[unbox] Fix folding of if-cascade (#362)

Author: titzer

aeneas/src/mach/MachLowering.v3

@@ -1009,7 +1009,7 @@ class MachLowering(mach: MachProgram, compiler: Compiler, config: MachLoweringCo
 			i_cmp2.facts |= Facts.O_NO_NAN_CHECK; // NaN handled by first check
 			ifc.addCase(i_cmp2);
 			ifc.endCase(i_false);
-			ifc.addElse();
+			ifc.addElse(); // TODO: suspicious
 			var i_cmp = genIntTruncFEqual(i_old.source, ft, ett, i_x);
 			ifc.endCase(i_cmp);
 			var i_new = ifc.finish();
@@ -1042,7 +1042,7 @@ class MachLowering(mach: MachProgram, compiler: Compiler, config: MachLoweringCo
 		var i_gteq = apply(i_old.source, ft.opcache().opGteq, [i_x, i_maxf]);
 		ifc.addCase(i_gteq);
 		ifc.endCase(i_false);
-		ifc.addElse();
+		ifc.addElse(); // TODO: suspicious addElse
 		var i_cmp = genIntTruncFEqual(i_old.source, ft, ett, i_x);
 		ifc.endCase(i_cmp);
 		var i_new = ifc.finish();

aeneas/src/main/Version.v3

@@ -3,6 +3,6 @@
 
 // Updated by VCS scripts. DO NOT EDIT.
 component Version {
-	def version: string = "III-9.1801";
+	def version: string = "III-9.1802";
 	var buildData: string;
 }

aeneas/src/ssa/SsaBuilder.v3

@@ -647,8 +647,10 @@ class SsaBuilder {
 	}
 	// ClassAlloc[new](args)
 	def opClassAlloc(m: IrSpec, x: Array<SsaInstr>) -> SsaInstr {
-		if (m.member == null) return add(V3Op.newEmptyClassAlloc(m.receiver), Ssa.NO_INSTRS, Fact.V_NON_ZERO);
-		return add(V3Op.newClassAlloc(m), x, Fact.V_NON_ZERO);
+		var facts: Fact.set = Fact.V_NON_ZERO;
+//TODO		if (V3.isVariant(m.receiver)) facts |= Fact.O_PURE;
+		if (m.member == null) return add(V3Op.newEmptyClassAlloc(m.receiver), Ssa.NO_INSTRS, facts);
+		return add(V3Op.newClassAlloc(m), x, facts);
 	}
 	// (Component|Class|Variant)GetField[f](x)
 	def opGetField(f: IrSpec, x: SsaInstr) -> SsaInstr {
@@ -875,29 +877,22 @@ class SsaIfCascade {
 		fblock = null;
 	}
 	def endCase(val: SsaInstr) {
-		if (builder.end) return;
-		if (varType != null) {
-			if (val == null) builder.context.fail("SsaIfCascade variable must be non-null on this path");
-			phiInputs.put(val);
+		if (!builder.end) {
+			if (varType != null) {
+				if (val == null) builder.context.fail("SsaIfCascade variable must be non-null on this path");
+				phiInputs.put(val);
+			}
+			builder.addGoto(merge);
 		}
-		builder.addGoto(merge);
 		at(fblock);
 	}
 	private def addIf0(cond: SsaInstr, not: bool) {
 		if (builder.end) return;
 		var tb = SsaBlock.new(), fb = SsaBlock.new();
 		if (not) builder.addIf(cond, fb, tb);
 		else builder.addIf(cond, tb, fb);
-		if (tb.preds.length == 0) { // true case eliminated
-			at(fb);
-			fblock = null;
-		} else if (fb.preds.length == 0) { // false case eliminated
-			at(tb);
-			fblock = null;
-		} else {
-			at(tb);
-			fblock = fb;
-		}
+		at(tb);
+		fblock = fb;
 	}
 	def finish() -> SsaInstr {
 		if (fblock != null) builder.context.fail("SsaIfCascade: ended before else clause");

doc/aeneas-issues.txt

@@ -27,10 +27,13 @@ ______ ______ __   _ ______ ______ ______    _____ ______ ______ _    _ ______ _
 
 -- priority (primarily for Wizard) -----
   new type representation
+  TypeSystem.computeCast
   -target=wasmgc
   unbox and pack variants
   canonicalize equivalent variant records
   threads
+  fix and turn on inlining and -O3
+  fold using SSA interpreter
 
 -- wasm[gc] issues -----
   new type representation for structs, arrays, funcs

test/float/query02.v3

@@ -0,0 +1,7 @@
+//@execute -1=false; 1=true
+var f = 0.1f;
+var g = 33f;
+
+def main(a: int) -> bool {
+	return if(a < 0, int.?(f), int.?(g));
+}

test/float/query03.v3

@@ -0,0 +1,7 @@
+//@execute -1=false; 1=true
+var f = 0.1d;
+var g = 33d;
+
+def main(a: int) -> bool {
+	return if(a < 0, int.?(f), int.?(g));
+}

test/variants/ub_const00.v3

@@ -0,0 +1,11 @@
+//@execute =13
+type A #unboxed {
+	case X;
+	case Y(x: int);
+}
+
+def main() -> int {
+	var a = A.Y(13);
+	return getx(a);
+}
+def getx = A.Y.x;

test/variants/ub_const01.v3

@@ -0,0 +1,11 @@
+//@execute =13
+type A #unboxed {
+	case X;
+	case Y(x: int);
+}
+
+def main() -> int {
+	var a = [A.Y(13), A.Y(13)];
+	return getx(a[0]);
+}
+def getx = A.Y.x;

test/variants/ub_const02.v3

@@ -0,0 +1,16 @@
+//@execute =13
+type A #unboxed {
+	case X;
+	case Y(x: int);
+}
+
+def main() -> int {
+	var a = A.Y(13);
+	return getx(a);
+}
+def getx(a: A) -> int {
+	match (a) {
+		X => return 11;
+		Y(x) => return x;
+	}
+}

test/variants/ub_const03.v3

@@ -0,0 +1,12 @@
+//@execute =true
+type A {
+	case X;
+	case Y(x: int);
+}
+
+var x = A.Y(14);
+var y = A.Y(14);
+
+def main() -> bool {
+	return x == y;
+}