optimization/4888: incorrect code with -Ox, x >= 2

[jfran@clip.dia.fi.upm.es]

>Number:         4888
>Category:       optimization
>Synopsis:       incorrect code with -Ox, x >= 2
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Nov 16 04:06:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     jfran
>Release:        gcc >=2.96 <=3.0.2
>Organization:
>Environment:

>Description:
With optimizations enabled, "f=x; y=*(type*)&f;" reads garbage 
on 'y' unless 'type'=='char' (problem with memory alias?) 

"f=x; g(); y=*(type*)&f;" works fine if g() is not
inlined.
>How-To-Repeat:
Compile with -O0, execute.
Compile with -O2, execute.
Uncomment the commented line.
Test again.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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