Correct elaboration of network constants.
Constant propagation incorrectly elided an entire constant net node if only the LSB of the driven vector was HiZ. This caused the entire vector to look like HiZ. Also, the code generator for writing the constant values missed bits. Signed-off-by: Stephen Williams <steve@icarus.com>
This commit is contained in:
Stephen Williams
parent
9ed8614131
commit
08028177fe
93
cprop.cc
93
cprop.cc
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@ -16,16 +16,13 @@
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#ifdef HAVE_CVS_IDENT
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#ident "$Id: cprop.cc,v 1.56 2007/03/07 00:38:15 steve Exp $"
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#endif
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# include "config.h"
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# include "netlist.h"
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# include "netmisc.h"
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# include "functor.h"
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# include <assert.h>
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# include "ivl_assert.h"
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@ -846,15 +843,17 @@ struct cprop_dc_functor : public functor_t {
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void cprop_dc_functor::lpm_const(Design*des, NetConst*obj)
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{
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// 'bz constant values drive high impedance to whatever is
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// connected to it. In other words, it is a noop.
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// connected to it. In other words, it is a noop. But that is
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// only true if *all* the bits of the vectors.
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{ unsigned tmp = 0;
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for (unsigned idx = 0 ; idx < obj->pin_count() ; idx += 1)
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ivl_assert(*obj, obj->pin_count()==1);
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for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
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if (obj->value(idx) == verinum::Vz) {
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obj->pin(idx).unlink();
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tmp += 1;
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}
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}
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if (tmp == obj->pin_count()) {
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if (tmp == obj->width()) {
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delete obj;
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return;
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}
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@ -948,81 +947,3 @@ void cprop(Design*des)
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des->functor(&dc);
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}
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/*
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* $Log: cprop.cc,v $
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* Revision 1.56 2007/03/07 00:38:15 steve
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* Lint fixes.
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*
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* Revision 1.55 2006/05/24 04:32:57 steve
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* Fix handling of ternary-to-bufif0 constant propagation.
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*
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* Revision 1.54 2005/07/15 19:22:52 steve
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* bufif enable is LOGIC.
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*
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* Revision 1.53 2005/05/15 04:44:30 steve
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* Disable obsolete logic constant fixup code.
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*
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* Revision 1.52 2005/04/24 23:44:01 steve
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* Update DFF support to new data flow.
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*
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* Revision 1.51 2005/02/12 22:52:45 steve
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* Fix copyright notice.
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*
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* Revision 1.50 2005/02/12 06:25:40 steve
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* Restructure NetMux devices to pass vectors.
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* Generate NetMux devices from ternary expressions,
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* Reduce NetMux devices to bufif when appropriate.
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*
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* Revision 1.49 2005/01/16 04:20:32 steve
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* Implement LPM_COMPARE nodes as two-input vector functors.
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*
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* Revision 1.48 2004/12/11 02:31:25 steve
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* Rework of internals to carry vectors through nexus instead
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* of single bits. Make the ivl, tgt-vvp and vvp initial changes
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* down this path.
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*
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* Revision 1.47 2004/02/20 18:53:34 steve
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* Addtrbute keys are perm_strings.
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*
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* Revision 1.46 2003/11/08 17:53:34 steve
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* Do not remove constants accessible to VPI.
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*
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* Revision 1.45 2003/10/31 02:40:06 steve
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* Donot elide FF that has set or clr connections.
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*
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* Revision 1.44 2003/04/25 05:06:32 steve
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* Handle X values in constant == nets.
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*
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* Revision 1.43 2003/03/06 00:28:41 steve
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* All NetObj objects have lex_string base names.
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*
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* Revision 1.42 2003/02/26 01:29:24 steve
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* LPM objects store only their base names.
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*
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* Revision 1.41 2003/01/30 16:23:07 steve
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* Spelling fixes.
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*
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* Revision 1.40 2003/01/27 05:09:17 steve
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* Spelling fixes.
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*
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* Revision 1.39 2002/08/20 04:12:22 steve
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* Copy gate delays when doing gate delay substitutions.
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*
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* Revision 1.38 2002/08/12 01:34:58 steve
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* conditional ident string using autoconfig.
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*
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* Revision 1.37 2002/06/25 01:33:22 steve
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* Cache calculated driven value.
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*
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* Revision 1.36 2002/06/24 01:49:38 steve
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* Make link_drive_constant cache its results in
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* the Nexus, to improve cprop performance.
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*
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* Revision 1.35 2002/05/26 01:39:02 steve
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* Carry Verilog 2001 attributes with processes,
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* all the way through to the ivl_target API.
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*
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* Divide signal reference counts between rval
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* and lval references.
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*/
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@ -412,17 +412,8 @@ static char* draw_C4_to_string(ivl_net_const_t cptr)
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dp += strlen(dp);
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for (idx = 0 ; idx < ivl_const_width(cptr) ; idx += 1) {
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switch (bits[ivl_const_width(cptr)-idx-1]) {
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case '0':
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*dp++ = '0';
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break;
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case '1':
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*dp++ = '1';
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break;
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default:
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*dp++ = bits[idx];
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break;
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}
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char bitchar = bits[ivl_const_width(cptr)-idx-1];
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*dp++ = bitchar;
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assert((dp - result) < result_len);
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}
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