[Gmp-commit] /var/hg/gmp: Rewrite code for limiting mpn_sqr_basecase use.

[mercurial at gmplib.org]

details:   /var/hg/gmp/rev/422bb4bc9ce9
changeset: 14620:422bb4bc9ce9
user:      Torbjorn Granlund <tege at gmplib.org>
date:      Sat Feb 11 10:57:57 2012 +0100
description:
Rewrite code for limiting mpn_sqr_basecase use.

diffstat:

 ChangeLog              |   9 +++++++++
 mpn/generic/powm_sec.c |  21 ++++++++++-----------
 2 files changed, 19 insertions(+), 11 deletions(-)

diffs (77 lines):

diff -r 2cdfeac5befd -r 422bb4bc9ce9 ChangeLog
--- a/ChangeLog	Fri Feb 10 22:32:30 2012 +0100
+++ b/ChangeLog	Sat Feb 11 10:57:57 2012 +0100
@@ -94,6 +94,15 @@
 	* tests/cxx/t-cxx11.cc: New file.
 	* tests/cxx/Makefile.am: Added t-cxx11.
 
+2012-01-31  Torbjorn Granlund  <tege at gmplib.org>
+
+	* mpn/generic/powm_sec.c (SQR_BASECASE_LIM): New name for
+	SQR_BASECASE_MAX.
+	(SQR_BASECASE_LIM, fat variant): Define to read __gmpn_cpuvec.
+	(SQR_BASECASE_LIM, native variant): Define to SQR_TOOM2_THRESHOLD
+	straight, without arithmetic.
+	(mpn_local_sqr): Use BELOW_THRESHOLD as per Marco's suggestion.
+
 2012-01-30  Torbjorn Granlund  <tege at gmplib.org>
 
 	* tests/mpz/t-powm.c: Ensure all sizes are seen.
diff -r 2cdfeac5befd -r 422bb4bc9ce9 mpn/generic/powm_sec.c
--- a/mpn/generic/powm_sec.c	Fri Feb 10 22:32:30 2012 +0100
+++ b/mpn/generic/powm_sec.c	Sat Feb 11 10:57:57 2012 +0100
@@ -7,7 +7,7 @@
    SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS ALMOST
    GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
 
-Copyright 2007, 2008, 2009, 2011 Free Software Foundation, Inc.
+Copyright 2007, 2008, 2009, 2011, 2012 Free Software Foundation, Inc.
 
 This file is part of the GNU MP Library.
 
@@ -90,7 +90,7 @@
 
 #if ! HAVE_NATIVE_mpn_sqr_basecase
 /* The limit of the generic code is SQR_TOOM2_THRESHOLD.  */
-#define SQR_BASECASE_MAX  SQR_TOOM2_THRESHOLD
+#define SQR_BASECASE_LIM  SQR_TOOM2_THRESHOLD
 #endif
 
 #if HAVE_NATIVE_mpn_sqr_basecase
@@ -99,20 +99,19 @@
    mpn_sqr_basecase, it comes from SQR_TOOM2_THRESHOLD_MAX in the assembly
    file.  An assembly mpn_sqr_basecase that does not define it, should allow
    any size.  */
-#define SQR_BASECASE_MAX  (SQR_TOOM2_THRESHOLD - 1)
+#define SQR_BASECASE_LIM  SQR_TOOM2_THRESHOLD
 #endif
 #endif
 
 #ifdef WANT_FAT_BINARY
-/* For fat builds, we would need to quantify over all mpn_sqr_basecase limit
-   that may appear in __gmpn_cpuvec.  This asks for some configure.in hacking.
-   For now, define a safe limit which all mpn_sqr_basecase will handle.
-   FIXME!  */
-#define SQR_BASECASE_MAX 32
+/* For fat builds, we use SQR_TOOM2_THRESHOLD which will expand to a read from
+   __gmpn_cpuvec.  Perhaps any possible sqr_basecase.asm allow any size, and we
+   limit the use unnecessarily.  We cannot tell, so play it safe.  FIXME.  */
+#define SQR_BASECASE_LIM  SQR_TOOM2_THRESHOLD
 #endif
 
-#ifndef SQR_BASECASE_MAX
-/* If SQR_BASECASE_MAX is now not defined, use mpn_sqr_basecase for any operand
+#ifndef SQR_BASECASE_LIM
+/* If SQR_BASECASE_LIM is now not defined, use mpn_sqr_basecase for any operand
    size.  */
 #define mpn_local_sqr(rp,up,n,tp) mpn_sqr_basecase(rp,up,n)
 #else
@@ -126,7 +125,7 @@
   ASSERT (n >= 1);
   ASSERT (! MPN_OVERLAP_P (rp, 2*n, up, n));
 
-  if (n <= SQR_BASECASE_MAX)
+  if (BELOW_THRESHOLD (n, SQR_BASECASE_LIM))
     {
       mpn_sqr_basecase (rp, up, n);
       return;