Re: [Ada] Fix wrong code for loops with convoluted control flow

[Eric Botcazou]

> Tested on x86_64-suse-linux, applied on the mainline, 8 and 7 branches.
> 
> 
> 2018-11-08  Eric Botcazou  <ebotca...@adacore.com>
> 
>       * fe.h (Suppress_Checks): Declare.
>       * gcc-interface/misc.c (gnat_init_gcc_eh): Set -fnon-call-exceptions
>       only if checks are not suppressed and -faggressive-loop-optimizations
>       only if they are.
>       * gcc-interface/trans.c (struct loop_info_d): Remove has_checks and
>       warned_aggressive_loop_optimizations fields.
>       (gigi): Do not clear warn_aggressive_loop_optimizations here.
>       (Raise_Error_to_gnu): Do not set has_checks.
>       (gnat_to_gnu) <N_Indexed_Component>: Remove support for aggressive
>       loop optimizations.

The following small adjustment is needed on some platforms.  Applied.


        * gcc-interface/misc.c (gnat_init_gcc_eh): Set -fnon-call-exceptions
        for the runtime on platforms where System.Machine_Overflow is true.

-- 
Eric Botcazou
Index: gcc-interface/misc.c
===================================================================
--- gcc-interface/misc.c	(revision 266029)
+++ gcc-interface/misc.c	(working copy)
@@ -405,10 +405,15 @@ gnat_init_gcc_eh (void)
      as permitted in Ada.
      Turn off -faggressive-loop-optimizations because it may optimize away
      out-of-bound array accesses that we want to be able to catch.
-     If checks are disabled, we use the same settings as the C++ compiler.  */
+     If checks are disabled, we use the same settings as the C++ compiler,
+     except for the runtime on platforms where S'Machine_Overflow is true
+     because the runtime depends on FP (hardware) checks being properly
+     handled despite being compiled in -gnatp mode.  */
   flag_exceptions = 1;
   flag_delete_dead_exceptions = 1;
-  if (!Suppress_Checks)
+  if (Suppress_Checks)
+    flag_non_call_exceptions = Machine_Overflows_On_Target && GNAT_Mode;
+  else
     {
       flag_non_call_exceptions = 1;
       flag_aggressive_loop_optimizations = 0;