Added SBC optimizations suggested by Piotr Fusik

git-svn-id: svn://svn.cc65.org/cc65/trunk@1123 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/src/cc65/codegen.c b/src/cc65/codegen.c
index c3e06fd32705d60404f0ca5b8d906a407fded0e7..01bb115077a91cafb2eb7fbf49d80c4b76967f61 100644 (file)
--- a/src/cc65/codegen.c
+++ b/src/cc65/codegen.c
@@ -1748,11 +1748,10 @@ void g_subeqstatic (unsigned flags, unsigned long label, long offs,
                                AddCodeLine ("sbc #$%02X", (int)(val & 0xFF));
                                AddCodeLine ("sta %s", lbuf);
                            }
-                       } else {
+                       } else {              
+                   AddCodeLine ("eor #$FF");
                            AddCodeLine ("sec");
-                           AddCodeLine ("sta tmp1");
-                           AddCodeLine ("lda %s", lbuf);
-                           AddCodeLine ("sbc tmp1");
+                           AddCodeLine ("adc %s", lbuf);
                            AddCodeLine ("sta %s", lbuf);
                        }
                        if ((flags & CF_UNSIGNED) == 0) {
@@ -1784,14 +1783,13 @@ void g_subeqstatic (unsigned flags, unsigned long label, long offs,
                    AddCodeLine ("tax");
                    AddCodeLine ("lda %s", lbuf);
                }
-           } else {
-               AddCodeLine ("sta tmp1");
-               AddCodeLine ("lda %s", lbuf);
-               AddCodeLine ("sbc tmp1");
+           } else {          
+               AddCodeLine ("eor #$FF");
+                       AddCodeLine ("adc %s", lbuf);
                AddCodeLine ("sta %s", lbuf);
-                       AddCodeLine ("stx tmp1");
-               AddCodeLine ("lda %s+1", lbuf);
-               AddCodeLine ("sbc tmp1");
+               AddCodeLine ("txa");
+               AddCodeLine ("eor #$FF");
+                       AddCodeLine ("adc %s+1", lbuf);
                AddCodeLine ("sta %s+1", lbuf);
                AddCodeLine ("tax");
                AddCodeLine ("lda %s", lbuf);
@@ -1845,18 +1843,17 @@ void g_subeqlocal (unsigned flags, int offs, unsigned long val)
                    AddCodeLine ("lda (sp),y");
                    AddCodeLine ("sbc #$%02X", (unsigned char)val);
                } else {
-                   AddCodeLine ("sta tmp1");
-                   AddCodeLine ("lda (sp),y");
-                   AddCodeLine ("sbc tmp1");
+                   AddCodeLine ("eor #$FF");
+                   AddCodeLine ("adc (sp),y");
                }
                        AddCodeLine ("sta (sp),y");
                if ((flags & CF_UNSIGNED) == 0) {
-                   unsigned L = GetLocalLabel();
+                   unsigned L = GetLocalLabel();
                    AddCodeLine ("bpl %s", LocalLabelName (L));
-                   AddCodeLine ("dex");
-                   g_defcodelabel (L);
-               }
-                       break;
+                   AddCodeLine ("dex");
+                   g_defcodelabel (L);
+               }
+                       break;
                    }
                    /* FALLTHROUGH */