From 2b2c082efb11920ec7e720402079c2d2dae345b8 Mon Sep 17 00:00:00 2001
From: Colin Leroy-Mira <colin@colino.net>
Date: Sun, 20 Jul 2025 14:36:30 +0200
Subject: [PATCH] Fix bug in PR #2778

Don't replace incaxy like incax[1-8].
---
 src/cc65/codeopt.c  |  2 ++
 src/cc65/coptmisc.c | 64 +++++++++++++++++++++++++++++++++++++++++++--
 src/cc65/coptmisc.h |  5 +++-
 test/val/bug2205.c  |  9 +++++--
 4 files changed, 75 insertions(+), 5 deletions(-)

diff --git a/src/cc65/codeopt.c b/src/cc65/codeopt.c
index eccceccb3..3b88f1c16 100644
--- a/src/cc65/codeopt.c
+++ b/src/cc65/codeopt.c
@@ -114,6 +114,7 @@ static OptFunc DOptAdd4         = { OptAdd4,         "OptAdd4",          90, 0,
 static OptFunc DOptAdd5         = { OptAdd5,         "OptAdd5",         100, 0, 0, 0, 0, 0 };
 static OptFunc DOptAdd6         = { OptAdd6,         "OptAdd6",          40, 0, 0, 0, 0, 0 };
 static OptFunc DOptAXLoad       = { OptAXLoad,       "OptAXLoad",        50, 0, 0, 0, 0, 0 };
+static OptFunc DOptAXLoad2      = { OptAXLoad2,      "OptAXLoad2",       66, 0, 0, 0, 0, 0 };
 static OptFunc DOptAXOps        = { OptAXOps,        "OptAXOps",         50, 0, 0, 0, 0, 0 };
 static OptFunc DOptBNegA1       = { OptBNegA1,       "OptBNegA1",       100, 0, 0, 0, 0, 0 };
 static OptFunc DOptBNegA2       = { OptBNegA2,       "OptBNegA2",       100, 0, 0, 0, 0, 0 };
@@ -876,6 +877,7 @@ static unsigned RunOptGroup7 (CodeSeg* S)
         */
         Changes += RunOptFunc (S, &DOptUnusedLoads, 1);
         Changes += RunOptFunc (S, &DOptAXLoad, 5);
+        Changes += RunOptFunc (S, &DOptAXLoad2, 5);
         Changes += RunOptFunc (S, &DOptUnusedStores, 1);
         Changes += RunOptFunc (S, &DOptJumpTarget1, 5);
         Changes += RunOptFunc (S, &DOptStore5, 1);
diff --git a/src/cc65/coptmisc.c b/src/cc65/coptmisc.c
index 0ba447562..3e1b40b8d 100644
--- a/src/cc65/coptmisc.c
+++ b/src/cc65/coptmisc.c
@@ -499,7 +499,7 @@ unsigned OptAXOps (CodeSeg* S)
 
 
 unsigned OptAXLoad (CodeSeg* S)
-/* Merge jsr incax/jsr ldaxi into ldy/jsr ldaxidx */
+/* Merge jsr incax[1-8]/jsr ldaxi into ldy/jsr ldaxidx */
 {
     unsigned Changes = 0;
     unsigned I;
@@ -514,9 +514,10 @@ unsigned OptAXLoad (CodeSeg* S)
         /* Get the next entry */
         const CodeEntry* E = CS_GetEntry (S, I);
 
-        /* Check for incax followed by jsr/jmp ldaxi */
+        /* Check for incax[1-8] followed by jsr/jmp ldaxi */
         if (E->OPC == OP65_JSR                            &&
             strncmp (E->Arg, "incax", 5) == 0             &&
+            strcmp (E->Arg, "incaxy") != 0                &&
             (N = CS_GetNextEntry (S, I)) != 0             &&
             (N->OPC == OP65_JSR || N->OPC == OP65_JMP)    &&
             strcmp (N->Arg, "ldaxi") == 0                 &&
@@ -555,6 +556,65 @@ unsigned OptAXLoad (CodeSeg* S)
 
 
 
+unsigned OptAXLoad2 (CodeSeg* S)
+/* Merge ldy/jsr incaxy/jsr ldaxi into ldy/jsr ldaxidx */
+{
+    unsigned Changes = 0;
+    unsigned I;
+
+    /* Walk over the entries */
+    I = 0;
+    while (I < CS_GetEntryCount (S)) {
+
+        signed Val;
+        CodeEntry* E[3];
+        CodeEntry *X;
+        char *End;
+
+        /* Get the next entry */
+        E[0] = CS_GetEntry (S, I);
+
+        /* Check for ldy followed by incaxy followed by jsr/jmp ldaxi */
+        if (E[0]->OPC == OP65_LDY                            &&
+            E[0]->AM == AM65_IMM                             &&
+            CS_GetEntries (S, E+1, I+1, 2)                   &&
+            E[1]->OPC == OP65_JSR                            &&
+            strcmp (E[1]->Arg, "incaxy") == 0                &&
+            (E[2]->OPC == OP65_JSR || E[2]->OPC == OP65_JMP) &&
+            strcmp (E[2]->Arg, "ldaxi") == 0                 &&
+            !CS_RangeHasLabel (S, I, 3)) {
+
+            /* Replace with ldy (y+1) / jsr ldaxidx */
+            Val = strtoul(E[0]->Arg + 1, &End, 16);
+            Val++;
+
+            X = NewCodeEntry (OP65_LDY, AM65_IMM, MakeHexArg(Val), 0, E[0]->LI);
+            CS_InsertEntry (S, X, I+3);
+            X = NewCodeEntry (E[2]->OPC, AM65_ABS, "ldaxidx", 0, E[0]->LI);
+            CS_InsertEntry (S, X, I+4);
+
+            CS_DelEntries (S, I, 3);
+
+            /* Regenerate register info */
+            CS_GenRegInfo (S);
+
+            /* Remember we had changes */
+            ++Changes;
+
+        } else {
+
+            /* Next entry */
+            ++I;
+        }
+
+    }
+
+    /* Return the number of changes made */
+    return Changes;
+}
+
+
+
 unsigned OptGotoSPAdj (CodeSeg* S)
 /* Optimize SP adjustment for forward 'goto' */
 {
diff --git a/src/cc65/coptmisc.h b/src/cc65/coptmisc.h
index cc6d1c519..df76e84f4 100644
--- a/src/cc65/coptmisc.h
+++ b/src/cc65/coptmisc.h
@@ -102,7 +102,10 @@ unsigned OptAXOps (CodeSeg* S);
 */
 
 unsigned OptAXLoad (CodeSeg* S);
-/* Merge adjacent calls to incax/ldaxi into ldy/ldaxidx */
+/* Merge jsr incax[1-8]/jsr ldaxi into ldy/jsr ldaxidx */
+
+unsigned OptAXLoad2 (CodeSeg* S);
+/* Merge ldy/jsr incaxy/jsr ldaxi into ldy/jsr ldaxidx */
 
 unsigned OptGotoSPAdj (CodeSeg* S);
 /* Optimize SP adjustment for forward 'goto' */
diff --git a/test/val/bug2205.c b/test/val/bug2205.c
index 1b5458249..0ca78e9b1 100644
--- a/test/val/bug2205.c
+++ b/test/val/bug2205.c
@@ -3,18 +3,23 @@
 struct Object
 {
     int a;
-    int data[10];
+    int data[20];
 };
 
 struct Object object_data = { 0x0102, {0x0304, 0x0506, 
                              0x0708, 0x090A, 0x0B0C,
                              0x0D0E, 0x0F10, 0x1112,
-                             0x1314, 0x1516}};
+                             0x1314, 0x1516, 0x1718,
+                             0x1920, 0x2122, 0x2324,
+                             0x2526, 0x2728, 0x2930,
+                             0x3132, 0x3334, 0x3536}};
 
 TEST
 {
     struct Object *o = &object_data;
     ASSERT_IsTrue(o->a == 0x0102, "Wrong value for a");
     ASSERT_IsTrue(o->data[2] == 0x0708, "Wrong value for data[2]");
+    ASSERT_IsTrue(o->data[8] == 0x1314, "Wrong value for data[8]");
+    ASSERT_IsTrue(o->data[19] == 0x3536, "Wrong value for data[19]");
 }
 ENDTEST