shithub: scc

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Fix algebraic identities about logical operators

If the right part of a logic operator is a constant (which comes from
the folding of some comparision), then the logic operator can be
changed to a comma operator.

--- a/cc1/fold.c

+++ b/cc1/fold.c

@@ -377,10 +377,8 @@

 }

 /*

- * i || 0 => i,0

- * i || 1 => i

- * i && 0 => i,0

- * i && 1 => i

+ * i || k => i,k

+ * i && k => i,k

  * i >> 0 => i

  * i << 0 => i

  * i + 0  => i

@@ -406,17 +404,10 @@

 	istrue = !iszero && rp->constant;

 	switch (*op) {

+	case OAND:

 	case OOR:

-		if (istrue)

+		if (rp->constant)

 			goto change_to_comma;

-		if (iszero)

-			break;

-		return NULL;

-	case OAND:

-		if (iszero)

-			goto change_to_comma;

-		if (istrue)

-			break;

 		return NULL;

 	case OSHL:

 	case OSHR: