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[Bug target/34903] -Os code size regression
- From: "dje at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 22 Jan 2008 15:59:54 -0000
- Subject: [Bug target/34903] -Os code size regression
- References: <bug-34903-15672@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #9 from dje at gcc dot gnu dot org 2008-01-22 15:59 -------
GCC does not use the load and store multiple instructions because the source
file declares r29 a global variable:
register volatile gd_t *gd asm ("r29");
The bug fix mentioned above inhibits GCC from using lmw/stmw if global
registers are present in the contiguous register sequence because GCC
incorrectly would overwrite the register. If the register variable declaration
is removed, GCC uses the lmw/stmw instructions. r29 is a bad choice for a
global register variable.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34903