Merge pull request #2742 from kugelfuhr/kugelfuhr/sp-backwards-compat

Allow "sp" as an alias for "c_sp" to avoid breaking old code

.github/checks/Makefile

@@ -40,4 +40,7 @@ sorted: sorted.sh sorted_codeopt.sh sorted_opcodes.sh
 	@./sorted_codeopt.sh
 	@./sorted_opcodes.sh
 
+checksp: checksp.sh
+	@./checksp.sh
+
 endif

.github/checks/checksp.sh

@@ -0,0 +1,22 @@
+#! /bin/bash
+OD65_EXE=../bin/od65
+CHECK_PATH=../../libwrk
+
+cd "${CHECK_PATH}" || {
+    echo "error: Directory ${CHECK_PATH} doesn't seem to exist" >&2
+    exit 1
+}
+
+[ -x "${OD65_EXE}" ] || {
+    echo "error: This check requires the od65 executable to be built" >&2
+    exit 1
+}
+
+EXITCODE=0
+find . -name \*.o -print | while read OBJ; do
+    "${OD65_EXE}" --dump-imports "${OBJ}" | grep -q "\"sp\"" && {
+        echo "error: Usage of symbol 'sp' found in module ${OBJ}" >&2
+        EXITCODE=1
+    }
+done
+exit ${EXITCODE}

.github/workflows/build-on-pull-request.yml

@@ -39,6 +39,9 @@ jobs:
       - name: Build the platform libraries.
         shell: bash
         run: make -j2 lib QUIET=1
+      - name: check test that no modules use sp
+        shell: bash
+        run: make -j2 checksp QUIET=1             
       - name: Run the regression tests.
         shell: bash
         run: make -j2 test QUIET=1

Makefile

@@ -53,6 +53,10 @@ checkstyle:
 sorted:
 	@$(MAKE) -C .github/checks --no-print-directory $@
 
+# check that no modules use "sp", requires the binaries to be built first
+checksp:
+	@$(MAKE) -C .github/checks --no-print-directory $@
+
 # runs regression tests, requires libtest target libraries
 test:
 	@$(MAKE) -C test                 --no-print-directory $@

asminc/zeropage.inc

@@ -13,6 +13,12 @@
         .globalzp       tmp1, tmp2, tmp3, tmp4
         .globalzp       regbank
 
+        ; The following symbol is supplied for compatibility reasons only, it
+        ; will get removed in future versions. Using it will cause a linker
+        ; warning.
+        .globalzp       sp
+
+
 ; The size of the register bank
 regbanksize     = 6
 

libsrc/runtime/sp-compat.s

@@ -0,0 +1,11 @@
+;
+; Kugelfuhr, 2025-06-26
+;
+; Add "sp" as an alias for "c_sp" so we don't break old code but emit a
+; linker warning if it is used. Added after renaming "sp" to "c_sp".
+;
+
+.include        "zeropage.inc"
+.export         sp := c_sp
+.assert         0, ldwarning, "Symbol 'sp' is deprecated - please use 'c_sp' instead"
+

test/asm/listing/080-sp-compat.s

@@ -0,0 +1,7 @@
+.include "zeropage.inc"
+
+.proc   _func
+        ldy     #0
+        lda     (sp),y
+        rts
+.endproc

test/asm/listing/ref/080-sp-compat.ld65err2-ref

@@ -0,0 +1 @@
+ld65: Warning: runtime/sp-compat.s:10: Symbol 'sp' is deprecated - please use 'c_sp' instead