Remove --disable-experimental-malloc option

It is the default since 2.26 and it has bitrotten over the years,
By using it multiple malloc tests fails:

  FAIL: malloc/tst-memalign-2
  FAIL: malloc/tst-memalign-2-malloc-hugetlb1
  FAIL: malloc/tst-memalign-2-malloc-hugetlb2
  FAIL: malloc/tst-memalign-2-mcheck
  FAIL: malloc/tst-mxfast-malloc-hugetlb1
  FAIL: malloc/tst-mxfast-malloc-hugetlb2
  FAIL: malloc/tst-tcfree2
  FAIL: malloc/tst-tcfree2-malloc-hugetlb1
  FAIL: malloc/tst-tcfree2-malloc-hugetlb2

Checked on x86_64-linux-gnu.

Reviewed-by: DJ Delorie <dj@redhat.com>

INSTALL

@@ -258,12 +258,6 @@ if 'CFLAGS' is specified it must enable optimization.  For example:
      independently-maintained implementations of libcrypt.  It may
      become the default in a future release.
 
-'--disable-experimental-malloc'
-     By default, a per-thread cache is enabled in 'malloc'.  While this
-     cache can be disabled on a per-application basis using tunables
-     (set glibc.malloc.tcache_count to zero), this option can be used to
-     remove it from the build completely.
-
 '--disable-scv'
      Disable using 'scv' instruction for syscalls.  All syscalls will
      use 'sc' instead, even if the kernel supports 'scv'.  PowerPC only.

NEWS

@@ -30,6 +30,10 @@ Deprecated and removed features, and other changes affecting compatibility:
   alternatively stable kernels from versions 6.1.6, 5.15.87, 5.10.163,
   5.4.228, 4.19.270 or 4.14.303.
 
+* The --disable-experimental-malloc is no longer available.  The per-thread
+  cache can still be disable per-application using tunables
+  (glibc.malloc.tcache_count set to zero).
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]

config.make.in

@@ -77,8 +77,6 @@ multi-arch = @multi_arch@
 
 mach-interface-list = @mach_interface_list@
 
-experimental-malloc = @experimental_malloc@
-
 memory-tagging = @memory_tagging@
 
 nss-crypt = @libc_cv_nss_crypt@

configure

@@ -671,7 +671,6 @@ libc_cv_static_nss_crypt
 libc_cv_nss_crypt
 build_crypt
 memory_tagging
-experimental_malloc
 enable_werror
 all_warnings
 force_install
@@ -774,7 +773,6 @@ enable_kernel
 enable_all_warnings
 enable_werror
 enable_multi_arch
-enable_experimental_malloc
 enable_memory_tagging
 enable_crypt
 enable_nss_crypt
@@ -1441,8 +1439,6 @@ Optional Features:
   --disable-werror        do not build with -Werror
   --enable-multi-arch     enable single DSO with optimizations for multiple
                           architectures
-  --disable-experimental-malloc
-                          disable experimental malloc features
   --enable-memory-tagging enable memory tagging if supported by the
                           architecture [default=no]
   --disable-crypt         do not build nor install the passphrase hashing
@@ -3455,15 +3451,6 @@ else
 fi
 
 
-# Check whether --enable-experimental-malloc was given.
-if test "${enable_experimental_malloc+set}" = set; then :
-  enableval=$enable_experimental_malloc; experimental_malloc=$enableval
-else
-  experimental_malloc=yes
-fi
-
-
-
 # Check whether --enable-memory-tagging was given.
 if test "${enable_memory_tagging+set}" = set; then :
   enableval=$enable_memory_tagging; memory_tagging=$enableval

configure.ac

@@ -300,13 +300,6 @@ AC_ARG_ENABLE([multi-arch],
 	      [multi_arch=$enableval],
 	      [multi_arch=default])
 
-AC_ARG_ENABLE([experimental-malloc],
-	      AS_HELP_STRING([--disable-experimental-malloc],
-			     [disable experimental malloc features]),
-	      [experimental_malloc=$enableval],
-	      [experimental_malloc=yes])
-AC_SUBST(experimental_malloc)
-
 AC_ARG_ENABLE([memory-tagging],
 	      AS_HELP_STRING([--enable-memory-tagging],
 			     [enable memory tagging if supported by the architecture @<:@default=no@:>@]),

malloc/Makefile

@@ -286,11 +286,7 @@ tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3 \
 tst-mxfast-ENV = GLIBC_TUNABLES=glibc.malloc.tcache_count=0:glibc.malloc.mxfast=0
 
 CPPFLAGS-malloc-debug.c += -DUSE_TCACHE=0
-ifeq ($(experimental-malloc),yes)
 CPPFLAGS-malloc.c += -DUSE_TCACHE=1
-else
-CPPFLAGS-malloc.c += -DUSE_TCACHE=0
-endif
 # Uncomment this for test releases.  For public releases it is too expensive.
 #CPPFLAGS-malloc.o += -DMALLOC_DEBUG=1
 

manual/install.texi

@@ -286,12 +286,6 @@ This option is for hackers and distributions experimenting with
 independently-maintained implementations of libcrypt.  It may become
 the default in a future release.
 
-@item --disable-experimental-malloc
-By default, a per-thread cache is enabled in @code{malloc}.  While
-this cache can be disabled on a per-application basis using tunables
-(set glibc.malloc.tcache_count to zero), this option can be used to
-remove it from the build completely.
-
 @item --disable-scv
 Disable using @code{scv} instruction for syscalls. All syscalls will use
 @code{sc} instead, even if the kernel supports @code{scv}. PowerPC only.

scripts/build-many-glibcs.py

@@ -447,7 +447,6 @@ class Context(object):
                                                '--disable-mathvec',
                                                '--disable-tunables',
                                                '--disable-crypt',
-                                               '--disable-experimental-malloc',
                                                '--disable-build-nscd',
                                                '--disable-nscd']},
                                       {'variant': 'no-pie',