Remove some wasteful and excess scans of the Nexus of some links,
and remove dead code so we can see what we're doing. Also inline
some commonly used and trivial functions.
Once code generation starts, the Nexus structure no longer needs to
support fast insertion/connect operations. So have the code generator
lock down the Nexus structures and adjust the Link lists for optimal
access during readout.
When netlists get very large, the Nexus::connect() method tickles
the O(N) performance and elaboration gets very slow. Rework the
connect method to be O(C), for a drastic performance boost for
large designs.
This simplifies and reorganizes this function in order to improve
the performance of this function by a constant factor. I think we
really need to improve this by an entire order (and not just a
simple factor) but this helps.
It turns out that it is possible for an otherwise constant net
mux to be non-constant if there is a force that can drive the
net. This can be detected as an l-value reference to an otherwise
constant selector.
If a signed signal is driving a part select in a CA and the width
is less than 32 bits. the value will be zero extended and will
not work for negative values. This patch adds a warning that this
could happen. This will be fixed in development.
This patch is a major rewrite of the indexed part selects (+: and -:).
It made the following enhancements:
1. Make indexed part selects work correctly with both big and little
endian vectors.
2. Add a warning flag that warns about constant out of bounds/or 'bx
indexed selects.
3. Moved the -: parameter code to its own routine.
4. Added support for straddling before part selects in a CA.
5. Added more assert(! number_is_unknown) statements.
6. Add warning for &PV<> select with a signed index signal that is
less than the width of an int. This will be fixed later.
7. Add support for loading a 'bx/'bz constant into a numeric register.
8. Add a number of signed value fixes to the compiler/code generator.
9. Major fix of draw_select_expr() in the code generator.
This patch adds genvars to the elaboration process. It adds checks
that a genvar is defined for a generate loop and that a genvar does
not conflict with any other items in its name space.
This patch adds -g2001-noconfig command line flag. The compiler
already supported this with `begin_keywords. Document this in
the manual page and fix a few other issues.
Fix endgenerate to be a 2001 keyword and add a few missing
keywords at the appropriate standard level e.g.(unsigned).
Add uwire and deprecate wone. wone used to just convert without
a warning to a wire. uwire will display a warning that it is
being converted to a wire without a check. wone is converted to
a uwire with a warning and then prints the uwire message. The
uwire message will be replaced with a real check fairly soon.
This patch adds real functionality for `celldefine and pushes this
property to the run time which can access this with vpiCellInstance.
This is technically only available for a module, but all scopes
have the property and only modules should return true when the
'endmodule' is between a `celldefine and `endcelldefine directive.
In 1364-2005 it is an explicit error to take the select of a scalar
or real value. We added the checks for real a while ago. This patch
adds the functionality for scalar values. In the future we may want
to push the scalar property to the run time.
This patch add code to print a warning message if it finds both a
default and `timescale based delays. The -Wall or more specifically
the -Wtimescale flag can be used to find the module with the missing
`timescale directive.
The arithmetic operands are signed only if both operands are signed.
If the expression is unsigned, then the expression as a whole needs
to be processed as unsigned in order to get padding right.
When a pin array is virtual, dll_target::signal() doesn't need
to make a corresponding set of stub nexa.
This patch includes new detection of oversized arrays, configurable
with the ARRAY_SIZE_LIMIT flag. This limit only applies to devirtualized
arrays; virtual arrays are only limited by your architecture's
unsigned int type.
The concept and earlier versions of this patch have been successfully
stress-tested by multiple people. This one causes no testsuite
regressions on my machine.
Closes: pr2023076
Reduces resource usage when compiling large memories.
Normal usage patterns still create large nexus arrays
in t-dll.cc:dll_target::signal().
This patch is extensively tested; it shouldn't break anything.
The existing debug "optimizer" flag is (ab)used to control
message printing when large (>1000 element) arrays are
devirtualized or nexus-ized.
The new global variable disable_virtual_pins is available
to force allocation of Pin arrays when they are declared,
but no user interface is provided.
See extensive discussion on iverilog-devel, March 4-5 2009,
title "pr2023076: large memories".
This patch adds messages in various places to warn that constant
user functions are not supported. It uses a global variable to
indicate when we are in a constant context. This is a bit of a
kludge, but works well without needing to change a bunch of code.
It is interesting to note that ports are elaborated late enough
that if we had the constant function evaluation code they would
evaluate correctly. This also applies to the function return
range, the concatenation repeat, specparams and initial values.
Signal definitions are early enough that elaboration is what is
failing because the function body is not available (has not been
elaborated). The same thing applies to both parameters and
localparms.
Previously Icarus normalized the results so array [7:0] would
be the same as array [0:7]. This works just fine for
simulation, but the VPI calls can select the left or right
value and this was incorrect for the [7:0] case since it was
being normalized to [0:7]. This patch swaps the two values in
the a.out file and from this creates the previous first/last
values and a new flag that can be used to get the correct
left and right values for the VPI interface.
Seemingly does nothing, just refactors to create two new methods:
bool NetPins::is_linked(void)
void NetNet::initialize_value_and_dir(verinum::V init_value, Link::DIR dir)
and rearranges netlist.h.
This patch causes no regression in the testsuite.
It smooths the way for any attempt to address pr2023076.
By not creating Nexus objects until necessary, we avoid creating a
lot of spurious objects. In fact, it is true that almost every
link that is created and connected to another link will create a
spurious Nexus object without this patch.
Functions that appear in continuous assignment expressions and that
have hidden dependencies or side effects need to be re-evaluated
whenever any input to the expression changes. This patch adds support
in the compiler and vvp runtime to enable this. This is currently
activated for any system function call that has no arguments. The
user may also force it to be used for any user function by passing
the option -gstrict-ca-eval to the compiler driver.
This patch also removes the -dautomatic option which was used for
gaining confidence in the code that supports automatic tasks and
functions. It is believed that the testsuite provides reasonable
fault coverage, and further tests can be added if bugs are found.
This fixes up the elaboration of binary expressions found in
parameter expressions. Parameter expressions are special because
they elaborate early, before all the other parameters are necessarily
completed.
In the ivl_target API, the IVL_EX_BACCESS expression type gets some meat,
specifically references to the branch it accesses and the the nature to
be accessed on that branch.
This includes enough API to get the branch nexus bits and signals
and show them in the dump. This also includes creating the reference
ground for branch access functions that use the implicit ground.
This patch fixes a number of problems related to the divide and
modulus operators.
The net version (CA) of modulus did not support a signed version.
Division or modulus of a value wider than the machine word did
not correctly check for division by zero and return 'bx.
Fixed a problem in procedural modulus. The sign of the result is
only dependent on the L-value.
Division or modulus of a signed value that was the same width as
the machine word was creating an incorrect sign mask.
Division of a signed value that would fit into a single machine
word was not checking for division by zero.
Division or modulus of a wide value was always being done as
unsigned.
Added a negative operator for vvp_vector2_t. This made
implementing the signed wide division and modulus easier.
The natures of disciplines were already available, this just brings
the information forward to the ivl_target.h API and exposes them via
access functions.
The goal is to completely remove the svector class because the standard
vector class works perfectly well. This removes the uses in the Module.h
header file.
Signals may have VMA disciplines attached. Make the attached discipline
visible through the ivl_target.h API. Also, re-arrange the internal
handling of the discipline structure so that we can expose disciplines
through the ivl_target C API without creating new structures. The
t-dll-api implementations of the discipline access functions can look
at the elaborated discipline structure directly. This is possible since
the discipline parse and elaboration are very simple.
The arguments of logical and/or are self determined, and the width is
fixed as 1 bit. Account for this special behavior by creating the
PEBLogic class.
The comparison operator operands are self determined, but are forced
to be the width of the wider operand. This means that the operands must
be evaluated with their widths truncated. In spite of all this, note
that comparisons expression results are 1 bit wide.
Now that NetNet objects in NetScopes are kept in a map, remove the
linked list for scanning them. This improves the lookup process from
an O(e**N) process to more like O(log(N)). This matters for very
large designs.
Get at least basic elaboration of analog processes and contribution
statements. Bring the statements and analog statements together and
net future elaboration work sort out which statements are valid in
a given context. This makes sense because there really is a lot of
syntactic overlap, and analog behavioral code is processed somewhat
sequentially.
Put together the infrastructure for elaborating analog statements,
including create the NetAnalogTop objects that hold analog statements
and are in turn held by the design.
While doing this, clean up the various unique initial/always enumerations
to use the ivl_process_type_t type.
The signedness of comparison expressions is typically unsigned, even if
the comparison to be performed is signed. The comparison (and particularly
the expr_synth of the comparison) needs to account for this explicitly.
Start cleaning up shadowed variables, flagged by turning on -Wshadow.
No intended change in functionality. Patch looks right, and is tested
to compile and run on my machine. YMMV.
Widths of real values are always 1. When paired with vectorable types
in expressions, the vectorable type is processed as losslessly self-
determined. ("unsized" in the test_width methods.)
the PGAssign elaborate method used the test_width to get the width
of the r-value expression. This should be completely sufficient to
get the width of the expression, so always use a defined width to
elaborate the expression.
Remove redundant pointer to the containing NetPins object by keeping
the pointer only in the first Link (pin 0) of an array of links. In
this link, replace the pin number with the NetPins pointer, and set
a pins_zero_ flag to indicate that this has happened. This way, only
the first pin in a Link array will have the pointer to the NetPins
that contains the array, and the pointer takes up practically no space
at all.
This class was old, and its original design pulled literally from
the LPM reference. But of nine pins declared, only 4 were used.
Remove all the excess junk and clean up the designed dump handling
of the device.
The true and false expression clauses must have compatible types,
which are not necesarily identical. In particular, VT_BOOL and
VT_LOGIC are compatible for the purposes of ternary arguments. The
test in NetETernary::synthesize was incorrect.
In the process, fix the type handling of NetConst objects to allow
for IVL_VT_BOOL constants. This is information that the downstream
may find useful, so should be handled correctly.
This patch pushes the non-blocking event control information to
the code generator. It adds the %evctl statements that are used
to put the event control information into the special thread
event control registers. The signed version (%evctl/s) required
the implementation of %ix/getv/s to load a signed value into
an index register. It then adds %assign/wr/e event control based
non-blocking assignment for real values. It also fixes the other
non-blocking real assignments to use Transport instead of inertial
delays.
Nothing to do with tab width! Eliminates useless
trailing spaces and tabs, and nearly all <space><tab>
pairings. No change to derived files (e.g., .vvp),
non-master files (e.g., lxt2_write.c) or the new tgt-vhdl
directory.
Low priority, simple entropy reduction. Please apply
unless it deletes some steganographic content you want
to keep.
This patch moves the always zero or possibly zero delay checks
to a point after the circuit is full elaborated. Before it
could try to check tasks that had not already been evaluated
resulting in a crash.
This patch pushes the automatic property for both tasks and
functions to the code generators. The vvp back end does not
currently support this so it will error out during code
generation. The VHDL back end should be able to use this
property and tgt-stub prints the property. Having this will
also make it easier when we do adding this to the runtime.
This patch adds the $clog2 system function. It also makes this
function work as a constant function. The runtime version still
needs to be updated to use an integer based version instead of
the current double based method. The double method suffers from
rounding errors.
convert the continuous assign elaboration to use elaborate_expr
and synthesize methods instead of the elaborate_net methods of
PExpr. This exposes problems with the synthesize methods, but it
is a better way to do it.
In preparation for using the synthesize method to replace the
elaborate_net method of PExpr, rework the interface to the
synthesize() method. This changes no fnctionality, but does set
up the infrastructure for the next step.
When driving an input port to a module, watch out for the case where
the net is also driven within the instance. If this is the case, take
pains to make sure what goes on in the instance doesn't leak out
through the input port. Add a BUFZ (continuous assignment) to isolate
the context from internal driving.
The NetBranch object is connected, but not like an object, so the
NetPins object base class is factored out from NetObj to handle the
connectivity, and the NetBranch class uses the NetPins to connect a
branch.
Also, account for the fact that nets with a discipline are by default
real-valued.
Detect function call expressions that turn out to be calls to the
access function of a nature. Elaborate the access function and stub
the emit code. This gets the access function just short of the code
generator.
When generate schems and instance arrays are nested, it takes
multiple iterations of elaborate scope, defparams and evaluate
parameters before everything is worked out. Rework the work item
processing so that the loop elaborates scopes and runs defparams
in phases. The phases are needed so that we can tell when the
remaining defparams are orphaned.
It is possible for defparams to not find their target the first time
around, because the elaboration of the target scope is not yet done.
So retry the defparams once for each scope by putting it on a work
item in the elaborator_work_items list.
Putting scope elaboration into work queue items allows for handling
more complex processing order. The elaboration_work_list queue drives
the processing of elaborate_scope and parameter evaluation.
This patch adds .cast/int and updates .cast/real to act as a local
(temporary) net and to support either a signed or unsigned input.
The vvp_vector4_t class not can convert an arbitrarily sized double
to a vector value. This removes the restriction of lround().
Also document the new statements.
This handles the general case of a non-real operand to a real-valued
division. This can turn up if only 1 operand of a divide is real. In
this case the division as a whole is real and the other operand must
be cast to real.
This method creates an extra node, but it should be a very compact
node and this node does no evaluation tricks so in the run time should
be no more expensive then folding the cast into the .arith/div.r itself.
Rather then join islands while branches are initially created, save the
island creating for the end. This way, the process is actually recursive
and greedy, reliably collecting branches into islands without conflict.
Fold the bi-directional part select into the pass switch (tran) support
so that it can be really bi-directional. This involves adding a new
tranvp device that does part select in tran islands, and reworking the
tran island resolution to handle non-identical nodes. This will be needed
for resistive tran devices anyhow.
NetTran devices must be collected into islands because they are all
a bi-directional mass. This is how vvp will process them and the code
generator will need a head start organizing them.
This involves defining the API for switches and cleaning up the
elaborated form to match the defined ivl_target API. Also add t-dll
code to support the ivl_switch_t functions, and add stub code that
checks the results.
The tran devices include tran, rtran, tranif0/1 and rtranif0/1. These
are all elaborated as options on a NetTran device. It is still not
clear the best way to present tran devices via the ivl_target.h API.
Before this, the types of parameters were always logic, only the
width and signed-ness could be controlled. A parameter may take
on implicit real values if the expression were real.
With this patch, the type for the parameter can be explicitly set
to logic or real. This also means that the parameter real valued
expressions need to be more crefully treated, possibly with casting
integral expressions to real values, or real expressions to integral
values.
The pform is now translated/elaborated into NetScope objects. All that
remains is to check the parameter values against the ranges. This is
to be done in the evaluate_parameters() method.
The Verilog LRM specifies that it is legal to give constant part
selects that are beyond the bounds of the identifier being selected.
But elaboration was flagging that as an error. This patch changes it
to a warning, and handles the cases by generating 'bx bits as needed.
This patch adds file and line information for parameters and
local parameters. It also adds file/line stubs for signals in
the tgt-* files. It adds the pform code needed to eventually
do genvar checks and passing of genvar file/line information.
It verifies that a genvar does not have the same name as a
parameter/local parameter.
In continuous assign expressions, the abs() operator can't easily be
burried in generic unary handling, so add the IVL_LPM_ABS type and
generate it as needed.
Implement in behavioral the abs/min/max operators for real values.
The parser treats these builtin functions as operators, unary or
binary, and elaborates them appropriately.
Also add enough code generator support to handle real valued expressions
in thread context.
This patch adds code to push the file and line information
for scope objects (modules, functions, tasks, etc.) to the
runtime. For modules, this includes the definition fields.
This patch adds ifnone functionality. It does not produce an
error when both an ifnone and an unconditional simple module
path are given. For this case the ifnone delays are ignored.
This patch adds check to determine if an always block has delay
in it or not. If there is no delay a runtime infinite loop will
occur. For the indeterminate case it will print a warning message
if the new -Winfloop flag is given. This flag is not part of the
-Wall check!
This patch reworks much of the ternary code to short circuit when
possible and supports real values better. It adds a blend operator
for real values that returns 0.0 when the values differ and the value
when they match. This deviates slightly from the standard which
specifies that the value for reals is always 0.0 when the conditional
is 'bx. There are also a couple bug fixes.
These fixes have not been ported to continuous assignments yet.
Ternary operators used at compile time and in procedural assignments
should be complete (short circuit and support real values).
Case-generate alternatives create sub-scopes that need to be scanned
by the scope scanner in order to get function definitions etc. that
are defined lexically within generated scopes.
Move the storage of wires (signals) out of the Module class into
the PScope base class, and instead of putting the PWires all into
the Module object, distribute them into the various lexical scopes
(derived from PScope) so that the wire names do not need to carry
scope information.
This required some rewiring of elaboration of signals, and rewriting
of lexical scope handling.
Padding and continuous assignment caused problems if the continuous
assignment includes a delay. The problem is that the padding was
not necessarily included in the delay. Rework the elaboration to
make sure the padding is indeed included in the delay.
Allow user defined functions to take real value arguments and return
real value results in net contexts. Use the data type of the nets
attached to the ports to define the data types of the arguments and
return value.
There was much redundant code in the compile-tile handling of the
less-then and greater-then of constant expressions, and much of it
was buggy. Unify much of the code and squeeze out the bugs so that
compile-time evaluations come out correctly.
In nets, if system functions return a real value the function lookup
was getting the correct width, but was also setting the width to 0,
which confused down-stream net handling. Real-value system fuctions
have a width of 1. (1 real-valued scalar.)
When evaluating bitwise binary expressions at compile time, get the
signed/unsigned padding correct. Pay special attention to the case
of $signed/$unsigned changing the signedness of the operand.
This patch causes unnamed generate blocks to be automatically named
using the naming scheme defined in the Verilog-2005 standard. This
is a fix for the problem discussed in pr1821610.
@* was only expanding to input nets. nex_input() for blocks was removing
any output net that was also an input. There was also a bug in how output
nets were removed. Only outputs currently defined were removed from the
input list.
always @(*) begin
y = a;
z = y;
end
would report "a" as an input. While
always @(*) begin
z = y;
y = a;
end
would report both "a" and "y" as inputs.
To fix this all nex_inputs now take a flag that when true (the default)
correctly removes any output from the input list. Both the above cases
will now return "a". If the flag is false outputs which are also inputs
will be included in the input list. This is what the @* elaboration code
uses to get the correct sensitivity list.
This patch adds checks to verify that functions do not invoke
statements that are invalid for them (#, @, wait, enable/call
tasks and non blocking assignment). For reference see section
10.3.4 of 1364-2001.
distinguish between self-determined and value-preserving when
evaluating constants that are arguments to concatenations.
Signed-off-by: Stephen Williams <steve@icarus.com>
more general concept of arrays. The NetMemory and NetEMemory
classes are removed from the ivl core program, and the IVL_LPM_RAM
lpm type is removed from the ivl_target API.
including assing, cassign and force.
Generate NetConcat devices for gate outputs that feed into a
vector results. Use this to hande gate arrays. Also let gate
arrays handle vectors of gates when the outputs allow for it.
Stephen Williams
Cary R
Larry Doolittle
Martin Whitaker
steve