This is the mail archive of the
mailing list for the GCC project.
Re: [patch] Fix PR target/62631
- From: Jeff Law <law at redhat dot com>
- To: Eric Botcazou <ebotcazou at adacore dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 06 Feb 2015 00:56:22 -0700
- Subject: Re: [patch] Fix PR target/62631
- Authentication-results: sourceware.org; auth=none
- References: <15644575 dot zb4QZkAvgm at polaris>
On 02/05/15 08:53, Eric Botcazou wrote:
this is the failure of gcc.dg/tree-ssa/ivopts-lt-2.c on SPARC 64-bit, but I
think that the problem is actually generic: get_shiftadd_cost only calls
shiftadd_cost to get the cost of a "shift-add", which is actually a multiply
by a power-of-2 operation. Since SPARC doesn't have a lea-like instruction,
shiftadd_cost returns a very high cost, about 3 times the cost of an add+shift
sequence which is what the RTL expander will generate for this operation.
So I think that get_shiftadd_cost should mimic the algorithms in expmed.c and
use the minimum of shiftadd_cost and (add_cost + shift_cost) for the cost of
the shift-add operation.
Tested on x86-64, SPARC and SPARC64, OK for the mainline?
2015-02-05 Eric Botcazou <email@example.com>
* tree-ssa-loop-ivopts.c (get_shiftadd_cost): Use the mininum of costs
of shift-add and (add + shift) operations. Rename local variable.