params.def (PARAM_SRA_MAX_STRUCTURE_SIZE): New.

	* params.def (PARAM_SRA_MAX_STRUCTURE_SIZE): New.
	(PARAM_SRA_FIELD_STRUCTURE_RATIO): Likewise.
	* params.h (SRA_MAX_STRUCTURE_SIZE): New.
	(SRA_FIELD_STRUCTURE_RATIO): Likewise.
	* tree-sra.c: Include "params.h".
	(decide_block_copy): Use new parameters.
	* doc/invoke.texi (Optimize Options): Document new SRA pass
	parameters sra-max-structure-size and sra-field-structure-ratio.

[testsuite]
	* gcc.dg/tree-ssa/sra-1.c: Pass --param sra-max-structure-size.

From-SVN: r89711

7 files changed, 63 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 898e2e9..8d19733 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2004-10-28  Ben Elliston  <bje@au.ibm.com>
+
+	* params.def (PARAM_SRA_MAX_STRUCTURE_SIZE): New.
+	(PARAM_SRA_FIELD_STRUCTURE_RATIO): Likewise.
+	* params.h (SRA_MAX_STRUCTURE_SIZE): New.
+	(SRA_FIELD_STRUCTURE_RATIO): Likewise.
+	* tree-sra.c: Include "params.h".
+	(decide_block_copy): Use new parameters.
+	* doc/invoke.texi (Optimize Options): Document new SRA pass
+	parameters sra-max-structure-size and sra-field-structure-ratio.
+
 2004-10-27  Nicolas Pitre <nico@cam.org>
 
 	* config/arm/ieee754-df.S (floatdidf): Fix regression with big values.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 990b83c..ceeae22 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -5313,6 +5313,19 @@ In each case, the @var{value} is an integer.  The allowable choices for
 @var{name} are given in the following table:
 
 @table @gcctabopt
+@item sra-max-structure-size
+The maximum structure size, in bytes, at which the scalar replacement
+of aggregates (SRA) optimization will perform block copies.  The
+default value, 0, implies that GCC will select the most appropriate
+size itself.
+
+@item sra-field-structure-ratio
+The treshold ratio (as a percentage) between instantiated fields and
+the complete structure size.  We say that if the ratio of the number
+of bytes in instantiated fields to the number of bytes in the complete
+structure exceeds this parameter, then block copies are not used.  The
+default is 75.
+
 @item max-crossjump-edges
 The maximum number of incoming edges to consider for crossjumping.
 The algorithm used by @option{-fcrossjumping} is @math{O(N^2)} in
diff --git a/gcc/params.def b/gcc/params.def
index 79c55bc..5bde4a1 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -35,6 +35,25 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 
    Be sure to add an entry to invoke.texi summarizing the parameter.  */
 
+/* The maximum structure size at which the scalar replacement of
+   aggregates (SRA) pass will perform block copies.  The default
+   value, 0, implies that GCC will select the most appropriate size
+   itself.  */
+DEFPARAM (PARAM_SRA_MAX_STRUCTURE_SIZE,
+	  "sra-max-structure-size",
+	  "The maximum structure size (in bytes) at which GCC will do block copies.",
+	  0)
+
+/* The ratio between instantiated fields and the complete structure
+   size.  We say that if the ratio of the number of bytes in
+   instantiated fields to the number of bytes in the complete
+   structure exceeds this parameter, then block copies are not used.
+   The default is 75%.  */
+DEFPARAM (PARAM_SRA_FIELD_STRUCTURE_RATIO,
+	  "sra-field-structure-ratio",
+	  "The threshold ratio between instantiated fields and the total structure size.",
+	  75)
+
 /* The single function inlining limit. This is the maximum size
    of a function counted in internal gcc instructions (not in
    real machine instructions) that is eligible for inlining
diff --git a/gcc/params.h b/gcc/params.h
index b17625e..0ebb972 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -82,6 +82,10 @@ typedef enum compiler_param
   (compiler_params[(int) ENUM].value)
 
 /* Macros for the various parameters.  */
+#define SRA_MAX_STRUCTURE_SIZE \
+  PARAM_VALUE (PARAM_SRA_MAX_STRUCTURE_SIZE)
+#define SRA_FIELD_STRUCTURE_RATIO \
+  PARAM_VALUE (PARAM_SRA_FIELD_STRUCTURE_RATIO)
 #define MAX_INLINE_INSNS_SINGLE \
   PARAM_VALUE (PARAM_MAX_INLINE_INSNS_SINGLE)
 #define MAX_INLINE_INSNS \
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1329715..8d984cc 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2004-10-28  Ben Elliston  <bje@au.ibm.com>
+
+	* gcc.dg/tree-ssa/sra-1.c: Pass --param sra-max-structure-size.
+
 2004-10-27  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* gcc.dg/cpp/direct2.c: Cope with different bison 'parse' or
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sra-1.c b/gcc/testsuite/gcc.dg/tree-ssa/sra-1.c
index 652f402..c018fbb 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/sra-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sra-1.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */ 
-/* { dg-options "-O1 -fdump-tree-optimized" } */
+/* { dg-options "-O1 -fdump-tree-optimized --param sra-max-structure-size=32" } */
 
 /* Tests for SRA. */
 
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index 7519c3c..9fd40f9 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -48,6 +48,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "target.h"
 /* expr.h is needed for MOVE_RATIO.  */
 #include "expr.h"
+#include "params.h"
 
 
 /* This object of this pass is to replace a non-addressable aggregate with a
@@ -1292,6 +1293,14 @@ decide_block_copy (struct sra_elt *elt)
 	{
 	  unsigned HOST_WIDE_INT full_size, inst_size = 0;
 	  unsigned int inst_count;
+	  unsigned int max_size;
+
+	  /* If the sra-max-structure-size parameter is 0, then the
+	     user has not overridden the parameter and we can choose a
+	     sensible default.  */
+	  max_size = SRA_MAX_STRUCTURE_SIZE
+	    ? SRA_MAX_STRUCTURE_SIZE
+	    : MOVE_RATIO * UNITS_PER_WORD;
 
 	  full_size = tree_low_cst (size_tree, 1);
 
@@ -1302,14 +1311,14 @@ decide_block_copy (struct sra_elt *elt)
 
 	  /* If the structure is small, and we've made copies, go ahead
 	     and instantiate, hoping that the copies will go away.  */
-	  if (full_size <= (unsigned) MOVE_RATIO * UNITS_PER_WORD
+	  if (full_size <= max_size
 	      && elt->n_copies > elt->n_uses)
 	    use_block_copy = false;
 	  else
 	    {
 	      inst_count = sum_instantiated_sizes (elt, &inst_size);
 
-	      if (inst_size * 4 >= full_size * 3)
+	      if (inst_size * 100 >= full_size * SRA_FIELD_STRUCTURE_RATIO)
 		use_block_copy = false;
 	    }