From 559ee1e940c22a49ac8a39f6053917533e71243a Mon Sep 17 00:00:00 2001
From: grischka <grischka>
Date: Mon, 19 Dec 2016 00:27:08 +0100
Subject: [PATCH] i386-gen: fix USE_EBX

Restore ebx from *ebp because alloca might change esp.

Also disable USE_EBX for upcoming release.

Actually the benefit is less than one would expect, it
appears that tcc can't do much with more than 3 registers
except with extensive use of long longs where the disassembly
looks much prettier (and shorter also).

Also: tccgen/expr_cond() : fix wrong gv/save_regs order
---
 i386-gen.c | 15 ++++++++++-----
 tccgen.c   |  2 +-
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/i386-gen.c b/i386-gen.c
index 3a26f7a..946e42d 100644
--- a/i386-gen.c
+++ b/i386-gen.c
@@ -79,7 +79,7 @@ enum {
 #include "tcc.h"
 
 /* define to 1/0 to [not] have EBX as 4th register */
-#define USE_EBX 1
+#define USE_EBX 0
 
 ST_DATA const int reg_classes[NB_REGS] = {
     /* eax */ RC_INT | RC_EAX,
@@ -636,7 +636,15 @@ ST_FUNC void gfunc_epilog(void)
         o(0x585a); /* restore returned value, if any */
     }
 #endif
-    o(0x5b * USE_EBX); /* pop ebx */
+
+    /* align local size to word & save local variables */
+    v = (-loc + 3) & -4;
+
+#if USE_EBX
+    o(0x8b);
+    gen_modrm(TREG_EBX, VT_LOCAL, NULL, -(v+4));
+#endif
+
     o(0xc9); /* leave */
     if (func_ret_sub == 0) {
         o(0xc3); /* ret */
@@ -645,9 +653,6 @@ ST_FUNC void gfunc_epilog(void)
         g(func_ret_sub);
         g(func_ret_sub >> 8);
     }
-    /* align local size to word & save local variables */
-    
-    v = (-loc + 3) & -4; 
     saved_ind = ind;
     ind = func_sub_sp_offset - FUNC_PROLOG_SIZE;
 #ifdef TCC_TARGET_PE
diff --git a/tccgen.c b/tccgen.c
index dddeea1..8281d1e 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -5164,8 +5164,8 @@ static void expr_cond(void)
 #endif
             } else
                 rc = RC_INT;
-            save_regs(1);
             gv(rc);
+            save_regs(1);
             if (g)
                 gv_dup();
             tt = gvtst(1, 0);