticError( "'continue' outside a loop" );
-                        } else if ( branchStmt->get_target() != "" && std::find( enclosingLoops.begin(), enclosingLoops.end(), (*targetTable)[branchStmt->get_target()] ) == enclosingLoops.end() ) {
-                                throw SemanticError( "'continue' target label must be an enclosing loop: " + originalTarget );
-                        }
-                }
-
-                if ( branchStmt->get_type() == BranchStmt::Break && (enclosingLoops.empty() && enclosingSwitches.empty() && enclosingBlocks.empty() ) )
-                        throw SemanticError( "'break' outside a loop or switch" );
-
-                if ( branchStmt->get_target() == "" ) return branchStmt;
-
-                if ( targetTable->find( branchStmt->get_target() ) == targetTable->end() )
+                } 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 ( targetEntry == enclosingControlStructures.rend() || ! isLoop( targetEntry->get_controlStructure() ) ) {
+                                throw SemanticError( "'continue' target must be an enclosing loop: " + originalTarget );
+                        }
+                } 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 ( 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)
-
-                std::list< Entry >::iterator check;
-                if ( ( check = std::find( enclosingLoops.begin(), enclosingLoops.end(), (*targetTable)[branchStmt->get_target()] ) ) == enclosingLoops.end() )
-                        // not in loop, checking if in block
-                        if ( (check = std::find( enclosingBlocks.begin(), enclosingBlocks.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingBlocks.end() )
-                                // neither in loop nor in block, checking if in switch/choose
-                                if ( (check = std::find( enclosingSwitches.begin(), enclosingSwitches.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingSwitches.end() )
-                                        throw SemanticError("The target specified in the exit loop statement does not correspond to an enclosing control structure: " + originalTarget );
-
+                }
+
+                // xxx - possibly remove this
                 // what about exiting innermost block or switch???
-                if ( enclosingLoops.back() == (*check) )
-                        return branchStmt;                              // exit the innermost loop (labels unnecessary)
+                // if ( enclosingControlStructures.back() == (*targetEntry) )
+                //      return branchStmt;                              // exit the innermost loop (labels unnecessary)
 
                 // branch error checks, get the appropriate label name and create a goto
@@ -179 +176 @@
                 switch ( branchStmt->get_type() ) {
                   case BranchStmt::Break:
-                                assert( check->useBreakExit() != "");
-                                exitLabel = check->useBreakExit();
+                                assert( targetEntry->useBreakExit() != "");
+                                exitLabel = targetEntry->useBreakExit();
                                 break;
                   case BranchStmt::Continue:
-                                assert( check->useContExit() != "");
-                                exitLabel = check->useContExit();
+                                assert( targetEntry->useContExit() != "");
+                                exitLabel = targetEntry->useContExit();
                                 break;
                   default:
@@ -190 +187 @@
                 } // switch
 
-                return new BranchStmt( std::list<Label>(), exitLabel, BranchStmt::Goto );
+                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 );
+                }
         }
 
@@ -206 +212 @@
                         // continue label goes in the body as the last statement
                         std::list< Label > labels; labels.push_back( e.useContExit() );
-                        newBody->get_kids().push_back( new NullStmt( labels ) );                        
+                        newBody->get_kids().push_back( new NullStmt( labels ) );
                 }
 
                 if ( e.isBreakUsed() ) {
-                        // break label goes after the loop -- it'll get set by the 
+                        // break label goes after the loop -- it'll get set by the
                         // outer mutator if we do this
-                        set_breakLabel( e.useBreakExit() );                     
+                        set_breakLabel( e.useBreakExit() );
                 }
 
@@ -231 +237 @@
 
         Statement *MLEMutator::mutate( ChooseStmt *switchStmt ) {
-                return handleSwitchStmt( switchStmt );          
+                return handleSwitchStmt( switchStmt );
         }