http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57962
Bug ID: 57962
Summary: Missed Optimization for Superword Level Parallelism
Product: gcc
Version: 4.7.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: freddie at witherden dot org
Created attachment 30541
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30541&action=edit
Sample code.
GCC 4.7.3 and 4.8.1 both miss an optimization when compiling the attached test
case using:
gcc -Ofast -march=corei7-avx test.c -S
By loading the components of ul and fl into the bottom half of an xmm register
and ur and fr into the corresponding top half it is possible to compute
disf_inv_impl(ul, fl) and disf_inv_impl(ur, fr) in a single hit. Horizontal
instructions can then be used to add the various fl and fr components together.
