Changeset e39aa0f

Timestamp:

Jun 28, 2016, 3:33:01 PM (9 years ago)

Author:

Rob Schluntz <rschlunt@…>

Branches:

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

Children:

4dcea3f

Parents:

888cbe4

Message:

overhaul MLE code, attach label to break/continue statements so it can be used to generate dtor calls, mutate continue statements into goto statements so dtor generation works correctly

Location:

src

Files:

• ControlStruct/MLEMutator.cc (modified) (13 diffs)
• ControlStruct/MLEMutator.h (modified) (2 diffs)
• InitTweak/FixInit.cc (modified) (4 diffs)

src/ControlStruct/MLEMutator.cc

@@ -27 +27 @@
 #include "SynTree/Statement.h"
 #include "SynTree/Expression.h"
+#include "SynTree/Attribute.h"
 
 namespace ControlStruct {
@@ -32 +33 @@
                 delete targetTable;
                 targetTable = 0;
+        }
+        namespace {
+                Statement * isLoop( Statement * stmt ) { return dynamic_cast< WhileStmt * >( stmt ) ? stmt : dynamic_cast< ForStmt * >( stmt ) ? stmt : 0; }
         }
 
@@ -44 +48 @@
                         if ( ! get_breakLabel().empty() ) {
                                 std::list< Statement * >::iterator next = k+1;
-                                Statement * stmt = 0;
-                                if ( next == kids.end() ) {
-                                        std::list<Label> ls; ls.push_back( get_breakLabel() );
-                                        kids.push_back( stmt = new NullStmt( ls ) );
-                                } else {
-                                        (stmt = *next)->get_labels().push_back( get_breakLabel() );
-                                }
-                                stmt->get_labels().front().set_statement( stmt );
-
+                                std::list<Label> ls; ls.push_back( get_breakLabel() );
+                                kids.insert( next, new NullStmt( ls ) );
                                 set_breakLabel("");
                         } // if
@@ -62 +59 @@
                 if ( labeledBlock ) {
                         Label brkLabel = generator->newLabel("blockBreak");
-                        enclosingBlocks.push_back( Entry( cmpndStmt, brkLabel ) );
+                        enclosingControlStructures.push_back( Entry( cmpndStmt, brkLabel ) );
                 } // if
 
@@ -71 +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
 
@@ -89 +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 );
 
@@ -99 +96 @@
                 // two labels, if they are used.
                 loopStmt->set_body( mutateLoop( loopStmt->get_body(), e ) );
-                enclosingLoops.pop_back();
+                enclosingControlStructures.pop_back();
 
                 return loopStmt;
@@ -115 +112 @@
                 // generate a label for breaking out of a labeled switch
                 Label brkLabel = generator->newLabel("switchBreak");
-                enclosingSwitches.push_back( Entry(switchStmt, brkLabel) );
+                enclosingControlStructures.push_back( Entry(switchStmt, brkLabel) );
                 mutateAll( switchStmt->get_branches(), *this );
 
-                Entry &e = enclosingSwitches.back();
+                Entry &e = enclosingControlStructures.back();
                 assert ( e == switchStmt );
 
@@ -133 +130 @@
                         if ( CaseStmt * c = dynamic_cast< CaseStmt * >( branches.back() ) ) {
                                 std::list<Label> temp; temp.push_back( brkLabel );
-                                Statement * stmt = new BranchStmt( temp, Label(""), BranchStmt::Break );
-                                stmt->get_labels().front().set_statement( stmt );
-                                c->get_statements().push_back( stmt );
+                                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;
         }
@@ -147 +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
@@ -183 +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:
@@ -194 +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 );
+                }
         }
 
@@ -210 +212 @@
                         // continue label goes in the body as the last statement
                         std::list< Label > labels; labels.push_back( e.useContExit() );
-                        Statement * stmt = new NullStmt( labels );
-                        stmt->get_labels().front().set_statement( stmt );
-                        newBody->get_kids().push_back( stmt );
+                        newBody->get_kids().push_back( new NullStmt( labels ) );
                 }
 

src/ControlStruct/MLEMutator.h

@@ -56 +56 @@
                         bool operator!=( const Statement *stmt ) { return ( loop != stmt ); }
 
-                        bool operator==( const Entry &other ) { return ( loop == other.get_loop() ); }
+                        bool operator==( const Entry &other ) { return ( loop == other.get_controlStructure() ); }
 
-                        Statement *get_loop() const { return loop; }
+                        Statement *get_controlStructure() const { return loop; }
 
                         Label useContExit() { contUsed = true; return contExit; }
@@ -73 +73 @@
 
                 std::map< Label, Statement * > *targetTable;
-                std::list< Entry > enclosingBlocks, enclosingLoops, enclosingSwitches;
+                std::list< Entry > enclosingControlStructures;
                 Label breakLabel;
                 LabelGenerator *generator;

src/InitTweak/FixInit.cc

@@ -35 +35 @@
 bool ctorp = false;
 bool cpctorp = false;
-bool dtorp = true;
+bool dtorp = false;
 #define PRINT( text ) if ( ctordtorp ) { text }
 #define CP_CTOR_PRINT( text ) if ( ctordtorp || cpctorp ) { text }
@@ -499 +499 @@
                                 curVars.insert( objDecl );
                         }
-                        return Parent::visit( stmt );
+                        Parent::visit( stmt );
                 }
 
@@ -563 +563 @@
                 }
 
+                // Handle break/continue/goto in the same manner as C++.
+                // Basic idea: any objects that are in scope at the BranchStmt
+                // but not at the labelled (target) statement must be destructed.
+                // If there are any objects in scope at the target location but
+                // not at the BranchStmt then those objects would be uninitialized
+                // so notify the user of the error.
+                // See C++ Reference 6.6 Jump Statements for details.
                 void InsertDtors::handleGoto( BranchStmt * stmt ) {
-                        assert( stmt->get_type() == BranchStmt::Goto );
+                        assert( stmt->get_target() != "" && "BranchStmt missing a label" );
                         // S_L = lvars = set of objects in scope at label definition
                         // S_G = curVars = set of objects in scope at goto statement
@@ -602 +609 @@
 
                 void InsertDtors::visit( BranchStmt * stmt ) {
-                        // TODO: adding to the end of a block isn't sufficient, since
-                        // return/break/goto should trigger destructor when block is left.
                         switch( stmt->get_type() ) {
                                 case BranchStmt::Continue:
                                 case BranchStmt::Break:
-                                // xxx - easiest thing to do: generate a label for every break/continue
-                                // this label is unused, so attach unused attribute to it
-                                // finally, all of these cases can be the same (this is less efficient than it could be,
-                                // because the S_L-S_G check is unnecessary [the set should always be empty], but this
-                                // serves as a bit of a sanity check, so I'm okay with it.)
-                                        // xxx - this is insufficient, because multiple blocks can be opened in a switch or loop
-                                        insertDtors( reverseDeclOrder.front().begin(), reverseDeclOrder.front().end(), back_inserter( stmtsToAdd ) );
-                                        break;
+                                // could optimize the break/continue case, because the S_L-S_G check
+                                // is unnecessary (this set should always be empty), but it serves
+                                // as a small sanity check.
                                 case BranchStmt::Goto:
                                         handleGoto( stmt );