[opt] Fold {x == y} if {x} and {y} known-zero equivalent

aeneas/src/main/Version.v3

@@ -3,6 +3,6 @@
 
 // Updated by VCS scripts. DO NOT EDIT.
 component Version {
-	def version: string = "III-7.1682";
+	def version: string = "III-7.1683";
 	var buildData: string;
 }

aeneas/src/ssa/SsaOptimizer.v3

@@ -384,7 +384,7 @@ class SsaInstrReducer(context: SsaContext) extends SsaInstrMatcher {
 				if (x == y) return graph.trueConst();
 				var and = x.facts & y.facts, or = x.facts | y.facts;
 				if (Facts.NONE != (and & Fact.V_ZERO)) return graph.trueConst(); // 0 == 0 == true
-//TODO				if (ZERO_NON_ZERO == (or & ZERO_NON_ZERO)) return graph.falseConst(); // 0 == nonzero == false
+				if (ZERO_NON_ZERO == (or & ZERO_NON_ZERO)) return graph.falseConst(); // 0 == nonzero == false
 				if (ABOVE_BELOW_ZERO == (or & ABOVE_BELOW_ZERO)) return graph.falseConst(); // neg == pos == false
 			}
 			VariantEq => {

test/core/opt_nz00.v3

@@ -0,0 +1,5 @@
+//@execute 0=false; 1=false
+def main(a: int) -> bool {
+	return (a | 1) == (a & 0);
+}
+

test/core/opt_nz01.v3

@@ -1,6 +1,5 @@
 //@execute 0=false; 1=false
-component opt_nz01 {
-	def main(a: int) -> bool {
-		return (a | 1) == 0;
-	}
+def main(a: int) -> bool {
+	return (a | 1) == 0;
 }
+

test/core/opt_nz02.v3

@@ -1,6 +1,5 @@
 //@execute 0=true; 1=true
-component opt_nz02 {
-	def main(a: int) -> bool {
-		return (a | 1) != 0;
-	}
+def main(a: int) -> bool {
+	return (a | 1) != 0;
 }
+

test/core/opt_nz03.v3

@@ -0,0 +1,5 @@
+//@execute 0=false; -1=false
+def main(a: int) -> bool {
+	var x = if(a < 0, 1, 2);
+	return x == 0;
+}

test/core/opt_nz04.v3

@@ -0,0 +1,6 @@
+//@execute 0=false; -1=false
+def main(a: int) -> bool {
+	var x = if(a < 0, 1, 2);
+	var y = if(a > 0, a & 0, x & 0);
+	return x == y;
+}

test/core/opt_nz05.v3

@@ -0,0 +1,6 @@
+//@execute (0, 0)=true; (0, 1)=false; (1, 0)=false; (1, 1)=true
+def main(a: int, b: int) -> bool {
+	var x = if(a != 0, 1, 0);
+	var y = if(b != 0, 1, 0);
+	return x == y;
+}