Dictation of strength reduction in source is required for adequate performance
on this target. The same source "optimization" is counter-productive for ia32.
This is a portion of the diff file between 2 versions of
libgfortran/generated/matmul_r8.c.
for (n = 0; n < count; n++)
{
! abase_n = abase + n * aystride;
sum += abase_n[x] * bbase_y[n];
sum1 += abase_n[x+1] * bbase_y[n];
--- 199,208 ----
{
rtype_name sum = 0, sum1 = 0;
+ index_type nay = 0;
for (n = 0; n < count; n++)
{
! /* FIXME: gcc ought to strength reduce from n * aystride */
! abase_n = abase + nay;
! nay += aystride;
sum += abase_n[x] * bbase_y[n];
sum1 += abase_n[x+1] * bbase_y[n];
--
Summary: missed strength reduction costs performance
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tprince at computer dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: ia64-unknown-linux-gnu
GCC host triplet: ia64-unknown-linux-gnu
GCC target triplet: ia64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845
