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30 Commits

Author SHA1 Message Date
Clifford Wolf 42190207b4 Improve opt_expr and opt_clean handling of (partially) undriven and/or unused wires, fixes #981 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2019-05-03 14:25:01 +02:00
Clifford Wolf 9d117eba9d Add handling of init attributes in "opt_expr -undriven" 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2019-04-30 14:46:12 +02:00
Clifford Wolf e158ea2097 Add log_debug() framework 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2019-04-22 17:25:52 +02:00
Clifford Wolf f806b95ed6 Improve handling of and-with-1 and or-with-0 in opt_expr, fixes #327 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2019-03-14 20:52:00 +01:00
Clifford Wolf 0fc6e2bfcf
Merge pull request #770 from whitequark/opt_expr_cmp 
opt_expr: refactor and improve simplification of comparisons
 2019-01-02 17:34:04 +01:00
whitequark bf8db55ef3 opt_expr: improve simplification of comparisons with large constants. 
The idea behind this simplification is that a N-bit signal X being
compared with an M-bit constant where M>N and the constant has Nth
or higher bit set, it either always succeeds or always fails.

However, the existing implementation only worked with one-hot signals
for some reason. It also printed incorrect messages.

This commit adjusts the simplification to have as much power as
possible, and fixes other bugs.
 2019-01-02 15:45:28 +00:00
whitequark efa278e232 Fix typographical and grammatical errors and inconsistencies. 
The initial list of hits was generated with the codespell command
below, and each hit was evaluated and fixed manually while taking
context into consideration.

    DIRS="kernel/ frontends/ backends/ passes/ techlibs/"
    DIRS="${DIRS} libs/ezsat/ libs/subcircuit"
    codespell $DIRS -S *.o -L upto,iff,thru,synopsys,uint

More hits were found by looking through comments and strings manually.
 2019-01-02 13:12:17 +00:00
whitequark 4fd458290c opt_expr: refactor simplification of unsigned X<onehot and X>=onehot. NFCI. 2019-01-02 05:11:29 +00:00
whitequark 9e9846a6ea opt_expr: refactor simplification of signed X>=0 and X<0. NFCI. 2019-01-02 03:01:25 +00:00
whitequark 8e53d2e0bf opt_expr: simplify any unsigned comparisons with all-0 and all-1. 
Before this commit, only unsigned comparisons with all-0 would be
simplified. This commit also makes the code handling such comparisons
to be more rigorous and not abort on unexpected input.
 2019-01-02 02:45:49 +00:00
Clifford Wolf 643f858acf Bugfix in opt_expr handling of a<0 and a>=0 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2018-12-06 07:29:21 +01:00
Henner Zeller 3aa4484a3c Consistent use of 'override' for virtual methods in derived classes. 
o Not all derived methods were marked 'override', but it is a great
  feature of C++11 that we should make use of.
o While at it: touched header files got a -*- c++ -*- for emacs to
  provide support for that language.
o use YS_OVERRIDE for all override keywords (though we should probably
  use the plain keyword going forward now that C++11 is established)
 2018-07-20 23:51:06 -07:00
Clifford Wolf 587056447e Add optimization of tristate buffer with constant control input 
Signed-off-by: Clifford Wolf <clifford@clifford.at>
 2018-05-12 15:18:27 +02:00
Clifford Wolf 68c42f3a19 Don't track , ... contradictions through x/z-bits 2017-08-25 16:18:17 +02:00
Clifford Wolf db6d78a186 Add removing of redundant pairs of bits in ==, ===, !=, and !== to opt_expr 2017-08-25 16:02:15 +02:00
Clifford Wolf 649bb9374f Add "opt_expr -fine" feature to remove neutral bits from reduce and logic operators 2017-07-26 18:28:55 +02:00
Clifford Wolf 0a02cdb93b Fix and_or_buffer optimization in opt_expr for signed operators 2017-07-01 16:05:26 +02:00
Larry Doolittle 2021ddecb3 Squelch trailing whitespace 2017-04-12 15:11:09 +02:00
Clifford Wolf 95dae6d416 Fixed some "used uninitialized" warnings in opt_expr 2017-02-11 10:50:48 +01:00
Clifford Wolf a5bfeb9e07 Add optimization of (a && 1'b1) and (a || 1'b0) 2017-02-11 10:05:00 +01:00
C-Elegans 94b272077d Fix issue #306, "Bug in opt -full" 
Add check for whether the high bit in the constant expression is greater
than the width of the variable, and optimizes that to a constant 1 or
0
 2017-02-10 10:38:02 -05:00
Clifford Wolf ffbe8d41f3 Fix indenting and log messages in code merged from opt_compare_pr 2017-01-31 16:20:56 +01:00
C-Elegans a94c3694d7 Refactor and generalize the comparision optimization 
Generalizes the optimization to:
a < C,
a >= C,
C > a,
C <= a
 2017-01-30 17:52:16 -05:00
C-Elegans 2fa0fd4a37 Do not use b.as_int() in calculation of bit set 2017-01-21 12:58:26 -05:00
C-Elegans 84f9cd0025 Optimize compares to powers of 2 
Remove opt_compare and put comparison pass in opt_expr

assuming a [7:0] is unsigned
a >= (1<<x) becomes |a[7:x]
a <  (1<<x) becomes !a[7:x]

Additionally:
a >= 0 becomes constant true,
a < 0 becomes constant false

delete opt_compare.cc
revert opt.cc to commit b7cfb7dbd (remove opt_compare step)
 2017-01-16 13:45:50 -05:00
Clifford Wolf 11f7b8a2a1 Added opt_expr support for div/mod by power-of-two 2016-05-29 12:17:36 +02:00
Clifford Wolf 0bc95f1e04 Added "yosys -D" feature 2016-04-21 23:28:37 +02:00
Clifford Wolf f38ca3e18f Improvements in opt_expr 2016-04-21 14:23:04 +02:00
Clifford Wolf e2f6d61c00 Typo fixes in opt_expr and opt_merge 2016-03-31 09:56:56 +02:00
Clifford Wolf 1d0f0d668a Renamed opt_const to opt_expr 2016-03-31 08:46:56 +02:00