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IDProjectCategoryView StatusDate SubmittedLast Update
0001372Frama-CPlug-in > Evapublic2013-02-20 09:232013-04-19 11:05
ReporterAnne 
Assigned Toyakobowski 
PrioritynormalSeverityminorReproducibilityhave not tried
StatusclosedResolutionfixed 
PlatformOSOS Version
Product VersionFrama-C Oxygen-20120901 
Target VersionFixed in VersionFrama-C Fluorine-20130401 
Summary0001372: Extern function vs extern variable to get a random value
DescriptionI am trying to build an environment to represent the inputs of the application that I study with the value analysis. I tried different things : ~~~~~~~~~~~~~ 1/ double v = ext_double; assert (v <= 100); with the global variable : extern double ext_double; gives what I want: v ? [-1.79769313486e+308 .. 100.] ~~~~~~~~~~~~~ 2/ double v = rand_double (); assert (v <= 100); with: //@ assigns \result \from \nothing; extern double rand_double (); gives a warning that I don't understand: toto.c:25:[value] warning: converting value to float: assert(Ook) and doesn't use the assert (?): v ? [--..--] ~~~~~~~~~~~~~ 3/ double v = rand_double_post (); assert (v <= 100); with: //@ assigns \result \from \nothing; ensures \result <= 100; extern double rand_double_post (); gives the same warning twice: toto.c:21:[value] warning: converting value to float: assert(Ook) toto.c:25:[value] warning: converting value to float: assert(Ook) and doesn't work either: v ? [--..--] ~~~~~~~~~~~~~ 4/ double v = rand_double_var (); assert (v <= 100); with: extern double rand_double_var () { return ext_double; } gives no warning, and works as expected: v ? [-1.79769313486e+308 .. 100.] ~~~~~~~~~~~~~ Shouldn't the four initializations give the same results ? Sorry if it is about something that I didn't understand...
Additional InformationWith the attached file, see previous results with the command: $ frama-c -val toto.c -cpp-extra-args="-DT=1" with different values of T (1 to 4).
TagsNo tags attached.
Attached Filesc file icon toto.c [^] (606 bytes) 2013-02-20 09:23 [Show Content]

- Relationships

-  Notes
(0003703)
Anne (reporter)
2013-02-21 08:06

Sorry for the duplication, but #1164 seems to be private.
(0003704)
yakobowski (manager)
2013-02-21 09:51

No problem, I actually opened 1164. This issue is related to the handling of NaN/Infinities. Value no not propagate, and instead raises an alarm, but it can still encounter trough external functions or unsafe casts.
(0003719)
yakobowski (manager)
2013-02-28 00:00

This bug will be fixed in Fluorine. - the mysterious messages "converting value to float: assert(Ook)" do not appear anymore - at the end of the analysis, v IN [-1.79769313486e+308 .. 100.] holds in all four cases. - for cases 2 and 3, there is an alarm on the first read of v at ligne 24. This takes into account the fact that rand_double/rand_double_post may return a NaN or an infinity. - it is currently not possible to use assertions to express that a NaN/Infty float is within a range.

- Issue History
Date Modified Username Field Change
2013-02-20 09:23 Anne New Issue
2013-02-20 09:23 Anne Status new => assigned
2013-02-20 09:23 Anne Assigned To => yakobowski
2013-02-20 09:23 Anne File Added: toto.c
2013-02-20 22:37 yakobowski Relationship added duplicate of 0001164
2013-02-21 08:06 Anne Note Added: 0003703
2013-02-21 09:51 yakobowski Note Added: 0003704
2013-02-21 17:43 Anne Note Added: 0003705
2013-02-21 18:58 signoles Note Added: 0003706
2013-02-22 07:59 Anne Note Added: 0003707
2013-02-27 23:50 yakobowski Note Deleted: 0003705
2013-02-27 23:50 yakobowski Note Deleted: 0003706
2013-02-27 23:50 yakobowski Note Deleted: 0003707
2013-02-28 00:00 yakobowski Note Added: 0003719
2013-02-28 00:00 yakobowski Status assigned => resolved
2013-02-28 00:00 yakobowski Resolution open => fixed
2013-04-19 11:05 signoles Fixed in Version => Frama-C Fluorine
2013-04-19 11:05 signoles Status resolved => closed
2018-01-12 14:26 signoles Category Plug-in > value analysis => Plug-in > Eva


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