fix: do not emit CHKBREAK after label

src/api/optimize.py

@@ -106,6 +106,16 @@ def visit_FUNCTION(self, node: symbols.FUNCTION):
         yield (yield self.generic_visit(node))
 
     def visit_BLOCK(self, node):
+        # Remove CHKBREAK after labels
+
+        i = 0
+        while i < len(node) - 1:
+            child = node[i]
+            if child.token == "LABEL" and node[i + 1].token == "CHKBREAK":
+                node.pop(i + 1)
+                continue
+            i += 1
+
         warning_emitted = False
         i = 0
         while i < len(node):

tests/functional/zx48k/break.asm

@@ -23,9 +23,6 @@ _a:
 .core.ZXBASIC_USER_DATA_END:
 .core.__MAIN_PROGRAM__:
 .LABEL._10:
-		push hl
-	ld hl, 4
-	call .core.CHECK_BREAK
 .LABEL._20:
 	ld a, 1
 	ld (_a), a
@@ -119,5 +116,5 @@ NO_BREAK:
 	TS_BRK EQU 8020
 	    ENDP
 	    pop namespace
-#line 40 "break.bas"
+#line 37 "zx48k/break.bas"
 	END

tests/functional/zx48k/break_label0.asm

@@ -0,0 +1,111 @@
+	org 32768
+.core.__START_PROGRAM:
+	di
+	push ix
+	push iy
+	exx
+	push hl
+	exx
+	ld hl, 0
+	add hl, sp
+	ld (.core.__CALL_BACK__), hl
+	ei
+	jp .core.__MAIN_PROGRAM__
+.core.__CALL_BACK__:
+	DEFW 0
+.core.ZXBASIC_USER_DATA:
+	; Defines USER DATA Length in bytes
+.core.ZXBASIC_USER_DATA_LEN EQU .core.ZXBASIC_USER_DATA_END - .core.ZXBASIC_USER_DATA
+	.core.__LABEL__.ZXBASIC_USER_DATA_LEN EQU .core.ZXBASIC_USER_DATA_LEN
+	.core.__LABEL__.ZXBASIC_USER_DATA EQU .core.ZXBASIC_USER_DATA
+_a:
+	DEFB 00
+.core.ZXBASIC_USER_DATA_END:
+.core.__MAIN_PROGRAM__:
+	xor a
+	ld (_a), a
+		push hl
+	ld hl, 5
+	call .core.CHECK_BREAK
+.LABEL._test_label:
+	ld a, 1
+	ld (_a), a
+		push hl
+	ld hl, 7
+	call .core.CHECK_BREAK
+	ld hl, 0
+	ld b, h
+	ld c, l
+.core.__END_PROGRAM:
+	di
+	ld hl, (.core.__CALL_BACK__)
+	ld sp, hl
+	exx
+	pop hl
+	exx
+	pop iy
+	pop ix
+	ei
+	ret
+	;; --- end of user code ---
+#line 1 "/zxbasic/src/arch/zx48k/library-asm/break.asm"
+#line 1 "/zxbasic/src/arch/zx48k/library-asm/error.asm"
+	; Simple error control routines
+; vim:ts=4:et:
+	    push namespace core
+	ERR_NR    EQU    23610    ; Error code system variable
+	; Error code definitions (as in ZX spectrum manual)
+; Set error code with:
+	;    ld a, ERROR_CODE
+	;    ld (ERR_NR), a
+	ERROR_Ok                EQU    -1
+	ERROR_SubscriptWrong    EQU     2
+	ERROR_OutOfMemory       EQU     3
+	ERROR_OutOfScreen       EQU     4
+	ERROR_NumberTooBig      EQU     5
+	ERROR_InvalidArg        EQU     9
+	ERROR_IntOutOfRange     EQU    10
+	ERROR_NonsenseInBasic   EQU    11
+	ERROR_InvalidFileName   EQU    14
+	ERROR_InvalidColour     EQU    19
+	ERROR_BreakIntoProgram  EQU    20
+	ERROR_TapeLoadingErr    EQU    26
+	; Raises error using RST #8
+__ERROR:
+	    ld (__ERROR_CODE), a
+	    rst 8
+__ERROR_CODE:
+	    nop
+	    ret
+	; Sets the error system variable, but keeps running.
+	; Usually this instruction if followed by the END intermediate instruction.
+__STOP:
+	    ld (ERR_NR), a
+	    ret
+	    pop namespace
+#line 2 "/zxbasic/src/arch/zx48k/library-asm/break.asm"
+	; Check if BREAK is pressed
+	; Return if not. Else Raises
+	; L BREAK Into Program Error
+	; HL contains the line number we want to appear in the error msg.
+	    push namespace core
+CHECK_BREAK:
+	    PROC
+	    LOCAL PPC, TS_BRK, NO_BREAK
+	    push af
+	    call TS_BRK
+	    jr c, NO_BREAK
+	    ld (PPC), hl ; line num
+	    ld a, ERROR_BreakIntoProgram
+	    jp __ERROR   ; this stops the program and exits to BASIC
+NO_BREAK:
+	    pop af
+	    pop hl       ; ret address
+	    ex (sp), hl  ; puts it back into the stack and recovers initial HL
+	    ret
+	PPC EQU 23621
+	TS_BRK EQU 8020
+	    ENDP
+	    pop namespace
+#line 28 "zx48k/break_label0.bas"
+	END

tests/functional/zx48k/break_label0.bas

@@ -0,0 +1,8 @@
+#pragma enable_break = true
+
+DIM a as Ubyte
+
+LET a = 0
+test_label:
+LET a = 1
+