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* [Bug tree-optimization/42635] New: no-op conversions hinder if-conversion
@ 2010-01-06 15:16 rguenth at gcc dot gnu dot org
2010-01-06 15:17 ` [Bug tree-optimization/42635] " rguenth at gcc dot gnu dot org
0 siblings, 1 reply; 2+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2010-01-06 15:16 UTC (permalink / raw)
To: gcc-bugs
The following two functions are not if-converted at the tree level (the 2nd
example happens a lot from VEC code via VEC_BASE):
int *bar (char *p)
{
int *q;
if (p)
q = (int *)p;
else
q = (int *)0;
return q;
}
struct X { int q; };
int *foo (struct X *p)
{
int *q;
if (p)
q = &p->q;
else
q = (int *)0;
return q;
}
before phiopt1 we have
bar (char * p)
{
int * q;
<bb 2>:
if (p_2(D) != 0B)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
q_3 = (int *) p_2(D);
<bb 4>:
# q_1 = PHI <q_3(3), 0B(2)>
return q_1;
which can be optimized to just
<bb 2>:
return (int *) p_2(D);
well - with a separate stmt for the conversion.
--
Summary: no-op conversions hinder if-conversion
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42635
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug tree-optimization/42635] no-op conversions hinder if-conversion
2010-01-06 15:16 [Bug tree-optimization/42635] New: no-op conversions hinder if-conversion rguenth at gcc dot gnu dot org
@ 2010-01-06 15:17 ` rguenth at gcc dot gnu dot org
0 siblings, 0 replies; 2+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2010-01-06 15:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2010-01-06 15:17 -------
Created an attachment (id=19485)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19485&action=view)
testcase using vec.h
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42635
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-01-06 15:16 [Bug tree-optimization/42635] New: no-op conversions hinder if-conversion rguenth at gcc dot gnu dot org
2010-01-06 15:17 ` [Bug tree-optimization/42635] " rguenth at gcc dot gnu dot org
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