store the symbol hash to make global lookups slightly faster

devyn · Aug 15, 2023 · 4fa4cd7 · 4fa4cd7
1 parent c4e2e84
commit 4fa4cd7
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Showing 4 changed files with 8 additions and 4 deletions.
diff --git a/stage1/object.h b/stage1/object.h
@@ -13,6 +13,7 @@ struct lisp_cons {
 struct lisp_symbol {
   char *buf;
   unsigned long len; // cap = len for symbols (they must be allocated with exact size)
+  char hash; // for hashtables
 };
 
 struct lisp_string {

diff --git a/stage1/object.h.s b/stage1/object.h.s
@@ -6,6 +6,7 @@
 
 .set LISP_SYMBOL_BUF, 8
 .set LISP_SYMBOL_LEN, 16
+.set LISP_SYMBOL_HASH, 24
 
 .set LISP_CONS_HEAD, 8
 .set LISP_CONS_TAIL, 16

diff --git a/stage1/symbol.s b/stage1/symbol.s
@@ -107,8 +107,12 @@ symbol_intern:
         mv a1, s1
         mv a2, s4
         call mem_copy
+        # get symbol hash
+        mv a0, s4
+        mv a1, s2
+        call symbol_hash
         # create a new object for the symbol
-        mv a3, zero
+        andi a3, a0, 0xff # LISP_SYMBOL_HASH
         mv a2, s2 # LISP_SYMBOL_LEN
         mv a1, s4 # LISP_SYMBOL_BUF
         li a0, LISP_OBJECT_TYPE_SYMBOL

diff --git a/stage1/words.s b/stage1/words.s
@@ -463,9 +463,7 @@ get_words_ptr:
         lwu t2, LISP_OBJECT_TYPE(t1)
         li t3, LISP_OBJECT_TYPE_SYMBOL
         bne t2, t3, .Lget_words_ptr_error # not symbol => error
-        ld a0, LISP_SYMBOL_BUF(t1)
-        ld a1, LISP_SYMBOL_LEN(t1)
-        call symbol_hash
+        lb a0, LISP_SYMBOL_HASH(t1)
         # mask the hash to number of bits
         andi a0, a0, (1 << WORDS_HASH_BITS) - 1
         # times 8 (double word)