From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, 20 Jan 2025 09:24:18 +0000 (+0100)
Subject: tree-ssa-dce: Fix calloc handling [PR118224]
X-Git-Tag: basepoints/gcc-16~2497
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d882e48d48bf300941c3610c5af157c64ccf0a84;p=thirdparty%2Fgcc.git

tree-ssa-dce: Fix calloc handling [PR118224]

As reported by Dimitar, this should have been a multiplication, but wasn't
caught because in the test (~(__SIZE_TYPE__) 0) / 2 is the largest accepted
size and so adding 3 to it also resulted in "overflow".

The following patch adds one subtest to really verify it is a multiplication
and fixes the operation.

2025-01-20  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/118224
	* tree-ssa-dce.cc (is_removable_allocation_p): Multiply a1 by a2
	instead of adding it.

	* gcc.dg/pr118224.c: New test.
---

diff --git a/gcc/testsuite/gcc.dg/pr118224.c b/gcc/testsuite/gcc.dg/pr118224.c
index 683f4dc8f63..a254e2c2d31 100644
--- a/gcc/testsuite/gcc.dg/pr118224.c
+++ b/gcc/testsuite/gcc.dg/pr118224.c
@@ -27,5 +27,7 @@ main ()
 #endif
   if (__builtin_calloc ((~(__SIZE_TYPE__) 0) / 2, 3))
     __builtin_abort ();
+  if (__builtin_calloc ((~(__SIZE_TYPE__) 0) / 16, 64))
+    __builtin_abort ();
   foo (1);
 }
diff --git a/gcc/tree-ssa-dce.cc b/gcc/tree-ssa-dce.cc
index 5b3037ac625..be21a2d0b50 100644
--- a/gcc/tree-ssa-dce.cc
+++ b/gcc/tree-ssa-dce.cc
@@ -331,7 +331,7 @@ is_removable_allocation_p (gcall *stmt, bool non_null_check)
 	return false;
       if (TREE_CODE (a1) == INTEGER_CST
 	  && TREE_CODE (a2) == INTEGER_CST
-	  && (wi::to_widest (a1) + wi::to_widest (a2)
+	  && (wi::to_widest (a1) * wi::to_widest (a2)
 	      > tree_to_uhwi (TYPE_MAX_VALUE (ptrdiff_type_node))))
 	return false;
       return true;