Fixes #135: Optimization does not spot variable changed inside loop

mindcode/src/main/java/info/teksol/mindcode/compiler/optimization/BaseOptimizer.java

@@ -36,7 +36,7 @@
  */
 abstract class BaseOptimizer extends AbstractOptimizer {
     protected static final boolean TRACE = false;
-    protected static final boolean DEBUG_PRINT = TRACE;
+    protected static final boolean DEBUG_PRINT = false;
 
     protected int modifications = 0;
     protected int insertions = 0;

mindcode/src/main/java/info/teksol/mindcode/compiler/optimization/DataFlowOptimizer.java

@@ -8,6 +8,7 @@
 import info.teksol.mindcode.compiler.generator.CallGraph;
 import info.teksol.mindcode.compiler.instructions.*;
 import info.teksol.mindcode.compiler.optimization.DataFlowVariableStates.VariableStates;
+import info.teksol.mindcode.compiler.optimization.DataFlowVariableStates.VariableValue;
 import info.teksol.mindcode.compiler.optimization.OptimizationContext.LogicIterator;
 import info.teksol.mindcode.logic.*;
 
@@ -168,7 +169,7 @@ private void replaceInstruction(LogicInstruction instruction) {
         } else if (instruction instanceof SetInstruction set) {
             // Specific optimization to streamline self-modifying statements in recursive calls
             if (canEliminate(set, set.getResult()) && set.getValue().isTemporaryVariable()) {
-                VariableStates.VariableValue val = variableStates.findVariableValue(set.getValue());
+                VariableValue val = variableStates.findVariableValue(set.getValue());
                 if (val != null && val.isExpression() && val.getInstruction() instanceof OpInstruction op) {
                     if (op.inputArgumentsStream().anyMatch(set.getResult()::equals)) {
                         OpInstruction newInstruction = op.withContext(set.getAstContext()).withResult(set.getResult());
@@ -754,6 +755,8 @@ private VariableStates resolveLabel(VariableStates variableStates, LogicLabel la
         return variableStates;
     }
 
+    private int counter = 0;
+
     /**
      * Processes a single instruction.
      *
@@ -768,7 +771,8 @@ private VariableStates processInstruction(VariableStates variableStates, LogicIn
         Objects.requireNonNull(variableStates);
         Objects.requireNonNull(instruction);
 
-        trace(() -> "Processing instruction #" + instructionIndex(instruction) +
+        counter++;
+        trace(() -> "*" + counter + " Processing instruction #" + instructionIndex(instruction) +
                 ": " + LogicInstructionPrinter.toString(instructionProcessor, instruction));
 
         switch (instruction) {

mindcode/src/main/java/info/teksol/mindcode/compiler/optimization/OptimizerExpressionEvaluator.java

@@ -4,7 +4,7 @@
 import info.teksol.mindcode.compiler.instructions.JumpInstruction;
 import info.teksol.mindcode.compiler.instructions.OpInstruction;
 import info.teksol.mindcode.compiler.optimization.DataFlowVariableStates.VariableStates;
-import info.teksol.mindcode.compiler.optimization.DataFlowVariableStates.VariableStates.VariableValue;
+import info.teksol.mindcode.compiler.optimization.DataFlowVariableStates.VariableValue;
 import info.teksol.mindcode.logic.*;
 import info.teksol.mindcode.processor.ExpressionEvaluator;
 import info.teksol.mindcode.processor.MindustryValue;

mindcode/src/test/java/info/teksol/mindcode/compiler/optimization/DataFlowOptimizerTest.java

@@ -677,6 +677,38 @@ void handlesNonConstantExpressions() {
                 createInstruction(JUMP, var(1000), "always")
         );
     }
+
+    @Test
+    void properlyInvalidatesExpressions() {
+        assertCompilesTo("""
+                        a = rand(10) > 5
+                        b = a > 5
+                        c = b or a < 5
+                        d = a
+
+                        while true
+                            if c
+                                d += 1
+                                c = b or d < 5
+                            end
+                        end
+                        """,
+                createInstruction(OP, "rand", var(0), "10"),
+                createInstruction(OP, "greaterThan", "a", var(0), "5"),
+                createInstruction(OP, "greaterThan", "b", "a", "5"),
+                createInstruction(OP, "lessThan", var(3), "a", "5"),
+                createInstruction(OP, "or", "c", "b", var(3)),
+                createInstruction(SET, "d", "a"),
+                createInstruction(LABEL, var(1000)),
+                createInstruction(JUMP, var(1000), "equal", "c", "false"),
+                createInstruction(OP, "add", "d", "d", "1"),
+                createInstruction(OP, "lessThan", var(4), "d", "5"),
+                createInstruction(OP, "or", "c", "b", var(4)),
+                createInstruction(JUMP, var(1000), "always")
+
+
+        );
+    }
     //</editor-fold>
 
     //<editor-fold desc="Exit points">

mindcode/src/test/resources/info/teksol/mindcode/processor/algorithms/bitmap-get-set.log

@@ -3,7 +3,7 @@
      1 instructions eliminated by Dead Code Elimination (3 iterations).
     16 instructions eliminated by Single Step Elimination (5 iterations).
      1 instructions modified by If Expression Optimization (3 iterations).
-    40 instructions eliminated by Data Flow Optimization (3 passes, 13 iterations).
+    40 instructions eliminated by Data Flow Optimization (3 passes, 12 iterations).
      2 instructions eliminated by Loop Optimization (3 iterations).
      2 loops improved by Loop Optimization.
    219 instructions added by Loop Unrolling (5 iterations).
@@ -1187,10 +1187,12 @@ Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 2 (-1
 +  299 read __tmp9 BITMAP __tmp3
    300 op mod __tmp11 14 BITS
 -    * op shl __tmp12 1 __tmp11
+-    * op and __tmp8 __tmp9 __tmp12
 +  301 op shl __tmp12 1 __tmp4
-   302 op and __tmp8 __tmp9 __tmp12
++  302 op and __tmp8 __tmp9 __tmp5
    303 label __label120
    304 jump __label121 equal __tmp8 false
+   305 set __tmp14 1
 
    307 label __label121
    308 print __tmp14
@@ -1207,26 +1209,14 @@ Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 2 (-1
    325 label __label7
    326 end
 
-Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 3 (-2 instructions):
+Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 3 (-3 instructions):
 
    295 label __label118
    296 set __tmp14 0
    297 label __label119
 -    * op idiv __tmp10 14 BITS
    298 read __tmp9 BITMAP __tmp3
 -    * op mod __tmp11 14 BITS
-   299 op shl __tmp12 1 __tmp4
--    * op and __tmp8 __tmp9 __tmp12
-+  300 op and __tmp8 __tmp9 __tmp5
-   301 label __label120
-   302 jump __label121 equal __tmp8 false
-   303 set __tmp14 1
-
-Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 4 (-1 instructions):
-
-   296 set __tmp14 0
-   297 label __label119
-   298 read __tmp9 BITMAP __tmp3
 -    * op shl __tmp12 1 __tmp4
    299 op and __tmp8 __tmp9 __tmp5
    300 label __label120

mindcode/src/test/resources/info/teksol/mindcode/processor/optimizer/OptimizerTest.txt

@@ -3,6 +3,7 @@ detector-00.mnd:                          173 instructions, source CRC FE8119939
 factory-monitor-00.mnd:                   357 instructions, source CRC 735D793DE9291346, compiled CRC BD9B6E1EB255B21C
 factory-monitor-silicon-00.mnd:           291 instructions, source CRC A359A3FF5FB80033, compiled CRC E7389555BDC3125C
 factory-monitor-surge-alloy-00.mnd:       194 instructions, source CRC FB39BBCB30FDEA11, compiled CRC E93022DEEB3840D3
+impact-reactor-logic-00.mnd:              882 instructions, source CRC 5FE7F84A717D715F, compiled CRC 764C0E3D998F1DC1
 instant-overdrive-dome-00.mnd:            633 instructions, source CRC A1AE234B22C7A682, compiled CRC 26AAE5623D20AF94
 item-counter-00.mnd:                       99 instructions, source CRC 4D90F2B3A3A52A57, compiled CRC 102983144F395C25
 item-counter-micro-00.mnd:                143 instructions, source CRC 38F77F7CF7606263, compiled CRC 390700627A884E47

mindcode/src/test/resources/info/teksol/mindcode/processor/optimizer/OptimizerTest_timing.txt

@@ -1,8 +1,9 @@
-breakout-00.mnd:                        : parse:        400 ms, compile:          0 ms, optimize:          0 ms
+breakout-00.mnd:                        : parse:        200 ms, compile:          0 ms, optimize:          0 ms
 detector-00.mnd:                        : parse:          0 ms, compile:          0 ms, optimize:          0 ms
 factory-monitor-00.mnd:                 : parse:        400 ms, compile:          0 ms, optimize:        200 ms
-factory-monitor-silicon-00.mnd:         : parse:        400 ms, compile:          0 ms, optimize:          0 ms
+factory-monitor-silicon-00.mnd:         : parse:        400 ms, compile:          0 ms, optimize:        200 ms
 factory-monitor-surge-alloy-00.mnd:     : parse:        200 ms, compile:          0 ms, optimize:          0 ms
+impact-reactor-logic-00.mnd:            : parse:        400 ms, compile:          0 ms, optimize:        800 ms
 instant-overdrive-dome-00.mnd:          : parse:        200 ms, compile:          0 ms, optimize:        200 ms
 item-counter-00.mnd:                    : parse:        200 ms, compile:          0 ms, optimize:          0 ms
 item-counter-micro-00.mnd:              : parse:        200 ms, compile:          0 ms, optimize:          0 ms
@@ -14,12 +15,12 @@ level-meter-00.mnd:                     : parse:        200 ms, compile:
 mass-driver-monitor-00.mnd:             : parse:        200 ms, compile:          0 ms, optimize:          0 ms
 mass-driver-monitor-surge-alloy-00.mnd: : parse:        200 ms, compile:          0 ms, optimize:          0 ms
 reactor-control-00.mnd:                 : parse:      1,200 ms, compile:          0 ms, optimize:        200 ms
-reactor-control-battery-level-00.mnd:   : parse:        400 ms, compile:          0 ms, optimize:        200 ms
+reactor-control-battery-level-00.mnd:   : parse:        200 ms, compile:          0 ms, optimize:        200 ms
 regulator-00.mnd:                       : parse:        200 ms, compile:          0 ms, optimize:          0 ms
 remote-vault-00.mnd:                    : parse:          0 ms, compile:          0 ms, optimize:          0 ms
-storage-display-00.mnd:                 : parse:        200 ms, compile:          0 ms, optimize:        200 ms
+storage-display-00.mnd:                 : parse:        200 ms, compile:          0 ms, optimize:        400 ms
 unit-housekeeping-00.mnd:               : parse:          0 ms, compile:          0 ms, optimize:          0 ms
 unit-speed-00.mnd:                      : parse:          0 ms, compile:          0 ms, optimize:          0 ms
-unit-transport-00.mnd:                  : parse:        600 ms, compile:          0 ms, optimize:        400 ms
+unit-transport-00.mnd:                  : parse:        600 ms, compile:          0 ms, optimize:        600 ms
 unit-transport-flow-rate-00.mnd:        : parse:        200 ms, compile:          0 ms, optimize:          0 ms
-unit-transport-single-00.mnd:           : parse:        200 ms, compile:          0 ms, optimize:          0 ms
+unit-transport-single-00.mnd:           : parse:        200 ms, compile:          0 ms, optimize:        200 ms

mindcode/src/test/resources/info/teksol/mindcode/processor/optimizer/factory-monitor-00.log

@@ -5,7 +5,7 @@
     15 instructions eliminated by Single Step Elimination (2 passes, 6 iterations).
      1 instructions modified by Expression Optimization (3 iterations).
      8 instructions eliminated by If Expression Optimization (3 iterations).
-    16 instructions eliminated by Data Flow Optimization (3 passes, 12 iterations).
+    16 instructions eliminated by Data Flow Optimization (3 passes, 11 iterations).
      4 instructions added by Loop Optimization (3 iterations).
      4 loops improved by Loop Optimization.
     11 instructions eliminated by Jump Straightening (2 passes, 4 iterations).
@@ -1476,30 +1476,20 @@ Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 1:
    174 op equal __tmp0 DISPLAY null
    175 op equal __tmp1 TYPE null
 -    * op or __tmp2 __tmp0 __tmp1
+-    * jump __label86 notEqual __tmp2 false
 +  176 op or __tmp2 __tmp25 __tmp26
-   177 jump __label86 notEqual __tmp2 false
++  177 jump __label86 notEqual __tmp27 false
    178 label __label2
    179 sensor __tmp29 DISPLAY @type
+   180 jump __label29 notEqual __tmp29 @logic-display
 
-Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 2 (-2 instructions):
+Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 2 (-3 instructions):
 
    171 label __label28
    172 printflush MESSAGE
    173 label __label1
 -    * op equal __tmp0 DISPLAY null
 -    * op equal __tmp1 TYPE null
-   174 op or __tmp2 __tmp25 __tmp26
--    * jump __label86 notEqual __tmp2 false
-+  175 jump __label86 notEqual __tmp27 false
-   176 label __label2
-   177 sensor __tmp29 DISPLAY @type
-   178 jump __label29 notEqual __tmp29 @logic-display
-
-Modifications by Iterated phase, Data Flow Optimization, pass 1, iteration 3 (-1 instructions):
-
-   171 label __label28
-   172 printflush MESSAGE
-   173 label __label1
 -    * op or __tmp2 __tmp25 __tmp26
    174 jump __label86 notEqual __tmp27 false
    175 label __label2