Minor simplification to phi optimization

aeneas/src/mach/MachLowering.v3

@@ -223,9 +223,6 @@ class SsaGraphNormalizer(context: SsaContext) {
 		i_old.setInputs(ai_new);
 		return i_old;
 	}
-	def normType(t: Type) -> TypeNorm;
-	def genSimpleVal(v: Val, tn: TypeNorm) -> Val;
-	def genValIntoArray(v: Val, tn: TypeNorm, dest: Array<Val>, index: int);
 	def normType1(t: Type) -> Type {
 		var tn = normType(t);
 		return if(tn != null, tn.newType, t);
@@ -234,7 +231,6 @@ class SsaGraphNormalizer(context: SsaContext) {
 		var tn = normType(t);
 		return tn != null && (tn.size != 1 || tn.newType != t);
 	}
-
 	def mapMultiReturn(i_old: SsaInstr, i_new: SsaInstr, tn: TypeNorm) {
 		if (tn == null || tn.size == 1) return map1(i_old, i_new);
 		if (tn.size == 0) return map0(i_old);
@@ -268,6 +264,10 @@ class SsaGraphNormalizer(context: SsaContext) {
 		}
 		return expr;
 	}
+	// ==== Required overrides ================================================
+	def normType(t: Type) -> TypeNorm;
+	def genSimpleVal(v: Val, tn: TypeNorm) -> Val;
+	def genValIntoArray(v: Val, tn: TypeNorm, dest: Array<Val>, index: int);
 }
 
 // Lowers Virgil code to machine level in-place by replacing object-level operations
@@ -415,7 +415,6 @@ class MachLowering(mach: MachProgram, compiler: Compiler, config: MachLoweringCo
 			return if(mt != t, TypeNorm.new(t, mt, null));
 		}
 	}
-
 	def normTypeTuple(t: Type) -> TupleNorm {
 		// TODO: cache flattened tuples which occur in returns
 		// flatten tuples

aeneas/src/main/Version.v3

@@ -3,6 +3,6 @@
 
 // Updated by VCS scripts. DO NOT EDIT.
 component Version {
-	def version: string = "III-9.1791";
+	def version: string = "III-9.1792";
 	var buildData: string;
 }

aeneas/src/ssa/SsaOptimizer.v3

@@ -391,22 +391,6 @@ class SsaInstrReducer(context: SsaContext) extends SsaInstrMatcher {
 			i = next;
 		}
 	}
-	def reducePhi(i: SsaPhi) -> bool {
-		var i0 = i.input0(), facts = i0.facts, same = true;
-		for (n = 1; n < i.inputs.length; n++) {
-			var iN = i.inputs[n].dest;
-			facts &= iN.facts;
-			if (iN != i0) same = false;
-		}
-		if (same) {
-			// phi(x, x, x...) => x
-			i.replace(i0);
-			return false;
-		}
-		i.facts |= facts;
-		return true;
-	}
-
 	def reduceInstr(i: SsaInstr) -> SsaInstr {
 		prev = i.prev;
 		match (i) {
@@ -1428,22 +1412,7 @@ class SsaCfOptimizer(context: SsaContext) {
 			killInstr(phi);
 			return true;
 		}
-		var facts = i0.facts, reduce = true;
-		for (i in inputs) {
-			var d = i.dest;
-			if (d != phi) {
-				facts = facts & d.facts;
-				if (d != i0) reduce = false;
-			}
-		}
-		if (reduce) {
-			phi.replace(i0); // the phi can be replaced by its (one) input
-			phi.remove();
-			return true;
-		} else {
-			phi.setFact(facts); // phi facts are the intersection of all input facts
-			return false;
-		}
+		return reducePhi(phi);
 	}
 	def optIf(block: SsaBlock, sw: SsaIf) {
 		var e = sw.inputs[0], v = e.dest;
@@ -1846,6 +1815,22 @@ class SsaCfOptimizer(context: SsaContext) {
 }
 class SwitchCmp(val: int, cmp: SsaInstr, end: SsaIf, tSucc: SsaCfEdge, fSucc: SsaCfEdge) { }
 
+def reducePhi(i_phi: SsaPhi) -> bool {
+	var i0 = i_phi.input0(), facts = i0.facts, same = true;
+	for (n = 1; n < i_phi.inputs.length; n++) {
+		var iN = i_phi.inputs[n].dest;
+		facts &= iN.facts;
+		if (iN != i0 && iN != i_phi) same = false;
+	}
+	if (same) {
+		// phi(x, phi, x...) => x
+		i_phi.replace(i0);
+		i_phi.remove();
+		return false;
+	}
+	i_phi.facts |= facts;
+	return true;
+}
 
 // Performs optimizations on loops.
 // 1. eliminate rendundant bounds checks for induction variables.

test/core/opt_phi00.v3

@@ -0,0 +1,8 @@
+//@execute 0=0; -11=-11
+def main(a: int) -> int {
+	var sum = a;
+	for (i < 10) {
+		sum = a; // phi for sum is recursive but redundant
+	}
+	return sum;
+}

test/core/opt_phi01.v3

@@ -1,10 +1,9 @@
 //@execute 1=1; 0=0
-component opt_phi01 {
-	def main(a: int) -> int {
-		var i = 0;
-		while (i < 1) i = i + 1;
-		i = a;
-		while (true) return i;
-		return i;
-	}
+def main(a: int) -> int {
+	var i = 0;
+	while (i < 1) i = i + 1;
+	i = a;
+	while (true) return i;
+	return i;
 }
+

test/core/opt_phi02.v3

@@ -1,10 +1,9 @@
 //@execute 1=3; 0=3
-component opt_phi02 {
-	def main(a: int) -> int {
-		var i = 0;
-		while (i < 1) i = i + 1;
-		i = 1;
-		while (true) return i + 2;
-		return i + 2;
-	}
+def main(a: int) -> int {
+	var i = 0;
+	while (i < 1) i = i + 1;
+	i = 1;
+	while (true) return i + 2;
+	return i + 2;
 }
+

test/core/opt_phi03.v3

@@ -1,11 +1,9 @@
 //@execute 1=1; 0=1
-component opt_phi03 {
-	def main(a: int) -> int {
-		var i = 0;
-		while (i < 1) i = i + 1;
-		i = 1;
-		while (i == 1) break;
-		if (i == 1) return 1;
-		return 2;
-	}
+def main(a: int) -> int {
+	var i = 0;
+	while (i < 1) i = i + 1;
+	i = 1;
+	while (i == 1) break;
+	if (i == 1) return 1;
+	return 2;
 }

test/core/opt_phi04.v3

@@ -0,0 +1,8 @@
+//@execute 0=0; -11=-11
+def main(a: int) -> int {
+	var sum = a;
+	for (i < 10) {
+		sum = sum; // phi for sum is recursive but redundant
+	}
+	return sum;
+}