RFA: another patch to fix PR61360

Vladimir Makarov vmakarov@redhat.com
Tue Sep 23 01:26:00 GMT 2014


   The previous patch to solve PR61360 fixed the problem in IRA (it was 
easier for me to do as I know the code well)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61360

   Although imo it was an ok fix, Richard expressed concerns with the 
patch and the practice to have different enable attribute values 
depending on the current pass.

   I don't understand why "x,m" alternative is better to "x,r" and "x,r" 
should be disabled.  Even if the path from general regs to sse regs is 
slow (usually such slow path is implemented internally by 
micro-architecture through cache).  "x,r" alternative results in only 
smaller insns (including number of insns) with probably the same time 
for the movement.  So "x,r" should be at least no slower, insn cache 
should have more locality, and less overhead for decoding/translating insns.

   Here I propose another solution avoiding to have different enable 
attribute values.

   The patch was successfully bootstrapped on x86/x86-64 and tested with 
and without -march=amdfam10 (actually the patch results in 2 less 
failures when -march=amdfam10 were used).

   Uros, is i386.md change ok for the trunk?

2014-09-22  Vladimir Makarov  <vmakarov@redhat.com>

         PR target/61360
         * lra.c (lra): Remove call of recog_init.
         * config/i386/i386.md (*float<SWI48:mode><MODEF:mode>2_sse):
         Always enable first alternative.

-------------- next part --------------
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md	(revision 215337)
+++ config/i386/i386.md	(working copy)
@@ -4795,14 +4795,6 @@
               (symbol_ref "TARGET_MIX_SSE_I387
                            && X87_ENABLE_FLOAT (<MODEF:MODE>mode,
                                                 <SWI48:MODE>mode)")
-            (eq_attr "alternative" "1")
-              /* ??? For sched1 we need constrain_operands to be able to
-                 select an alternative.  Leave this enabled before RA.  */
-              (symbol_ref "TARGET_INTER_UNIT_CONVERSIONS
-                           || optimize_function_for_size_p (cfun)
-                           || !(reload_completed
-                                || reload_in_progress
-                                || lra_in_progress)")
            ]
            (symbol_ref "true")))
    ])
Index: lra.c
===================================================================
--- lra.c	(revision 215358)
+++ lra.c	(working copy)
@@ -2135,11 +2135,6 @@ lra (FILE *f)
 
   lra_in_progress = 1;
 
-  /* The enable attributes can change their values as LRA starts
-     although it is a bad practice.  To prevent reuse of the outdated
-     values, clear them.  */
-  recog_init ();
-
   lra_live_range_iter = lra_coalesce_iter = 0;
   lra_constraint_iter = lra_constraint_iter_after_spill = 0;
   lra_inheritance_iter = lra_undo_inheritance_iter = 0;


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