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[Bug tree-optimization/17549] [4.0 Regression] 10% increase in codesize with C code compared to GCC 3.3
- From: "rth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 7 Feb 2005 23:36:20 -0000
- Subject: [Bug tree-optimization/17549] [4.0 Regression] 10% increase in codesize with C code compared to GCC 3.3
- References: <20040918113641.17549.miguel55angel@hotmail.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From rth at gcc dot gnu dot org 2005-02-07 23:36 -------
Subject: Re: [4.0 Regression] 10% increase in codesize with C code compared to GCC 3.3
On Mon, Feb 07, 2005 at 11:13:27PM -0000, steven at gcc dot gnu dot org wrote:
> x = a + b;
> x = x * a;
> x = x * b;
...
> After Coalescing:
...
> Partition 2 (x_3 - 3 )
> Partition 3 (x_4 - 4 )
> Partition 4 (x_5 - 5 )
That is curious. Certainly not the way I'd have expected things to work.
Why are we not coalescing here? Do we think that x_4 as an input to the
same insn that creates x_5 means that the two conflict? Unless someone
can convince me otherwise, I'd call this a bug.
r~
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17549