From b5056fa2d875ea3c52d258ead25d1bf5dbe4d883 Mon Sep 17 00:00:00 2001
From: Luke Gorrie <luke@snabb.co>
Date: Sun, 17 Dec 2017 14:50:25 +0000
Subject: [PATCH] lj_parse.c, lj_debug.c: Remove clever tricks in lineinfo
 encoding

Remove two clever tricks whose benefits don't justify their complexity:

The GCproto.lineinfo table used to exclude the first and last
bytecodes. The line numbers of those bytecodes had to be calculated as
a special case (using other state in the GCproto struct.) Now every
bytecode has an entry in the lineinfo table and is treated the same.

The GCproto.lineinfo table used to store delta values relative to the
first line. Now the absolute line number is stored. (The deltas helped
with a compression scheme that has previously been removed from RaptorJIT.)
---
 src/lj_debug.c |  5 +----
 src/lj_parse.c | 31 ++++---------------------------
 2 files changed, 5 insertions(+), 31 deletions(-)

diff --git a/src/lj_debug.c b/src/lj_debug.c
index ef08b7b2a3..939ec9c325 100644
--- a/src/lj_debug.c
+++ b/src/lj_debug.c
@@ -110,10 +110,7 @@ BCLine lj_debug_line(GCproto *pt, BCPos pc)
 {
   const void *lineinfo = proto_lineinfo(pt);
   if (pc <= pt->sizebc && lineinfo) {
-    BCLine first = pt->firstline;
-    if (pc == pt->sizebc) return first + pt->numline;
-    if (pc-- == 0) return first;
-    return first + ((BCLine *)lineinfo)[pc];
+    return mref(lineinfo, uint32_t)[pc];
   }
   return 0;
 }
diff --git a/src/lj_parse.c b/src/lj_parse.c
index 353dc9383d..1b50a640b5 100644
--- a/src/lj_parse.c
+++ b/src/lj_parse.c
@@ -1348,29 +1348,21 @@ static void fs_fixup_uv1(FuncState *fs, GCproto *pt, uint16_t *uv)
   memcpy(uv, fs->uvtmp, fs->nuv*sizeof(VarIndex));
 }
 
-#ifndef LUAJIT_DISABLE_DEBUGINFO
 /* Prepare lineinfo for prototype. */
 static size_t fs_prep_line(FuncState *fs, BCLine numline)
 {
-  return (fs->pc-1) * sizeof(BCLine);
+  return (fs->pc+1) * sizeof(BCLine);
 }
 
 /* Fixup lineinfo for prototype. */
 static void fs_fixup_line(FuncState *fs, GCproto *pt,
-			  void *lineinfo, BCLine numline)
+			  uint32_t *lineinfo, BCLine numline)
 {
-  BCInsLine *base = fs->bcbase + 1;
-  BCLine first = fs->linedefined;
-  MSize i = 0, n = fs->pc-1;
+  int i;
   pt->firstline = fs->linedefined;
   pt->numline = numline;
   setmref(pt->lineinfo, lineinfo);
-  uint32_t *li = (uint32_t *)lineinfo;
-  do {
-    BCLine delta = base[i].line - first;
-    lua_assert(delta >= 0);
-    li[i] = (uint32_t)delta;
-  } while (++i < n);
+  for (i = 0; i <= fs->pc; i++) lineinfo[i] = fs->bcbase[i].line;
 }
 
 /* Prepare variable info for prototype. */
@@ -1422,17 +1414,6 @@ static void fs_fixup_var(LexState *ls, GCproto *pt, uint8_t *p, size_t ofsvar)
   setmref(pt->varinfo, (char *)p + ofsvar);
   memcpy(p, sbufB(&ls->sb), sbuflen(&ls->sb));  /* Copy from temp. buffer. */
 }
-#else
-
-/* Initialize with empty debug info, if disabled. */
-#define fs_prep_line(fs, numline)		(UNUSED(numline), 0)
-#define fs_fixup_line(fs, pt, li, numline) \
-pt->firstline = pt->numline = 0, setmref((pt)->lineinfo, NULL)
-#define fs_prep_var(ls, fs, ofsvar)		(UNUSED(ofsvar), 0)
-#define fs_fixup_var(ls, pt, p, ofsvar) \
-  setmref((pt)->uvinfo, NULL), setmref((pt)->varinfo, NULL)
-
-#endif
 
 /* Check if bytecode op returns. */
 static int bcopisret(BCOp op)
@@ -2619,11 +2600,7 @@ GCproto *lj_parse(LexState *ls)
   FuncScope bl;
   GCproto *pt;
   lua_State *L = ls->L;
-#ifdef LUAJIT_DISABLE_DEBUGINFO
-  ls->chunkname = lj_str_newlit(L, "=");
-#else
   ls->chunkname = lj_str_newz(L, ls->chunkarg);
-#endif
   setstrV(L, L->top, ls->chunkname);  /* Anchor chunkname string. */
   incr_top(L);
   ls->level = 0;