memoization for resolve

2 files changed, 93 insertions, 40 deletions

diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index 321ac9428ea..e0d58c14a9a 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -915,30 +915,63 @@ fn idx_push<T>(vec: &mut ~[T], val: T) -> uint {
 
 /// Resolve a syntax object to a name, per MTWT.
 pub fn mtwt_resolve(id : Ident) -> Name {
-    resolve_internal(id, get_sctable())
+    resolve_internal(id, get_sctable(), get_resolve_table())
+}
+
+// FIXME #4536: must be pub for testing
+pub type ResolveTable = HashMap<(Name,SyntaxContext),Name>;
+
+// okay, I admit, putting this in TLS is not so nice:
+// fetch the SCTable from TLS, create one if it doesn't yet exist.
+pub fn get_resolve_table() -> @mut ResolveTable {
+    static resolve_table_key: local_data::Key<@@mut ResolveTable> = &local_data::Key;
+    match local_data::get(resolve_table_key, |k| k.map(|&k| *k)) {
+        None => {
+            let new_table = @@mut HashMap::new();
+            local_data::set(resolve_table_key,new_table);
+            *new_table
+        },
+        Some(intr) => *intr
+    }
 }
 
 // Resolve a syntax object to a name, per MTWT.
+// adding memoization to possibly resolve 500+ seconds in resolve for librustc (!)
 // FIXME #4536 : currently pub to allow testing
-pub fn resolve_internal(id : Ident, table : &mut SCTable) -> Name {
-    match table.table[id.ctxt] {
-        EmptyCtxt => id.name,
-        // ignore marks here:
-        Mark(_,subctxt) => resolve_internal(Ident{name:id.name, ctxt: subctxt},table),
-        // do the rename if necessary:
-        Rename(Ident{name,ctxt},toname,subctxt) => {
-            // this could be cached or computed eagerly:
-            let resolvedfrom = resolve_internal(Ident{name:name,ctxt:ctxt},table);
-            let resolvedthis = resolve_internal(Ident{name:id.name,ctxt:subctxt},table);
-            if ((resolvedthis == resolvedfrom)
-                && (marksof(ctxt,resolvedthis,table)
-                    == marksof(subctxt,resolvedthis,table))) {
-                toname
-            } else {
-                resolvedthis
-            }
+pub fn resolve_internal(id : Ident,
+                        table : &mut SCTable,
+                        resolve_table : &mut ResolveTable) -> Name {
+    let key = (id.name,id.ctxt);
+    match resolve_table.contains_key(&key) {
+        false => {
+            let resolved = {
+                match table.table[id.ctxt] {
+                    EmptyCtxt => id.name,
+                    // ignore marks here:
+                    Mark(_,subctxt) => resolve_internal(Ident{name:id.name, ctxt: subctxt},table,resolve_table),
+                    // do the rename if necessary:
+                    Rename(Ident{name,ctxt},toname,subctxt) => {
+                        let resolvedfrom = resolve_internal(Ident{name:name,ctxt:ctxt},table,resolve_table);
+                        let resolvedthis = resolve_internal(Ident{name:id.name,ctxt:subctxt},table,resolve_table);
+                        if ((resolvedthis == resolvedfrom)
+                            && (marksof(ctxt,resolvedthis,table)
+                                == marksof(subctxt,resolvedthis,table))) {
+                            toname
+                        } else {
+                            resolvedthis
+                        }
+                    }
+                    IllegalCtxt() => fail!(~"expected resolvable context, got IllegalCtxt")
+                }
+            };
+            resolve_table.insert(key,resolved);
+            resolved
+        }
+        true => {
+            // it's guaranteed to be there, because we just checked that it was
+            // there and we never remove anything from the table:
+            *(resolve_table.find(&key).unwrap())
         }
-        IllegalCtxt() => fail!(~"expected resolvable context, got IllegalCtxt")
     }
 }
 
@@ -1017,20 +1050,21 @@ mod test {
     use super::*;
     use std::io;
     use opt_vec;
+    use std::hash::HashMap;
 
-    fn ident_to_segment(id : &ident) -> PathSegment {
+    fn ident_to_segment(id : &Ident) -> PathSegment {
         PathSegment{identifier:id.clone(), lifetime: None, types: opt_vec::Empty}
     }
 
     #[test] fn idents_name_eq_test() {
-        assert!(segments_name_eq([ident{name:3,ctxt:4},
-                                   ident{name:78,ctxt:82}].map(ident_to_segment),
-                                 [ident{name:3,ctxt:104},
-                                   ident{name:78,ctxt:182}].map(ident_to_segment)));
-        assert!(!segments_name_eq([ident{name:3,ctxt:4},
-                                    ident{name:78,ctxt:82}].map(ident_to_segment),
-                                  [ident{name:3,ctxt:104},
-                                    ident{name:77,ctxt:182}].map(ident_to_segment)));
+        assert!(segments_name_eq([Ident{name:3,ctxt:4},
+                                   Ident{name:78,ctxt:82}].map(ident_to_segment),
+                                 [Ident{name:3,ctxt:104},
+                                   Ident{name:78,ctxt:182}].map(ident_to_segment)));
+        assert!(!segments_name_eq([Ident{name:3,ctxt:4},
+                                    Ident{name:78,ctxt:82}].map(ident_to_segment),
+                                  [Ident{name:3,ctxt:104},
+                                    Ident{name:77,ctxt:182}].map(ident_to_segment)));
     }
 
     #[test] fn xorpush_test () {
@@ -1162,29 +1196,30 @@ mod test {
     #[test] fn resolve_tests () {
         let a = 40;
         let mut t = new_sctable_internal();
+        let mut rt = HashMap::new();
         // - ctxt is MT
-        assert_eq!(resolve_internal(id(a,EMPTY_CTXT),&mut t),a);
+        assert_eq!(resolve_internal(id(a,EMPTY_CTXT),&mut t, &mut rt),a);
         // - simple ignored marks
         { let sc = unfold_marks(~[1,2,3],EMPTY_CTXT,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t),a);}
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),a);}
         // - orthogonal rename where names don't match
         { let sc = unfold_test_sc(~[R(id(50,EMPTY_CTXT),51),M(12)],EMPTY_CTXT,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t),a);}
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),a);}
         // - rename where names do match, but marks don't
         { let sc1 = new_mark_internal(1,EMPTY_CTXT,&mut t);
          let sc = unfold_test_sc(~[R(id(a,sc1),50),
                                    M(1),
                                    M(2)],
                                  EMPTY_CTXT,&mut t);
-        assert_eq!(resolve_internal(id(a,sc),&mut t), a);}
+        assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), a);}
         // - rename where names and marks match
         { let sc1 = unfold_test_sc(~[M(1),M(2)],EMPTY_CTXT,&mut t);
          let sc = unfold_test_sc(~[R(id(a,sc1),50),M(1),M(2)],EMPTY_CTXT,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t), 50); }
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 50); }
         // - rename where names and marks match by literal sharing
         { let sc1 = unfold_test_sc(~[M(1),M(2)],EMPTY_CTXT,&mut t);
          let sc = unfold_test_sc(~[R(id(a,sc1),50)],sc1,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t), 50); }
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 50); }
         // - two renames of the same var.. can only happen if you use
         // local-expand to prevent the inner binding from being renamed
         // during the rename-pass caused by the first:
@@ -1192,22 +1227,28 @@ mod test {
         { let sc = unfold_test_sc(~[R(id(a,EMPTY_CTXT),50),
                                     R(id(a,EMPTY_CTXT),51)],
                                   EMPTY_CTXT,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t), 51); }
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 51); }
         // the simplest double-rename:
         { let a_to_a50 = new_rename_internal(id(a,EMPTY_CTXT),50,EMPTY_CTXT,&mut t);
          let a50_to_a51 = new_rename_internal(id(a,a_to_a50),51,a_to_a50,&mut t);
-         assert_eq!(resolve_internal(id(a,a50_to_a51),&mut t),51);
+         assert_eq!(resolve_internal(id(a,a50_to_a51),&mut t, &mut rt),51);
          // mark on the outside doesn't stop rename:
          let sc = new_mark_internal(9,a50_to_a51,&mut t);
-         assert_eq!(resolve_internal(id(a,sc),&mut t),51);
+         assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),51);
          // but mark on the inside does:
          let a50_to_a51_b = unfold_test_sc(~[R(id(a,a_to_a50),51),
                                               M(9)],
                                            a_to_a50,
                                            &mut t);
-         assert_eq!(resolve_internal(id(a,a50_to_a51_b),&mut t),50);}
+         assert_eq!(resolve_internal(id(a,a50_to_a51_b),&mut t, &mut rt),50);}
+    }
+
+    #[test] fn mtwt_resolve_test(){
+        let a = 40;
+        assert_eq!(mtwt_resolve(id(a,EMPTY_CTXT)),a);
     }
 
+
     #[test] fn hashing_tests () {
         let mut t = new_sctable_internal();
         assert_eq!(new_mark_internal(12,EMPTY_CTXT,&mut t),2);
@@ -1217,4 +1258,16 @@ mod test {
         // I'm assuming that the rename table will behave the same....
     }
 
+    #[test] fn resolve_table_hashing_tests() {
+        let mut t = new_sctable_internal();
+        let mut rt = HashMap::new();
+        assert_eq!(rt.len(),0);
+        resolve_internal(id(30,EMPTY_CTXT),&mut t, &mut rt);
+        assert_eq!(rt.len(),1);
+        resolve_internal(id(39,EMPTY_CTXT),&mut t, &mut rt);
+        assert_eq!(rt.len(),2);
+        resolve_internal(id(30,EMPTY_CTXT),&mut t, &mut rt);
+        assert_eq!(rt.len(),2);
+    }
+
 }
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 39e0f85920c..aa26feec28c 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -737,8 +737,8 @@ mod test {
     use ast;
     use ast_util;
 
-    fn mark_ident(id : ast::ident, m : ast::Mrk) -> ast::ident {
-        ast::ident{name:id.name,ctxt:ast_util::new_mark(m,id.ctxt)}
+    fn mark_ident(id : ast::Ident, m : ast::Mrk) -> ast::Ident {
+        ast::Ident{name:id.name,ctxt:ast_util::new_mark(m,id.ctxt)}
     }
 
     #[test] fn mtwt_token_eq_test() {