Changeset 2efe4b8

Timestamp:

Apr 25, 2018, 3:42:34 PM (5 years ago)

Author:

Aaron Moss <a3moss@…>

Branches:

new-env, with_gc

Children:

1cdfa82

Parents:

5af7306

Message:

Assorted GC bugfixes

Location:

src

Files:

• Common/GC.cc (modified) (1 diff)
• Common/GC.h (modified) (4 diffs)
• GenPoly/Box.cc (modified) (2 diffs)
• ResolvExpr/Resolver.cc (modified) (4 diffs)
• SynTree/GcTracer.h (modified) (4 diffs)

src/Common/GC.cc

@@ -77 +77 @@
 }
 
-void GC::new_generation() {
+GC_Guard GC::new_generation() {
         if ( ++g == gens.size() ) { gens.emplace_back(); }  // ensure new generation available
         mark = !mark;  // switch mark so aged young objects will still be unmarked in old
+        return { *this, g };
 }
 

src/Common/GC.h

@@ -16 +16 @@
 #pragma once
 
+#include <cassert>
 #include <vector>
 
 class GC_Object;
 class BaseSyntaxNode;
+class GC_Guard;
 
 /// Manually traced and called garbage collector
 class GC {
         friend class GcTracer;
+        friend class GC_Guard;
+
+        /// Collects the youngest generation, placing survivors in previous generation.
+        /// Young generation objects cannot be kept alive by pointers from older generation.
+        /// Older generation is used for subsequent new objects.
+        void collect_young();
 public:
         /// Gets singleton GC instance
@@ -38 +46 @@
 
         /// Start new generation for subsequent new objects
-        void new_generation();
+        GC_Guard new_generation();
 
         /// Traces all static roots
         void trace_static_roots();
-
-        /// Collects the youngest generation, placing survivors in previous generation.
-        /// Young generation objects cannot be kept alive by pointers from older generation.
-        /// Older generation is used for subsequent new objects.
-        void collect_young();
 
         /// Collects oldest generation; use oldest generation afterward.
@@ -68 +71 @@
 };
 
+/// Cleanup object for young generation
+class GC_Guard {
+        friend class GC;
+
+        GC& gc;      ///< GC associated with
+        unsigned g;  ///< Generation constructed for
+
+        GC_Guard( GC& gc, unsigned g ) : gc(gc), g(g) {}
+
+public:
+        ~GC_Guard() {
+                assert( gc.g == g && "collecting current generation" );
+                gc.collect_young();
+        }
+};
+
 /// Use young generation until next collection
-inline void new_generation() { GC::get().new_generation(); }
+inline GC_Guard new_generation() { return GC::get().new_generation(); }
 
 // /// no-op default trace
@@ -84 +103 @@
 }
 
-/// Traces young-generation roots and does a young collection
+/// Traces roots without collecting
 template<typename... Args>
-inline void collect_young(Args&... roots) {
+inline void trace(Args&... roots) {
         GC& gc = GC::get();
         traceAll(gc, roots...);
         gc.trace_static_roots();
-        gc.collect_young();
 }
 
-/// Traces roots and collects other elements
+/// Traces roots and collects other elements; should not be any young generations live
 template<typename... Args>
 inline void collect(Args&... roots) {

src/GenPoly/Box.cc

@@ -283 +283 @@
                 for ( std::list< TypeDecl* >::const_iterator param = otypeParams.begin(); 
                                 param != otypeParams.end(); ++param ) {
-                        TypeInstType paramType( Type::Qualifiers(), (*param)->get_name(), *param );
-                        std::string paramName = mangleType( &paramType );
+                        auto paramType = new TypeInstType( Type::Qualifiers(), (*param)->get_name(), *param );
+                        std::string paramName = mangleType( paramType );
                         layoutFnType->get_parameters().push_back( new ObjectDecl( sizeofName( paramName ), Type::StorageClasses(), LinkageSpec::Cforall, 0, sizeAlignType->clone(), 0 ) );
                         layoutFnType->get_parameters().push_back( new ObjectDecl( alignofName( paramName ), Type::StorageClasses(), LinkageSpec::Cforall, 0, sizeAlignType->clone(), 0 ) );
@@ -1436 +1436 @@
                         if ( Type * base = typeDecl->base ) {
                                 // add size/align variables for opaque type declarations
-                                TypeInstType inst( Type::Qualifiers(), typeDecl->name, typeDecl );
-                                std::string typeName = mangleType( &inst );
+                                auto inst = new TypeInstType( Type::Qualifiers(), typeDecl->name, typeDecl );
+                                std::string typeName = mangleType( inst );
                                 Type *layoutType = new BasicType( Type::Qualifiers(), BasicType::LongUnsignedInt );
 

src/ResolvExpr/Resolver.cc

@@ -148 +148 @@
                         assertf( untyped, "expected a non-null expression." );
 
-                        new_generation();  // set up GC young generation for this top-level expression
+                        auto guard = new_generation();  // set up GC generation for this top-level expression
 
                         TypeEnvironment env;
@@ -177 +177 @@
                         findMinCost( candidates.begin(), candidates.end(), back_inserter( winners ) );
                         if ( winners.size() == 0 ) {
-                                collect_young();
                                 SemanticError( untyped, toString( 
                                         "No reasonable alternatives for ", kindStr, (kindStr != "" ? " " : ""), 
@@ -189 +188 @@
                                 printAlts( winners, stream, 1 );
                                 
-                                collect_young();
                                 SemanticError( untyped->location, stream.str() );
                         }
@@ -196 +194 @@
                         Alternative & choice = winners.front();
                         if ( findDeletedExpr( choice.expr ) ) {
-                                collect_young( choice.expr );
+                                trace( choice.expr );
                                 SemanticError( choice.expr, 
                                         "Unique best alternative includes deleted identifier in " );
                         }
                         alt = std::move( choice );
-                        collect_young( alt );
+                        trace( alt );
                 }
 

src/SynTree/GcTracer.h

@@ -20 +20 @@
 #include "BaseSyntaxNode.h"
 #include "Expression.h"
+#include "Label.h"
 #include "Type.h"
 
@@ -53 +54 @@
         }
 
+        void postvisit( AggregateDecl* decl ) {
+                acceptAll( decl->attributes, *visitor );
+        }
+
         void postvisit( DeclarationWithType* decl ) {
                 maybeAccept( decl->asmName, *visitor );
@@ -73 +78 @@
         }
 
+        void postvisit( UniqueExpr* expr ) {
+                postvisit( static_cast<Expression*>(expr) );
+                maybeAccept( expr->object, *visitor );
+                maybeAccept( expr->var, *visitor );
+        }
+
         void postvisit( UntypedExpr* expr ) {
                 postvisit( static_cast<Expression*>(expr) );
@@ -81 +92 @@
                 postvisit( static_cast<Expression*>(expr) );
                 maybeAccept( expr->var, *visitor );  // not in PassVisitor because it causes cycle
+        }
+
+private:
+        void visit( Label& lbl ) {
+                acceptAll( lbl.get_attributes(), *visitor );
+                maybeAccept( lbl.get_statement(), *visitor );  // xxx - not sure this is needed...
+        }
+
+public:
+        void postvisit( Statement* stmt ) {
+                for ( Label& l : stmt->labels ) {
+                        visit( l );
+                }
         }