Protect __TMC_END__ - __TMC_LIST__ == 0

2016-11-20  Marc Glisse  <marc.glisse@inria.fr>

        PR libgcc/77813
        * crtstuff.c (deregister_tm_clones, register_tm_clones): Hide
        __TMC_END__ behind a passthrough asm.

From-SVN: r242635

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 6f985239dffb7fbfedc1368e59a6acc9d6d89c52..90d7ee8d0795a8ab96c28eadbedf917f144d585f 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,6 +1,12 @@
+2016-11-20  Marc Glisse  <marc.glisse@inria.fr>
+
+       PR libgcc/77813
+       * crtstuff.c (deregister_tm_clones, register_tm_clones): Hide
+       __TMC_END__ behind a passthrough asm.
+
 2016-11-18  Walter Lee  <walt@tilera.com>
 
-        * config.host (tilepro*-*-linux*): Add t-slibgcc-libgcc to tmake_file.
+       * config.host (tilepro*-*-linux*): Add t-slibgcc-libgcc to tmake_file.
 
 2016-11-17  Andrew Senkevich <andrew.senkevich@intel.com>
 

diff --git a/libgcc/crtstuff.c b/libgcc/crtstuff.c
index 5449c4dbdb638ac68d94c3a0202f2d3b2e6b0a49..564418191d9698a694275d0f42c9ecbc07719d36 100644 (file)
--- a/libgcc/crtstuff.c
+++ b/libgcc/crtstuff.c
@@ -280,7 +280,10 @@ deregister_tm_clones (void)
   void (*fn) (void *);
 
 #ifdef HAVE_GAS_HIDDEN
-  if (__TMC_END__ - __TMC_LIST__ == 0)
+  func_ptr *end = __TMC_END__;
+  // Do not optimize the comparison to false.
+  __asm ("" : "+g" (end));
+  if (__TMC_LIST__ == end)
     return;
 #else
   if (__TMC_LIST__[0] == NULL)
@@ -300,7 +303,10 @@ register_tm_clones (void)
   size_t size;
 
 #ifdef HAVE_GAS_HIDDEN
-  size = (__TMC_END__ - __TMC_LIST__) / 2;
+  func_ptr *end = __TMC_END__;
+  // Do not optimize the comparison to false.
+  __asm ("" : "+g" (end));
+  size = (end - __TMC_LIST__) / 2;
 #else
   for (size = 0; __TMC_LIST__[size * 2] != NULL; size++)
     continue;