c/6192: gcc array reference incorrect on multi-dimensional array

[me at andydunn dot ca]

>Number:         6192
>Category:       c
>Synopsis:       gcc array reference incorrect on multi-dimensional array
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 05 12:06:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Andrew Michael Dunn
>Release:        gcc-2.96, also others older
>Organization:
>Environment:
RedHat 7.0 2.2.16-22 kernel, also others (eg. Caldera 2.2.5)
>Description:
When accessing a two-dimensional array of ints, writing to
any row (first dimension) of the array then reading from
any row returns the value written (see example provided).

Accessing the array memory space as a linear single-dimension
array of ints proves that only the first row gets written,
regardless of the array index, and only the first row gets
read.

ie.  int array[3,2]

assignment   array[1,0] = 3

the 3 actually gets written into array[0,0]

inspecting    array[0,0], array[1,0] or array[2,0]

all of these return the value 3 (which was written
only into array[0,0] originally


Single-dimension int arrays do not have this problem

>How-To-Repeat:
See attached xtest.c - very reproducible on multiple
machines, kernel revs, gcc versions, etc.
>Fix:

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