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Re: PATCH - [tree-ssa] regrouping of expression tree for single multiply add.
- From: Fariborz Jahanian <fjahanian at apple dot com>
- To: law at redhat dot com
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Diego Novillo <dnovillo at redhat dot com>, Roger Sayle <roger at eyesopen dot com>
- Date: Wed, 24 Mar 2004 17:36:38 -0800
- Subject: Re: PATCH - [tree-ssa] regrouping of expression tree for single multiply add.
- References: <200403241917.i2OJHonL011901@speedy.slc.redhat.com>
On Mar 24, 2004, at 11:17 AM, email@example.com wrote:
In message <firstname.lastname@example.org>, Diego
On Mon, 2004-03-22 at 21:25, Fariborz Jahanian wrote:And I think there's an excellent argument against this kind of
tree-ssa because it is an 'improvement' patch and I believe mainline
isOn the contrary. It is tree-ssa the frozen one. mainline is in
frozen for improvement patches.
stage1. If this goes in mainline, tree-ssa will inherit it at the
OK for tree-ssa?No. Try mainline.
for the mainline as well, at least for FP types.
What is the argument? If issue is correctness for corner cases, is there
additional gcc flag; besides -ffast-math, which need be checked for?
This kind of transformation makes sense for integers though :-)
some mips targets that have integer madd and several targets now have
1 integer multiply pipeline. Thus stuff like
a * b * c * d which is implemented as (((a * b) * c) * d) can be
profitably turned into (a * b) * (c * d).