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Incorrect results with partially out-of-bounds part select #823

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veripoolbot opened this issue Sep 23, 2014 · 2 comments
Closed

Incorrect results with partially out-of-bounds part select #823

veripoolbot opened this issue Sep 23, 2014 · 2 comments

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@veripoolbot
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@veripoolbot veripoolbot commented Sep 23, 2014


Author Name: Clifford Wolf (@cliffordwolf)
Original Redmine Issue: 823 from https://www.veripool.org
Original Date: 2014-09-23
Original Assignee: Wilson Snyder (@wsnyder)


This should return y=4'b100x for a=1, but verilator returns y=0 instead
(the MSB should be '1', obviously we don't care about the 'x' in the LSB that
is the result of the (by one bit) out-of-bounds part select):

 module issue_057(a, y);
   input [2:0] a;
   output [3:0] y;
   localparam [5:15] p = 51681708;
   assign y = p[15 + a -: 5];
 endmodule

Self-contained test case:

http://svn.clifford.at/handicraft/2014/verilatortest/test020.v

http://svn.clifford.at/handicraft/2014/verilatortest/test020_tb.v

http://svn.clifford.at/handicraft/2014/verilatortest/test020.cc

http://svn.clifford.at/handicraft/2014/verilatortest/test020.sh

This is with git e8edbad (verilator_3_864).

@veripoolbot
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@veripoolbot veripoolbot commented Nov 9, 2014


Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2014-11-09T23:39:21Z


Fixed in git towards 3.865.

@veripoolbot
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@veripoolbot veripoolbot commented Nov 15, 2014


Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2014-11-15T13:46:21Z


In 3.866.

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