From: Andrew Pinski <apinski@marvell.com>
Date: Sat, 1 Jul 2023 02:22:48 +0000 (-0700)
Subject: PR 110487: `(a !=/== CST1 ? CST2 : CST3)` pattern for type safety
X-Git-Tag: basepoints/gcc-15~7840
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71b68cc559b5d30d07e6b507df7cc6d008f56aad;p=thirdparty%2Fgcc.git

PR 110487: `(a !=/== CST1 ? CST2 : CST3)` pattern for type safety

The problem here is we might produce some values out of the type's
min/max (and/or valid values, e.g. signed booleans). The fix is to
use an integer type which has the same precision and signedness
as the original type.

Note two_value_replacement in phiopt had the same issue in previous
versions; though I don't know if a problem will show up there.

OK? Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	PR tree-optimization/110487
	* match.pd (a !=/== CST1 ? CST2 : CST3): Always
	build a nonstandard integer and use that.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index 637d22ccefdc..8543f777a28e 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4799,24 +4799,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        tree type1;
        if ((eqne == EQ_EXPR) ^ (wi::to_wide (@1) == min))
          std::swap (arg0, arg1);
-       if (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (type))
-	 {
-	   /* Avoid performing the arithmetics in bool type which has different
-	      semantics, otherwise prefer unsigned types from the two with
-	     the same precision.  */
-	   if (TREE_CODE (TREE_TYPE (arg0)) == BOOLEAN_TYPE
-	       || !TYPE_UNSIGNED (type))
-	     type1 = TREE_TYPE (@0);
-	   else
-	     type1 = TREE_TYPE (arg0);
-	 }
-       else if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type))
+       if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type))
 	 type1 = TREE_TYPE (@0);
        else
 	 type1 = type;
-       min = wide_int::from (min, TYPE_PRECISION (type1),
+       auto prec = TYPE_PRECISION (type1);
+       auto unsign = TYPE_UNSIGNED (type1);
+       type1 = build_nonstandard_integer_type (prec, unsign);
+       min = wide_int::from (min, prec,
 			     TYPE_SIGN (TREE_TYPE (@0)));
-       wide_int a = wide_int::from (wi::to_wide (arg0), TYPE_PRECISION (type1),
+       wide_int a = wide_int::from (wi::to_wide (arg0), prec,
 				    TYPE_SIGN (type));
        enum tree_code code;
        wi::overflow_type ovf;
@@ -4824,7 +4816,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	 {
 	   code = PLUS_EXPR;
 	   a -= min;
-	   if (!TYPE_UNSIGNED (type1))
+	   if (!unsign)
 	     {
 	       /* lhs is known to be in range [min, min+1] and we want to add a
 		  to it.  Check if that operation can overflow for those 2 values
@@ -4838,7 +4830,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	 {
 	   code = MINUS_EXPR;
 	   a += min;
-	   if (!TYPE_UNSIGNED (type1))
+	   if (!unsign)
 	     {
 	       /* lhs is known to be in range [min, min+1] and we want to subtract
 		  it from a.  Check if that operation can overflow for those 2