[PATCH] Make disabled-optimization warning more informative; increase default max-gcse-memory

	* gcc/cprop.c (is_too_expensive): Remove.
	(gcse.h): Include.
	(one_cprop_pass): Call gcse_or_cprop_is_too_expensive, not
	is_too_expensive.
	* gcc/gcse.h (gcse_or_cprop_is_too_expensive): Declare.
	* gcc/gcse.c (is_too_expensive): Rename to ...
	(gcse_or_cprop_is_too_expensive): ... this.
	Expand warning to add required size of max-gcse-memory.
	(one_pre_gcse_pass): Use it.
	(one_code_hoisting_pass): Use it.
 	* gcc/params.def (max-gcse-memory): Increase from 50MB to 128MB.

From-SVN: r230276

5 files changed, 30 insertions, 53 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5093ce0..1d8da27 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2015-11-12  Brad Lucier  <lucier@math.purdue.edu>
+
+	* gcc/cprop.c (is_too_expensive): Remove.
+	(gcse.h): Include.
+	(one_cprop_pass): Call gcse_or_cprop_is_too_expensive, not
+	is_too_expensive.
+	* gcc/gcse.h (gcse_or_cprop_is_too_expensive): Declare.
+	* gcc/gcse.c (is_too_expensive): Rename to ...
+	(gcse_or_cprop_is_too_expensive): ... this.
+	Expand warning to add required size of max-gcse-memory.
+	(one_pre_gcse_pass): Use it.
+	(one_code_hoisting_pass): Use it.
+ 	* gcc/params.def (max-gcse-memory): Increase from 50MB to 128MB.
+
 2015-11-12  James Norris  <jnorris@codesourcery.com>
 	    Joseph Myers  <joseph@codesourcery.com>
 
diff --git a/gcc/cprop.c b/gcc/cprop.c
index 082f9fd..7f1acc0 100644
--- a/gcc/cprop.c
+++ b/gcc/cprop.c
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "dbgcnt.h"
 #include "cfgloop.h"
+#include "gcse.h"
 
 
 /* An obstack for our working variables.  */
@@ -1724,47 +1725,6 @@ bypass_conditional_jumps (void)
   return changed;
 }
 
-/* Return true if the graph is too expensive to optimize.  PASS is the
-   optimization about to be performed.  */
-
-static bool
-is_too_expensive (const char *pass)
-{
-  /* Trying to perform global optimizations on flow graphs which have
-     a high connectivity will take a long time and is unlikely to be
-     particularly useful.
-
-     In normal circumstances a cfg should have about twice as many
-     edges as blocks.  But we do not want to punish small functions
-     which have a couple switch statements.  Rather than simply
-     threshold the number of blocks, uses something with a more
-     graceful degradation.  */
-  if (n_edges_for_fn (cfun) > 20000 + n_basic_blocks_for_fn (cfun) * 4)
-    {
-      warning (OPT_Wdisabled_optimization,
-	       "%s: %d basic blocks and %d edges/basic block",
-	       pass, n_basic_blocks_for_fn (cfun),
-	       n_edges_for_fn (cfun) / n_basic_blocks_for_fn (cfun));
-
-      return true;
-    }
-
-  /* If allocating memory for the cprop bitmap would take up too much
-     storage it's better just to disable the optimization.  */
-  if ((n_basic_blocks_for_fn (cfun)
-       * SBITMAP_SET_SIZE (max_reg_num ())
-       * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
-    {
-      warning (OPT_Wdisabled_optimization,
-	       "%s: %d basic blocks and %d registers",
-	       pass, n_basic_blocks_for_fn (cfun), max_reg_num ());
-
-      return true;
-    }
-
-  return false;
-}
-
 /* Main function for the CPROP pass.  */
 
 static int
@@ -1775,7 +1735,7 @@ one_cprop_pass (void)
 
   /* Return if there's nothing to do, or it is too expensive.  */
   if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1
-      || is_too_expensive (_ ("const/copy propagation disabled")))
+      || gcse_or_cprop_is_too_expensive (_ ("const/copy propagation disabled")))
     return 0;
 
   global_const_prop_count = local_const_prop_count = 0;
diff --git a/gcc/gcse.c b/gcc/gcse.c
index dcee396..64f04c7 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -510,7 +510,6 @@ static void trim_ld_motion_mems (void);
 static void update_ld_motion_stores (struct gcse_expr *);
 static void clear_modify_mem_tables (void);
 static void free_modify_mem_tables (void);
-static bool is_too_expensive (const char *);
 
 #define GNEW(T)			((T *) gmalloc (sizeof (T)))
 #define GCNEW(T)		((T *) gcalloc (1, sizeof (T)))
@@ -2565,7 +2564,7 @@ one_pre_gcse_pass (void)
 
   /* Return if there's nothing to do, or it is too expensive.  */
   if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1
-      || is_too_expensive (_("PRE disabled")))
+      || gcse_or_cprop_is_too_expensive (_("PRE disabled")))
     return 0;
 
   /* We need alias.  */
@@ -3493,7 +3492,7 @@ one_code_hoisting_pass (void)
 
   /* Return if there's nothing to do, or it is too expensive.  */
   if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1
-      || is_too_expensive (_("GCSE disabled")))
+      || gcse_or_cprop_is_too_expensive (_("GCSE disabled")))
     return 0;
 
   doing_code_hoisting_p = true;
@@ -3957,9 +3956,13 @@ update_ld_motion_stores (struct gcse_expr * expr)
 /* Return true if the graph is too expensive to optimize. PASS is the
    optimization about to be performed.  */
 
-static bool
-is_too_expensive (const char *pass)
+bool
+gcse_or_cprop_is_too_expensive (const char *pass)
 {
+  unsigned int memory_request = (n_basic_blocks_for_fn (cfun)
+				 * SBITMAP_SET_SIZE (max_reg_num ())
+				 * sizeof (SBITMAP_ELT_TYPE));
+  
   /* Trying to perform global optimizations on flow graphs which have
      a high connectivity will take a long time and is unlikely to be
      particularly useful.
@@ -3981,13 +3984,12 @@ is_too_expensive (const char *pass)
 
   /* If allocating memory for the dataflow bitmaps would take up too much
      storage it's better just to disable the optimization.  */
-  if ((n_basic_blocks_for_fn (cfun)
-       * SBITMAP_SET_SIZE (max_reg_num ())
-       * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
+  if (memory_request > MAX_GCSE_MEMORY)
     {
       warning (OPT_Wdisabled_optimization,
-	       "%s: %d basic blocks and %d registers",
-	       pass, n_basic_blocks_for_fn (cfun), max_reg_num ());
+	       "%s: %d basic blocks and %d registers; increase --param max-gcse-memory above %d",
+	       pass, n_basic_blocks_for_fn (cfun), max_reg_num (),
+	       memory_request);
 
       return true;
     }
diff --git a/gcc/gcse.h b/gcc/gcse.h
index e28a07d..7528153 100644
--- a/gcc/gcse.h
+++ b/gcc/gcse.h
@@ -40,5 +40,6 @@ extern struct target_gcse *this_target_gcse;
 #endif
 
 void gcse_c_finalize (void);
+extern bool gcse_or_cprop_is_too_expensive (const char *);
 
 #endif
diff --git a/gcc/params.def b/gcc/params.def
index c5d96e7..41fd8a8 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -218,7 +218,7 @@ DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 	 "max-gcse-memory",
 	 "The maximum amount of memory to be allocated by GCSE.",
-	 50 * 1024 * 1024, 0, 0)
+	 128 * 1024 * 1024, 0, 0)
 
 /* The GCSE optimization of an expression will avoided if the ratio of
    insertions to deletions is greater than this value.  */