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From: "steven at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/54133] regrename introduces additional dependencies
Date: Wed, 01 Aug 2012 11:58:00 -0000 [thread overview]
Message-ID: <bug-54133-4-G3gu0L5xMU@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-54133-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54133
--- Comment #4 from Steven Bosscher <steven at gcc dot gnu.org> 2012-08-01 11:58:00 UTC ---
Created attachment 27918
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27918
Hack regmove to do limited propagation of hard regs
I have a patch to make the propagation happen in regmove, resulting in the
following RTL in the IRA dump:
78 r177:DF=r0:DF
80 [sp:SI]=r166:DF
81 [sp:SI+0x8]=r168:DF
82 [sp:SI+0x10]=r170:DF
84 r2:DF=r164:DF
85 r0:DF=call [`bar'] argc:0x18
REG_DEAD: r2:DF
REG_UNUSED: r0:DF
86 [sp:SI]=r167:DF
87 [sp:SI+0x8]=r169:DF
88 [sp:SI+0x10]=r171:DF
89 r0:DF=r177:DF
REG_DEAD: r177:DF
90 r2:DF=r165:DF
91 r0:DF=call [`bar'] argc:0x18
But now IRA decides to spill r177 to memory:
Allocno a5r177 of GENERAL_REGS(9) has 4 avail. regs 4-7, node: 4-7 obj
0 (confl regs = 0-3 8-102), obj 1 (confl regs = 0-3 8-102)
Pushing a5(r177,l0)(potential spill: pri=469, cost=38000)
Making a1(r159,l0) colorable
Making a2(r172,l0) colorable
Making a3(r163,l0) colorable
Pushing a1(r159,l0)(cost 32000)
Pushing a3(r163,l0)(cost 40000)
Pushing a2(r172,l0)(cost 88000)
Popping a2(r172,l0) -- assign reg 4
Popping a3(r163,l0) -- assign reg 5
Popping a1(r159,l0) -- assign reg 6
Popping a5(r177,l0) -- (memory is more profitable 32000 vs 2147483647)
spill
Popping a0(r175,l0) -- assign reg 7
This makes the inner loop 2 instructions smaller, but I haven't investigated
whether that's an improvement or not.
next prev parent reply other threads:[~2012-08-01 11:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-31 6:59 [Bug rtl-optimization/54133] New: " amker.cheng at gmail dot com
2012-07-31 8:01 ` [Bug rtl-optimization/54133] " steven at gcc dot gnu.org
2012-08-01 7:50 ` amker.cheng at gmail dot com
2012-08-01 10:14 ` steven at gcc dot gnu.org
2012-08-01 11:58 ` steven at gcc dot gnu.org [this message]
2012-08-01 13:49 ` amker.cheng at gmail dot com
2012-08-02 7:22 ` ebotcazou at gcc dot gnu.org
2012-08-02 10:18 ` amker.cheng at gmail dot com
2012-09-25 7:45 ` amker.cheng at gmail dot com
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