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Simplify boolean expressions in Java AST #10279

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zbynek merged 2 commits into from
Apr 23, 2026
Merged

Simplify boolean expressions in Java AST #10279

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dbf7dec
Simplify boolean expressions in Java AST
zbynek Feb 20, 2026
54102dd
Add test cases, code style
zbynek Feb 24, 2026
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11 changes: 6 additions & 5 deletions dev/core/src/com/google/gwt/dev/jjs/impl/Simplifier.java
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Original file line number Diff line number Diff line change
Expand Up @@ -429,9 +429,10 @@ public static JExpression simplifyAnd(JBinaryOperation expression) {
if (rhs instanceof JBooleanLiteral) {
if (((JBooleanLiteral) rhs).getValue()) {
return lhs;
} else if (!lhs.hasSideEffects()) {
// Do not remove lhs if it had side effects
return rhs;
} else {
// if side effect, allow rewriting a() && false && b() -> (a(), false) && b()
// -> (a(), false && b()) -> (a(), false)
return lhs.hasSideEffects() ? new JMultiExpression(info, lhs, rhs) : rhs;
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}
}

Expand Down Expand Up @@ -482,8 +483,8 @@ public static JExpression simplifyOr(JBinaryOperation expression) {
if (rhs instanceof JBooleanLiteral) {
if (!((JBooleanLiteral) rhs).getValue()) {
return lhs;
} else if (!lhs.hasSideEffects()) {
return rhs;
} else {
return lhs.hasSideEffects() ? new JMultiExpression(info, lhs, rhs) : rhs;
}
}
return expression;
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8 changes: 8 additions & 0 deletions dev/core/test/com/google/gwt/dev/jjs/impl/DeadCodeEliminationTest.java
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Expand Up @@ -298,8 +298,10 @@ public void testCommuteMultiExpression() throws Exception {
+ "static int f1;"
+ "static A createA() { A.f1 = 1; return new A(); } "
+ "static boolean booleanWithSideEffects() { createA(); return true;}"
+ "static boolean randomBooleanWithSideEffects() { createA(); return random() > .5;}"
+ "static boolean booleanWithoutSideEffects() { return true;}"
+ "static int arithmeticWithSideEffects() { createA(); return 4;}"
+ "static native double random() /*-{ }-*/;"
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+ "}");

optimizeExpressions(false, "boolean", "true && A.booleanWithoutSideEffects()")
Expand All @@ -311,6 +313,12 @@ public void testCommuteMultiExpression() throws Exception {
optimizeExpressions(false, "boolean", "false && A.booleanWithSideEffects()")
.intoString("return false;");

optimizeExpressions(false, "int", "A.randomBooleanWithSideEffects() && false && A.randomBooleanWithSideEffects() ? 1 : 2")
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.intoString("return (EntryPoint$A.f1 = 1, new EntryPoint$A(), (EntryPoint$A.random() > 0.5, 2));");

optimizeExpressions(false, "int", "A.randomBooleanWithSideEffects() || true || A.randomBooleanWithSideEffects() ? 1 : 2")
.intoString("return (EntryPoint$A.f1 = 1, new EntryPoint$A(), (EntryPoint$A.random() > 0.5, 1));");

optimizeExpressions(false, "int", "3 + A.arithmeticWithSideEffects()")
.intoString("return (EntryPoint$A.f1 = 1, new EntryPoint$A(), 7);");
}
Expand Down