From: Siddhesh Poyarekar <siddhesh@gotplt.org>
Date: Tue, 17 Sep 2024 22:32:52 +0000 (-0400)
Subject: tree-object-size: use size_for_offset in more cases
X-Git-Tag: basepoints/gcc-16~5157
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=72ae35bbc90fea3bb0084187896b783c1451fd22;p=thirdparty%2Fgcc.git

tree-object-size: use size_for_offset in more cases

When wholesize != size, there is a reasonable opportunity for static
object sizes also to be computed using size_for_offset, so use that.

gcc/ChangeLog:

	* tree-object-size.cc (plus_stmt_object_size): Call
	SIZE_FOR_OFFSET for some negative offset cases.

gcc/testsuite/ChangeLog:

	* gcc.dg/builtin-object-size-3.c (test9): Adjust test.
	* gcc.dg/builtin-object-size-4.c (test8): Likewise.

Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
---

diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-3.c b/gcc/testsuite/gcc.dg/builtin-object-size-3.c
index 3f58da3d500..ec2c62c9640 100644
--- a/gcc/testsuite/gcc.dg/builtin-object-size-3.c
+++ b/gcc/testsuite/gcc.dg/builtin-object-size-3.c
@@ -574,7 +574,7 @@ test9 (unsigned cond)
   if (__builtin_object_size (&p[-4], 2) != (cond ? 6 : 10))
     FAIL ();
 #else
-  if (__builtin_object_size (&p[-4], 2) != 0)
+  if (__builtin_object_size (&p[-4], 2) != 6)
     FAIL ();
 #endif
 
@@ -585,7 +585,7 @@ test9 (unsigned cond)
   if (__builtin_object_size (p, 2) != ((cond ? 2 : 6) + cond))
     FAIL ();
 #else
-  if (__builtin_object_size (p, 2) != 0)
+  if (__builtin_object_size (p, 2) != 2)
     FAIL ();
 #endif
 
@@ -598,7 +598,7 @@ test9 (unsigned cond)
       != sizeof (y) - __builtin_offsetof (struct A, c) - 8 + cond)
     FAIL ();
 #else
-  if (__builtin_object_size (p, 2) != 0)
+  if (__builtin_object_size (p, 2) != sizeof (y) - __builtin_offsetof (struct A, c) - 8)
     FAIL ();
 #endif
 }
diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-4.c b/gcc/testsuite/gcc.dg/builtin-object-size-4.c
index b3eb36efb74..7bcd24c4150 100644
--- a/gcc/testsuite/gcc.dg/builtin-object-size-4.c
+++ b/gcc/testsuite/gcc.dg/builtin-object-size-4.c
@@ -482,7 +482,7 @@ test8 (unsigned cond)
   if (__builtin_object_size (&p[-4], 3) != (cond ? 6 : 10))
     FAIL ();
 #else
-  if (__builtin_object_size (&p[-4], 3) != 0)
+  if (__builtin_object_size (&p[-4], 3) != 6)
     FAIL ();
 #endif
 
@@ -493,7 +493,7 @@ test8 (unsigned cond)
   if (__builtin_object_size (p, 3) != ((cond ? 2 : 6) + cond))
     FAIL ();
 #else
-  if (__builtin_object_size (p, 3) != 0)
+  if (__builtin_object_size (p, 3) != 2)
     FAIL ();
 #endif
 
@@ -505,7 +505,7 @@ test8 (unsigned cond)
   if (__builtin_object_size (p, 3) != sizeof (y.c) - 8 + cond)
     FAIL ();
 #else
-  if (__builtin_object_size (p, 3) != 0)
+  if (__builtin_object_size (p, 3) != sizeof (y.c) - 8)
     FAIL ();
 #endif
 }
diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
index 6544730e153..78faae7ad0d 100644
--- a/gcc/tree-object-size.cc
+++ b/gcc/tree-object-size.cc
@@ -1527,6 +1527,7 @@ plus_stmt_object_size (struct object_size_info *osi, tree var, gimple *stmt)
       if (size_unknown_p (bytes, 0))
 	;
       else if ((object_size_type & OST_DYNAMIC)
+	       || bytes != wholesize
 	       || compare_tree_int (op1, offset_limit) <= 0)
 	bytes = size_for_offset (bytes, op1, wholesize);
       /* In the static case, with a negative offset, the best estimate for