From 5813fd81d383f3e0520a41197ffa44b92b272cb9 Mon Sep 17 00:00:00 2001
From: mrdudz <mrdudz@users.noreply.github.com>
Date: Sun, 8 May 2022 13:20:18 +0200
Subject: [PATCH] add extra optimizer step that replaces BRA by JMP if the
 target is external

---
 src/cc65/coptjmp.c | 31 +++++++++++++++++++++++++++++++
 src/cc65/coptjmp.h |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/src/cc65/coptjmp.c b/src/cc65/coptjmp.c
index dd092a5ad..9dd4a29c5 100644
--- a/src/cc65/coptjmp.c
+++ b/src/cc65/coptjmp.c
@@ -194,6 +194,37 @@ unsigned OptBranchDist (CodeSeg* S)
 
 
 
+unsigned OptBranchDist2 (CodeSeg* S)
+/* Change BRA to JMP if target is an external symbol */
+{
+    unsigned Changes = 0;
+
+    /* Walk over the entries */
+    unsigned I = 0;
+    while (I < CS_GetEntryCount (S)) {
+
+        /* Get next entry */
+        CodeEntry* E = CS_GetEntry (S, I);
+
+       if ((CPUIsets[CPU] & (CPU_ISET_65SC02 |CPU_ISET_6502DTV)) != 0 && /* CPU has BRA */
+           (E->Info & OF_UBRA) != 0                                   && /* is a unconditional branch */
+           E->JumpTo == NULL) {                                          /* target is extern */
+            /* BRA jumps to external symbol and must be replaced by a JMP on the 65C02 CPU */
+            CE_ReplaceOPC (E, OP65_JMP);
+            ++Changes;
+        }
+
+        /* Next entry */
+        ++I;
+
+    }
+
+    /* Return the number of changes made */
+    return Changes;
+}
+
+
+
 /*****************************************************************************/
 /*                        Replace jumps to RTS by RTS                        */
 /*****************************************************************************/
diff --git a/src/cc65/coptjmp.h b/src/cc65/coptjmp.h
index 4cb7a2792..8df53415d 100644
--- a/src/cc65/coptjmp.h
+++ b/src/cc65/coptjmp.h
@@ -52,6 +52,9 @@
 unsigned OptBranchDist (CodeSeg* S);
 /* Change branches for the distance needed. */
 
+unsigned OptBranchDist2 (CodeSeg* S);
+/* If BRA points to an external symbol, change it to JMP */
+
 unsigned OptRTSJumps1 (CodeSeg* S);
 /* Replace jumps to RTS by RTS */