Add the --disable-initial-exec-tls configure option.
Right now we always make our TLS use the initial-exec model if the compiler
supports it. This change allows configure-time disabling of this setting, which
can be helpful when dynamically loading jemalloc is the only option.
diff --git a/INSTALL.md b/INSTALL.md
index dff7ceb..082310f 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -265,6 +265,15 @@
configuration, jemalloc will provide additional size classes that are not
16-byte-aligned (24, 40, and 56).
+* `--disable-initial-exec-tls`
+
+ Disable the initial-exec TLS model for jemalloc's internal thread-local
+ storage (on those platforms that support explicit settings). This can allow
+ jemalloc to be dynamically loaded after program starup (e.g. using dlopen).
+ Note that in this case, there will be two malloc implementations operating
+ in the same process, which will almost certainly result in confusing runtime
+ crashes if pointers leak from one implementation to the other.
+
The following environment variables (not a definitive list) impact configure's
behavior:
diff --git a/configure.ac b/configure.ac
index e45970e..ba0b694 100644
--- a/configure.ac
+++ b/configure.ac
@@ -733,12 +733,9 @@
foo = 0;],
[je_cv_tls_model])
JE_CFLAGS_RESTORE()
-if test "x${je_cv_tls_model}" = "xyes" ; then
- AC_DEFINE([JEMALLOC_TLS_MODEL],
- [__attribute__((tls_model("initial-exec")))])
-else
- AC_DEFINE([JEMALLOC_TLS_MODEL], [ ])
-fi
+dnl (Setting of JEMALLOC_TLS_MODEL is done later, after we've checked for
+dnl --disable-initial-exec-tls)
+
dnl Check for alloc_size attribute support.
JE_CFLAGS_SAVE()
JE_CFLAGS_ADD([-Werror])
@@ -1994,6 +1991,29 @@
fi
dnl ============================================================================
+dnl Use initial-exec TLS by default.
+AC_ARG_ENABLE([initial-exec-tls],
+ [AS_HELP_STRING([--disable-initial-exec-tls],
+ [Disable the initial-exec tls model])],
+[if test "x$enable_initial_exec_tls" = "xno" ; then
+ enable_initial_exec_tls="0"
+else
+ enable_initial_exec_tls="1"
+fi
+],
+[enable_initial_exec_tls="1"]
+)
+AC_SUBST([enable_initial_exec_tls])
+
+if test "x${je_cv_tls_model}" = "xyes" -a \
+ "x${enable_initial_exec_tls}" = "x1" ; then
+ AC_DEFINE([JEMALLOC_TLS_MODEL],
+ [__attribute__((tls_model("initial-exec")))])
+else
+ AC_DEFINE([JEMALLOC_TLS_MODEL], [ ])
+fi
+
+dnl ============================================================================
dnl Enable background threads if possible.
if test "x${have_pthread}" = "x1" -a "x${have_dlsym}" = "x1" \
