Added minimal PHI clobber example.

src/main/java/dk/camelot64/kickc/TODO.txt

@@ -1,4 +1,5 @@
 Known Problems
+- Clobber can occur in PHI-statements. Example: scroll-clobber.kc. c#1/c#2 (A-register) is clobbered by //SEG18 [6] phi (byte*) main::nxt#4 = (const byte[]) TEXT#0 -- zpptrby1=cowo1
 
 Features
 - Add support for expressions in data initializers.

src/main/java/dk/camelot64/kickc/test/TestCompilationOutput.java

@@ -24,6 +24,10 @@ public class TestCompilationOutput extends TestCase {
       helper = new ReferenceHelper("dk/camelot64/kickc/test/ref/");
    }
 
+   public void testScrollClobber() throws IOException, URISyntaxException {
+      compileAndCompare("scroll-clobber");
+   }
+
    public void testHalfscii() throws IOException, URISyntaxException {
       compileAndCompare("halfscii");
    }

src/main/java/dk/camelot64/kickc/test/ref/scroll-clobber.asm

@@ -0,0 +1,31 @@
+  .const SCREEN = $400
+  .const SCROLL = $d016
+  TEXT: .text "01234567@"
+  jsr main
+main: {
+    .label nxt = 2
+    ldx #0
+    lda #<TEXT
+    sta nxt
+    lda #>TEXT
+    sta nxt+1
+  b1:
+    ldy #0
+    lda (nxt),y
+    cmp #'@'
+    bne b2
+    lda #<TEXT
+    sta nxt
+    lda #>TEXT
+    sta nxt+1
+    lda TEXT
+  b2:
+    inx
+    sta SCREEN,x
+    inc nxt
+    bne !+
+    inc nxt+1
+  !:
+    jmp b1
+    rts
+}

src/main/java/dk/camelot64/kickc/test/ref/scroll-clobber.cfg

@@ -0,0 +1,27 @@
+@begin: scope:[]  from
+  [0] call main param-assignment [ ]
+  to:@end
+@end: scope:[]  from @begin
+main: scope:[main]  from @begin
+  [1] phi() [ ]
+  to:main::@1
+main::@1: scope:[main]  from main main::@2
+  [2] (byte) main::i#3 ← phi( main/(byte) 0 main::@2/(byte) main::i#1 ) [ main::nxt#3 main::i#3 ]
+  [2] (byte*) main::nxt#3 ← phi( main/(const byte[]) TEXT#0 main::@2/(byte*) main::nxt#1 ) [ main::nxt#3 main::i#3 ]
+  [3] (byte) main::c#0 ← * (byte*) main::nxt#3 [ main::nxt#3 main::i#3 main::c#0 ]
+  [4] if((byte) main::c#0!=(byte) '@') goto main::@2 [ main::nxt#3 main::i#3 main::c#0 ]
+  to:main::@3
+main::@3: scope:[main]  from main::@1
+  [5] (byte) main::c#1 ← * (const byte[]) TEXT#0 [ main::i#3 main::c#1 ]
+  to:main::@2
+main::@2: scope:[main]  from main::@1 main::@3
+  [6] (byte*) main::nxt#4 ← phi( main::@1/(byte*) main::nxt#3 main::@3/(const byte[]) TEXT#0 ) [ main::i#3 main::c#2 main::nxt#4 ]
+  [6] (byte) main::c#2 ← phi( main::@1/(byte) main::c#0 main::@3/(byte) main::c#1 ) [ main::i#3 main::c#2 main::nxt#4 ]
+  [7] (byte) main::i#1 ← ++ (byte) main::i#3 [ main::i#1 main::c#2 main::nxt#4 ]
+  [8] *((const byte*) SCREEN#0 + (byte) main::i#1) ← (byte) main::c#2 [ main::i#1 main::nxt#4 ]
+  [9] (byte*) main::nxt#1 ← ++ (byte*) main::nxt#4 [ main::nxt#1 main::i#1 ]
+  [10] if(true) goto main::@1 [ main::nxt#1 main::i#1 ]
+  to:main::@return
+main::@return: scope:[main]  from main::@2
+  [11] return  [ ]
+  to:@return

src/main/java/dk/camelot64/kickc/test/ref/scroll-clobber.sym

@@ -0,0 +1,28 @@
+(label) @begin
+(label) @end
+(byte*) SCREEN
+(const byte*) SCREEN#0 SCREEN = (word) 1024
+(byte*) SCROLL
+(const byte*) SCROLL#0 SCROLL = (word) 53270
+(byte[]) TEXT
+(const byte[]) TEXT#0 TEXT = (string) "tst @"
+(void()) main()
+(label) main::@1
+(label) main::@2
+(label) main::@3
+(label) main::@return
+(byte) main::c
+(byte) main::c#0 reg byte a 16.5
+(byte) main::c#1 reg byte a 22.0
+(byte) main::c#2 reg byte a 16.5
+(byte) main::i
+(byte) main::i#1 reg byte x 8.25
+(byte) main::i#3 reg byte x 4.4
+(byte*) main::nxt
+(byte*) main::nxt#1 nxt zp ZP_PTR_BYTE:2 11.0
+(byte*) main::nxt#3 nxt zp ZP_PTR_BYTE:2 11.0
+(byte*) main::nxt#4 nxt zp ZP_PTR_BYTE:2 7.333333333333333
+
+reg byte x [ main::i#3 main::i#1 ]
+reg byte a [ main::c#2 main::c#0 main::c#1 ]
+zp ZP_PTR_BYTE:2 [ main::nxt#4 main::nxt#3 main::nxt#1 ]

src/main/java/dk/camelot64/kickc/test/scroll-clobber.kc

@@ -0,0 +1,18 @@
+byte* SCREEN = $0400;
+byte* SCROLL = $d016;
+byte[] TEXT = "tst @";
+main();
+
+void main() {
+    byte* nxt = TEXT;
+    byte i=0;
+    do {
+        byte c = *nxt;
+        if(c=='@') {
+           nxt = TEXT;
+           c = *nxt;
+        }
+        SCREEN[++i] = c;
+        nxt++;
+    } while (true)
+}