[glibc/release/2.40/master] malloc: obscure calloc use in tst-calloc

[Sam James]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=be48b8f6ad0ec6d0d6b1d2f45eb59bf8e8c67dd7

commit be48b8f6ad0ec6d0d6b1d2f45eb59bf8e8c67dd7
Author: Sam James <sam@gentoo.org>
Date:   Fri Jan 10 03:03:47 2025 +0000

    malloc: obscure calloc use in tst-calloc
    
    Similar to a9944a52c967ce76a5894c30d0274b824df43c7a and
    f9493a15ea9cfb63a815c00c23142369ec09d8ce, we need to hide calloc use from
    the compiler to accommodate GCC's r15-6566-g804e9d55d9e54c change.
    
    First, include tst-malloc-aux.h, but then use `volatile` variables
    for size.
    
    The test passes without the tst-malloc-aux.h change but IMO we want
    it there for consistency and to avoid future problems (possibly silent).
    
    Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
    (cherry picked from commit c3d1dac96bdd10250aa37bb367d5ef8334a093a1)

Diff:
---
 malloc/tst-calloc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/malloc/tst-calloc.c b/malloc/tst-calloc.c
index 01f17f9e65..5a8c7ab121 100644
--- a/malloc/tst-calloc.c
+++ b/malloc/tst-calloc.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <libc-diag.h>
 
+#include "tst-malloc-aux.h"
 
 /* Number of samples per size.  */
 #define N 50000
@@ -94,16 +95,19 @@ random_test (void)
 static void
 null_test (void)
 {
+  /* Obscure allocation size from the compiler.  */
+  volatile size_t max_size = UINT_MAX;
+  volatile size_t zero_size = 0;
   /* If the size is 0 the result is implementation defined.  Just make
      sure the program doesn't crash.  The result of calloc is
      deliberately ignored, so do not warn about that.  */
   DIAG_PUSH_NEEDS_COMMENT;
   DIAG_IGNORE_NEEDS_COMMENT (10, "-Wunused-result");
   calloc (0, 0);
-  calloc (0, UINT_MAX);
-  calloc (UINT_MAX, 0);
-  calloc (0, ~((size_t) 0));
-  calloc (~((size_t) 0), 0);
+  calloc (0, max_size);
+  calloc (max_size, 0);
+  calloc (0, ~((size_t) zero_size));
+  calloc (~((size_t) zero_size), 0);
   DIAG_POP_NEEDS_COMMENT;
 }