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* [Bug middle-end/35361] New: Missing dead store elimination for statics
@ 2008-02-25 5:24 xinliangli at gmail dot com
2008-02-25 11:40 ` [Bug middle-end/35361] Missing IPA DCE and DSE rguenth at gcc dot gnu dot org
0 siblings, 1 reply; 2+ messages in thread
From: xinliangli at gmail dot com @ 2008-02-25 5:24 UTC (permalink / raw)
To: gcc-bugs
// David Li
Gcc is solid in performing dead function elimination and dead variable
elimination for statics. It handles cases when a dead variable is referenced
(via initializer) by other dead variables pretty well. The missing
opportunities noticed is that it fails to discover dead stores to static
variables where are never used -- thus missing the dead variable elimination
...
Example 1:
static int s;
static int* p =&s;
int foo()
{
p = 0; // Dead, not eliminated
}
Example 2:
static int g = 10;
static int* gp = &g;
int foo()
{
gp = 0; // Dead store
return g; // should be const proped
}
--
Summary: Missing dead store elimination for statics
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: xinliangli at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35361
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug middle-end/35361] Missing IPA DCE and DSE
2008-02-25 5:24 [Bug middle-end/35361] New: Missing dead store elimination for statics xinliangli at gmail dot com
@ 2008-02-25 11:40 ` rguenth at gcc dot gnu dot org
0 siblings, 0 replies; 2+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-25 11:40 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2008-02-25 11:39 -------
It looks like this needs IPA DCE/DSE.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |missed-optimization
Last reconfirmed|0000-00-00 00:00:00 |2008-02-25 11:39:30
date| |
Summary|Missing dead store |Missing IPA DCE and DSE
|elimination for statics |
Version|unknown |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35361
^ permalink raw reply [flat|nested] 2+ messages in thread
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2008-02-25 5:24 [Bug middle-end/35361] New: Missing dead store elimination for statics xinliangli at gmail dot com
2008-02-25 11:40 ` [Bug middle-end/35361] Missing IPA DCE and DSE rguenth at gcc dot gnu dot org
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