From 879f0ee122477e2b08b7cabea104338d9a9198eb Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Mon, 9 Dec 2024 23:11:25 +0000
Subject: [PATCH] malloc: add indirection for malloc(-like) functions in
 tests [BZ #32366]

GCC 15 introduces allocation dead code removal (DCE) for PR117370 in
r15-5255-g7828dc070510f8. This breaks various glibc tests which want
to assert various properties of the allocator without doing anything
obviously useful with the allocated memory.

Alexander Monakov rightly pointed out that we can and should do better
than passing -fno-malloc-dce to paper over the problem. Not least because
GCC 14 already does such DCE where there's no testing of malloc's return
value against NULL, and LLVM has such optimisations too.

Handle this by providing malloc (and friends) wrappers with a volatile
function pointer to obscure that we're calling malloc (et. al) from the
compiler.

Reviewed-by: Paul Eggert <eggert@cs.ucla.edu>
(cherry picked from commit a9944a52c967ce76a5894c30d0274b824df43c7a)
---
 malloc/tst-aligned-alloc.c    |  2 ++
 malloc/tst-compathooks-off.c  |  2 ++
 malloc/tst-malloc-aux.h       | 41 +++++++++++++++++++++++++++++++++++
 malloc/tst-malloc-check.c     |  2 ++
 malloc/tst-malloc-too-large.c |  1 +
 malloc/tst-malloc.c           |  2 ++
 malloc/tst-realloc.c          |  2 ++
 support/support.h             |  2 +-
 test-skeleton.c               |  1 -
 9 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 malloc/tst-malloc-aux.h

diff --git a/malloc/tst-aligned-alloc.c b/malloc/tst-aligned-alloc.c
index 8bd6527147..39f0cd22c0 100644
--- a/malloc/tst-aligned-alloc.c
+++ b/malloc/tst-aligned-alloc.c
@@ -25,6 +25,8 @@
 #include <libc-diag.h>
 #include <support/check.h>
 
+#include "tst-malloc-aux.h"
+
 static int
 do_test (void)
 {
diff --git a/malloc/tst-compathooks-off.c b/malloc/tst-compathooks-off.c
index 134d7ea107..cd8043d6f5 100644
--- a/malloc/tst-compathooks-off.c
+++ b/malloc/tst-compathooks-off.c
@@ -25,6 +25,8 @@
 #include <support/check.h>
 #include <support/support.h>
 
+#include "tst-malloc-aux.h"
+
 extern void (*volatile __free_hook) (void *, const void *);
 extern void *(*volatile __malloc_hook)(size_t, const void *);
 extern void *(*volatile __realloc_hook)(void *, size_t, const void *);
diff --git a/malloc/tst-malloc-aux.h b/malloc/tst-malloc-aux.h
new file mode 100644
index 0000000000..54908b4a24
--- /dev/null
+++ b/malloc/tst-malloc-aux.h
@@ -0,0 +1,41 @@
+/* Wrappers for malloc-like functions to allow testing the implementation
+   without optimization.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef TST_MALLOC_AUX_H
+#define TST_MALLOC_AUX_H
+
+#include <stddef.h>
+#include <stdlib.h>
+
+static void *(*volatile aligned_alloc_indirect)(size_t, size_t) = aligned_alloc;
+static void *(*volatile calloc_indirect)(size_t, size_t) = calloc;
+static void *(*volatile malloc_indirect)(size_t) = malloc;
+static void *(*volatile realloc_indirect)(void*, size_t) = realloc;
+
+#undef aligned_alloc
+#undef calloc
+#undef malloc
+#undef realloc
+
+#define aligned_alloc aligned_alloc_indirect
+#define calloc calloc_indirect
+#define malloc malloc_indirect
+#define realloc realloc_indirect
+
+#endif /* TST_MALLOC_AUX_H */
diff --git a/malloc/tst-malloc-check.c b/malloc/tst-malloc-check.c
index df9fd67c13..18c6f28f80 100644
--- a/malloc/tst-malloc-check.c
+++ b/malloc/tst-malloc-check.c
@@ -20,6 +20,8 @@
 #include <stdlib.h>
 #include <libc-diag.h>
 
+#include "tst-malloc-aux.h"
+
 static int errors = 0;
 
 static void
diff --git a/malloc/tst-malloc-too-large.c b/malloc/tst-malloc-too-large.c
index 5be6800b89..44979018b8 100644
--- a/malloc/tst-malloc-too-large.c
+++ b/malloc/tst-malloc-too-large.c
@@ -43,6 +43,7 @@
 #include <unistd.h>
 #include <sys/param.h>
 
+#include "tst-malloc-aux.h"
 
 /* This function prepares for each 'too-large memory allocation' test by
    performing a small successful malloc/free and resetting errno prior to
diff --git a/malloc/tst-malloc.c b/malloc/tst-malloc.c
index 0da5a8f263..7b337e6e09 100644
--- a/malloc/tst-malloc.c
+++ b/malloc/tst-malloc.c
@@ -20,6 +20,8 @@
 #include <stdio.h>
 #include <libc-diag.h>
 
+#include "tst-malloc-aux.h"
+
 static int errors = 0;
 
 static void
diff --git a/malloc/tst-realloc.c b/malloc/tst-realloc.c
index fb661d312e..b35a5a2125 100644
--- a/malloc/tst-realloc.c
+++ b/malloc/tst-realloc.c
@@ -23,6 +23,8 @@
 #include <libc-diag.h>
 #include <support/check.h>
 
+#include "tst-malloc-aux.h"
+
 static int
 do_test (void)
 {
diff --git a/support/support.h b/support/support.h
index b7f76bf080..3742f26b55 100644
--- a/support/support.h
+++ b/support/support.h
@@ -113,7 +113,7 @@ void *xposix_memalign (size_t alignment, size_t n)
   __attribute_malloc__ __attribute_alloc_align__ ((1))
   __attribute_alloc_size__ ((2)) __attr_dealloc_free __returns_nonnull;
 char *xasprintf (const char *format, ...)
-  __attribute__ ((format (printf, 1, 2), malloc)) __attr_dealloc_free
+  __attribute__ ((format (printf, 1, 2), __malloc__)) __attr_dealloc_free
   __returns_nonnull;
 char *xstrdup (const char *) __attr_dealloc_free __returns_nonnull;
 char *xstrndup (const char *, size_t) __attr_dealloc_free __returns_nonnull;
diff --git a/test-skeleton.c b/test-skeleton.c
index efd52a6fa4..508522fa33 100644
--- a/test-skeleton.c
+++ b/test-skeleton.c
@@ -27,7 +27,6 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <getopt.h>
-#include <malloc.h>
 #include <paths.h>
 #include <search.h>
 #include <signal.h>
-- 
2.27.0