From d615e78e08201906e2f1dfc054b080fbbf7db428 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 6 Apr 2000 14:36:52 -0300
Subject: new optimization: jumps to jumps
---
lcode.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
(limited to 'lcode.c')
diff --git a/lcode.c b/lcode.c
index de4c3623..750def9a 100644
--- a/lcode.c
+++ b/lcode.c
@@ -1,5 +1,5 @@
/*
-** $Id: lcode.c,v 1.19 2000/04/04 20:48:44 roberto Exp roberto $
+** $Id: lcode.c,v 1.20 2000/04/05 17:51:58 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
@@ -171,7 +171,12 @@ static void luaK_neq (FuncState *fs) {
int luaK_jump (FuncState *fs) {
- return luaK_S(fs, OP_JMP, NO_JUMP, 0);
+ int j = luaK_S(fs, OP_JMP, NO_JUMP, 0);
+ if (j == fs->lasttarget) { /* possible jumps to this jump? */
+ luaK_concat(fs, &j, fs->jlt); /* keep them on hold */
+ fs->jlt = NO_JUMP;
+ }
+ return j;
}
@@ -220,11 +225,17 @@ static int luaK_getjump (FuncState *fs, int pc) {
/*
+** discharge list of jumps to last target.
** returns current `pc' and marks it as a jump target (to avoid wrong
** optimizations with consecutive instructions not in the same basic block).
*/
int luaK_getlabel (FuncState *fs) {
- fs->lasttarget = fs->pc;
+ if (fs->pc != fs->lasttarget) {
+ int lasttarget = fs->lasttarget;
+ fs->lasttarget = fs->pc;
+ luaK_patchlist(fs, fs->jlt, lasttarget); /* discharge old list `jlt' */
+ fs->jlt = NO_JUMP; /* nobody jumps to this new label (till now) */
+ }
return fs->pc;
}
@@ -394,7 +405,10 @@ static void luaK_patchlistaux (FuncState *fs, int list, int target,
void luaK_patchlist (FuncState *fs, int list, int target) {
- luaK_patchlistaux(fs, list, target, OP_END, 0);
+ if (target == fs->lasttarget) /* same target that list `jlt'? */
+ luaK_concat(fs, &fs->jlt, list); /* delay fixing */
+ else
+ luaK_patchlistaux(fs, list, target, OP_END, 0);
}
--
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