If a conditional branch as an unconditional jump as target, that doesn't jump

[cc65] / src / cc65 / coptind.c

diff --git a/src/cc65/coptind.c b/src/cc65/coptind.c
index 81037b6fa04d6c2953c1bf075b1aceb07fe9b507..abb415e822cfb4efdd7d11f69be8a05d4cd49c17 100644 (file)
--- a/src/cc65/coptind.c
+++ b/src/cc65/coptind.c
@@ -430,14 +430,24 @@ unsigned OptJumpCascades (CodeSeg* S)
        /* Get this entry */
        CodeEntry* E = CS_GetEntry (S, I);
 
-               /* Check if it's a branch, if it has a jump label, if this jump
-        * label is not attached to the instruction itself, and if the
-        * target instruction is itself a branch.
+               /* Check:
+         *   - if it's a branch,
+         *   - if it has a jump label,
+         *   - if this jump label is not attached to the instruction itself,
+         *   - if the target instruction is itself a branch,
+         *   - if either the first branch is unconditional or the target of
+         *     the second branch is internal to the function.
+         * The latter condition will avoid conditional branches to targets
+         * outside of the function (usually incspx), which won't simplify the
+         * code, since conditional far branches are emulated by a short branch
+         * around a jump.
         */
-       if ((E->Info & OF_BRA) != 0        &&
-           (OldLabel = E->JumpTo) != 0    &&
-           (N = OldLabel->Owner) != E     &&
-           (N->Info & OF_BRA) != 0) {
+       if ((E->Info & OF_BRA) != 0             &&
+           (OldLabel = E->JumpTo) != 0         &&
+           (N = OldLabel->Owner) != E          &&
+           (N->Info & OF_BRA) != 0             &&
+            ((E->Info & OF_CBRA) == 0   ||
+             N->JumpTo != 0)) {        
 
            /* Check if we can use the final target label. This is the case,
             * if the target branch is an absolut branch, or if it is a