[COMMITTED] ada: Adjust comments in targparm.ads

["Marc Poulhiès" <poulhies@adacore.com>]

From: Ronan Desplanques <desplanques@adacore.com>

This patch removes a few dangling references to the late front-end
implementation of exceptions from the comments of targparm.ads, and
also fixes a thinko there.

gcc/ada/

	* targparm.ads: Remove references to front-end-based exceptions. Fix
	thinko.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/targparm.ads | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/gcc/ada/targparm.ads b/gcc/ada/targparm.ads
index aa91ee60e82..01ee492e015 100644
--- a/gcc/ada/targparm.ads
+++ b/gcc/ada/targparm.ads
@@ -213,22 +213,7 @@ package Targparm is
    -- Control of Exception Handling --
    -----------------------------------
 
-   --  GNAT implements three methods of implementing exceptions:
-
-   --    Front-End Longjmp/Setjmp Exceptions
-
-   --      This approach uses longjmp/setjmp to handle exceptions. It
-   --      uses less storage, and can often propagate exceptions faster,
-   --      at the expense of (sometimes considerable) overhead in setting
-   --      up an exception handler.
-
-   --      The generation of the setjmp and longjmp calls is handled by
-   --      the front end of the compiler (this includes gigi in the case
-   --      of the standard GCC back end). It does not use any back end
-   --      support (such as the GCC3 exception handling mechanism). When
-   --      this approach is used, the compiler generates special exception
-   --      handlers for handling cleanups (AT-END actions) when an exception
-   --      is raised.
+   --  GNAT provides two methods of implementing exceptions:
 
    --    Back-End Zero Cost Exceptions
 
@@ -254,10 +239,10 @@ package Targparm is
 
    --    Control of Available Methods and Defaults
 
-   --      The following switches specify whether we're using a front-end or a
-   --      back-end mechanism and whether this is a zero-cost or a sjlj scheme.
+   --      The following switch specifies whether this is a zero-cost or a sjlj
+   --      scheme.
 
-   --      The per-switch default values correspond to the default value of
+   --      The default value corresponds to the default value of
    --      Opt.Exception_Mechanism.
 
    ZCX_By_Default_On_Target : Boolean := False;
@@ -408,7 +393,7 @@ package Targparm is
    -- Control of Stack Checking --
    -------------------------------
 
-   --  GNAT provides three methods of implementing exceptions:
+   --  GNAT provides three methods of implementing stack checking:
 
    --    GCC Probing Mechanism
 
-- 
2.40.0