Fix break statement stack leftover

docs/sslc_readme.md

@@ -348,6 +348,9 @@ There are several changes in this version of sslc which may result in problems f
 
 ### Changelog
 
+**sfall 4.5:**
+- fixed stack leftover from the `break` statement
+
 **sfall 4.4.7:**
 - added Linux & WebAssembly builds
 

gencode.c

@@ -28,14 +28,11 @@ static int startOffset;
 
 typedef struct {
 	int startPos;
-	int numBreaks;
 	int numContinue;
 } LoopInfo;
 
 LoopInfo loopStack[100]; // pointers to beginning of while loops
 int loopStackPos = 0;
-int breakStack[2048]; // pointers to arguments to JMP (break statements)
-int breakStackPos = 0;
 int continueStack[2048]; // pointers to arguments to JMP (continue statements)
 int continueStackPos = 0;
 
@@ -712,7 +709,6 @@ static int writeStatement(NodeList *n, int i, FILE *f) {
 			writeInt(0, f);
 			top = outputTell(f);
 			loopStack[++loopStackPos].startPos = top;
-			loopStack[loopStackPos].numBreaks = 0;
 			loopStack[loopStackPos].numContinue = 0;
 			i = writeExpression(n, i+1, f);
 			writeOp(O_WHILE, f);
@@ -734,9 +730,6 @@ static int writeStatement(NodeList *n, int i, FILE *f) {
 			pos = outputTell(f);
 			patchOffset(falseAddr+OPCODE_SIZE, pos, f);
 
-			for (j = 0; j < loopStack[loopStackPos].numBreaks; j++) { // for each break, change it's JMP argument to proper address
-				patchOffset(breakStack[breakStackPos--] + OPCODE_SIZE, pos, f);
-			}
 			continueStackPos -= loopStack[loopStackPos].numContinue; // remove all "continue" pointers found in current loop from the stack,
 																     // this will only apply to "WHILE" loops
 			loopStackPos--;
@@ -849,9 +842,10 @@ static int writeStatement(NodeList *n, int i, FILE *f) {
 			i++;
 			break;
 		case T_BREAK:
-			loopStack[loopStackPos].numBreaks++;
-			breakStack[++breakStackPos] = outputTell(f); // address will be patched to point to exit from loop
-			writeInt(0, f);
+			// "break" statement is only allowed inside for/foreach/while loops.
+			// All of them are implemented using O_WHILE which requires stack
+			// to have an address where to jump when condition is false.
+			// So we just using this address to jump to the end of loop.
 			writeOp(O_JMP, f);
 			i++;
 			break;

resource.h

@@ -9,7 +9,7 @@
 #define VERSION_BUILD 4
 #define VERSION_REV 0
 
-#define VERSION_STRING "4.4.7"
+#define VERSION_STRING "4.5"
 
 #ifdef BUILDING_DLL
 #define FILE_STRING "parser.dll"

test/embedded/successful/gl_break_statement.returncode.expected

@@ -0,0 +1 @@
+0

test/embedded/successful/gl_break_statement.ssl

@@ -0,0 +1,100 @@
+procedure some_noop(variable param) begin
+end
+
+procedure test_loops() begin
+    variable i;
+
+    display_msg("Break in while loop...");
+    i = 0;
+    while (i < 5) do begin
+        call some_noop("while loop begin");
+        if i == 2 then begin
+            break;
+        end
+        i++;
+        call some_noop("while loop end");
+    end
+
+    display_msg("Continue in while loop...");
+    i = 0;
+    while (i < 5) do begin
+        call some_noop("while loop begin");
+        if i == 2 then begin
+            i += 2;
+            continue;
+        end
+        i++;
+        call some_noop("while loop end");
+    end
+
+    display_msg("Break in for loop...");
+    for (i := 0; i < 5; i++) begin
+        call some_noop("for loop begin");
+        if i == 2 then begin
+            break;
+        end
+        call some_noop("for loop end");
+    end
+
+    display_msg("Continue in for loop...");
+    for (i := 0; i < 5; i++) begin
+        call some_noop("for loop begin");
+        if i == 2 then begin
+            continue;
+        end
+        call some_noop("for loop end");
+    end    
+
+    variable arr := [1, 2, 3, 4, 5];
+    display_msg("Break in foreach loop...");
+    foreach (i in arr) begin
+        call some_noop("foreach loop begin");
+        if i == 2 then begin
+            break;
+        end
+        call some_noop("foreach loop end");
+    end
+    display_msg("Continue in foreach loop...");
+    foreach (i in arr) begin
+        call some_noop("foreach loop begin");
+        if i == 2 then begin
+            continue;
+        end
+        call some_noop("foreach loop end");
+    end
+
+
+    display_msg("End of testing break/continue in loops");
+end  
+
+procedure test_nested_loop begin
+    display_msg("Testing break in nested loop...");
+    variable i, value;
+    for (i := 0; i < 5; i++) begin
+        display_msg("======== Item: " + i);
+        if i == 1 then begin
+            value = 1;
+        end else begin
+            value = 0;
+        end
+        display_msg("Value: " + value);
+        if (value != 0) then begin
+            display_msg("Interesting item: " + i);
+            while (value != 0) do begin
+                display_msg("While loop for item: " + i);
+                break; // should do nothing
+                display_msg("This should not be displayed for item: " + i); // Never displayed
+            end
+            display_msg("After while loop for item: " + i + ", value: " + value);
+        end else begin
+            display_msg("Not interesting item: " + i);
+        end
+        display_msg("End of item " + i);
+    end
+    display_msg("Finished testing nesting loops.");
+end
+
+procedure start begin
+    call test_loops();
+    call test_nested_loop();
+end

test/embedded/successful/gl_break_statement.stdout.expected

@@ -0,0 +1,13 @@
+Set include directory: ../include
+Compiling gl_break_statement.ssl
+[Message] <gl_break_statement.ssl>:1:42: Eliminating variable id 0
+[Message] <gl_break_statement.ssl>:8:6: Using constant variable store for initializer
+[Message] <gl_break_statement.ssl>:8:8: Eating dead store to variable 0
+[Message] <gl_break_statement.ssl>:50:23: Using constant variable store for initializer
+[Message] <gl_break_statement.ssl>:50:23: Eating dead store to variable 3
+[Message] <gl_break_statement.ssl>:58:23: Using constant variable store for initializer
+[Message] <gl_break_statement.ssl>:58:23: Eating dead store to variable 6
+[Message] <gl_break_statement.ssl>:73:11: Using constant variable store for initializer
+[Message] <gl_break_statement.ssl>:73:14: Eating dead store to variable 0
+[Message] <gl_break_statement.ssl>:86:28: Eating statement hidden by return
+[Message] <none>:-1: Removing unused string 'This should not be displayed for item: ' from program stringspace