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Fix unrolling complicated for-loop bounds, bug677.

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Signed-off-by: Wilson Snyder <wsnyder@wsnyder.org>
This commit is contained in:
Johan Bjork 2016-01-21 19:00:19 -05:00 committed by Wilson Snyder
parent e061eb3003
commit 63f111b7f3
5 changed files with 218 additions and 125 deletions
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2
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@ -7,6 +7,8 @@ indicates the contributor was also the author of the fix; Thanks!
**** Internal Verilation-time performance enhancements, bug1021. [Johan Bjork]
**** Fix unrolling complicated for-loop bounds, bug677. [Johan Bjork]
**** Fix stats file containing multiple unroll entries, bug1020. [Johan Bjork]
**** Fix using short parameter names on negative params, bug1022. [Duraid Madina]

6
src/V3Simulate.h
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@ -831,7 +831,7 @@ public:
// Move all allocated numbers to the free pool
m_numFreeps = m_numAllps;
}
void mainTableCheck (AstNode* nodep) {
void mainTableCheck (AstNode* nodep) {
setMode(true/*scoped*/,true/*checking*/, false/*params*/);
mainGuts(nodep);
}
@ -839,6 +839,10 @@ public:
setMode(true/*scoped*/,false/*checking*/, false/*params*/);
mainGuts(nodep);
}
void mainCheckTree (AstNode* nodep) {
setMode(false/*scoped*/,true/*checking*/, false/*params*/);
mainGuts(nodep);
}
void mainParamEmulate (AstNode* nodep) {
setMode(false/*scoped*/,false/*checking*/, true/*params*/);
mainGuts(nodep);

273
src/V3Unroll.cpp
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@ -40,6 +40,7 @@
#include "V3Stats.h"
#include "V3Const.h"
#include "V3Ast.h"
#include "V3Simulate.h"
//######################################################################
// Unroll state, as a visitor of each AstNode
@ -107,19 +108,12 @@ private:
if (precondsp) UINFO(6, " Pcon "<<precondsp<<endl);
if (condp) UINFO(6, " Cond "<<condp<<endl);
if (incp) UINFO(6, " Inc "<<incp<<endl);
// Initial value check
AstAssign* initAssp = initp->castAssign();
if (!initAssp) return cantUnroll(nodep, "no initial assignment");
if (initp->nextp() && initp->nextp()!=nodep) nodep->v3fatalSrc("initial assignment shouldn't be a list");
if (!initAssp->lhsp()->castVarRef()) return cantUnroll(nodep, "no initial assignment to simple variable");
m_forVarp = initAssp->lhsp()->castVarRef()->varp();
m_forVscp = initAssp->lhsp()->castVarRef()->varScopep();
if (nodep->castGenFor() && !m_forVarp->isGenVar()) {
nodep->v3error("Non-genvar used in generate for: "<<m_forVarp->prettyName()<<endl);
}
if (m_generate) V3Const::constifyParamsEdit(initAssp->rhsp()); // rhsp may change
AstConst* constInitp = initAssp->rhsp()->castConst();
if (!constInitp) return cantUnroll(nodep, "non-constant initializer");
//
// Condition check
if (condp->nextp()) nodep->v3fatalSrc("conditional shouldn't be a list");
@ -128,93 +122,21 @@ private:
AstAssign* incAssp = incp->castAssign();
if (!incAssp) return cantUnroll(nodep, "no increment assignment");
if (incAssp->nextp()) nodep->v3fatalSrc("increment shouldn't be a list");
AstNodeBiop* incInstrp = incAssp->rhsp()->castNodeBiop();
//
if (m_forVscp) { UINFO(8, " Loop Variable: "<<m_forVscp<<endl); }
else { UINFO(8, " Loop Variable: "<<m_forVarp<<endl); }
if (debug()>=9) nodep->dumpTree(cout,"- for: ");
//
// Extract the constant loop bounds
bool subtract = incInstrp->castSub();
{
if (!subtract && !incInstrp->castAdd()) return cantUnroll(nodep, "missing add/sub for incrementer");
AstVarRef* incVarrp = (subtract ? incInstrp->lhsp()->castVarRef()
: incInstrp->rhsp()->castVarRef());
if (!incVarrp) return cantUnroll(nodep, "missing variable in incrementer");
if (incVarrp->varp() != m_forVarp
|| incVarrp->varScopep() != m_forVscp) {
return cantUnroll(nodep, "different variables in incrementer");
}
}
//
// Adds have the # on the lhsp because V3Const pushes rhs consts over to the lhs
// Subtracts have it on the rhs, because you write i=i-1; i=1-i is non-sensible.
AstConst* preconstIncp = (subtract ? incInstrp->rhsp()->castConst()
: incInstrp->lhsp()->castConst());
if (m_generate) preconstIncp = V3Const::constifyParamsEdit(preconstIncp)->castConst();
AstConst* constIncp = (subtract ? incInstrp->rhsp()->castConst()
: incInstrp->lhsp()->castConst());
UINFO(8, " Inc expr ok: "<<constIncp<<endl);
if (!constIncp) return cantUnroll(nodep, "non-constant increment");
if (constIncp->isZero()) return cantUnroll(nodep, "zero increment"); // Or we could loop forever below...
bool lt = condp->castLt() || condp->castLtS();
bool lte = condp->castLte() || condp->castLteS();
bool gt = condp->castGt() || condp->castGtS();
bool gte = condp->castGte() || condp->castGteS();
if (!lt && !lte && !gt && !gte)
return cantUnroll(nodep, "condition not <=, <, >= or >");
AstNodeBiop* cmpInstrp = condp->castNodeBiop();
bool cmpVarLhs;
if (cmpInstrp->lhsp()->castVarRef()
&& cmpInstrp->lhsp()->castVarRef()->varp() == m_forVarp
&& cmpInstrp->lhsp()->castVarRef()->varScopep() == m_forVscp) {
cmpVarLhs = true;
} else if (cmpInstrp->rhsp()->castVarRef()
&& cmpInstrp->rhsp()->castVarRef()->varp() == m_forVarp
&& cmpInstrp->rhsp()->castVarRef()->varScopep() == m_forVscp) {
cmpVarLhs = false;
} else if (!cmpInstrp->rhsp()->castVarRef()) {
return cantUnroll(nodep, "no variable on rhs of condition");
} else {
return cantUnroll(nodep, "different variable in condition");
m_forVarp = initAssp->lhsp()->castVarRef()->varp();
m_forVscp = initAssp->lhsp()->castVarRef()->varScopep();
if (nodep->castGenFor() && !m_forVarp->isGenVar()) {
nodep->v3error("Non-genvar used in generate for: "<<m_forVarp->prettyName()<<endl);
}
if (m_generate) V3Const::constifyParamsEdit(initAssp->rhsp()); // rhsp may change
if (m_generate) V3Const::constifyParamsEdit(cmpVarLhs ? cmpInstrp->rhsp()
: cmpInstrp->lhsp()); // rhsp/lhsp may change
AstConst* constStopp = (cmpVarLhs ? cmpInstrp->rhsp()->castConst()
: cmpInstrp->lhsp()->castConst());
if (!constStopp) return cantUnroll(nodep, "non-constant final value");
UINFO(8, " Stop expr ok: "<<constStopp<<endl);
//
if (constInitp->width()>32 || constInitp->num().isFourState()
|| constStopp->width()>32 || constStopp->num().isFourState()
|| constIncp->width()>32 || constIncp->num().isFourState())
return cantUnroll(nodep, "init/final/increment too large or four state");
vlsint32_t valInit = constInitp->num().toSInt();
vlsint32_t valStop = constStopp->num().toSInt();
if (gte) valStop++; if (lte) valStop--; // 23 >= a, handle as if 24 > a
vlsint32_t valInc = constIncp->num().toSInt();
if (subtract) valInc = -valInc;
UINFO(8," In Numbers: for (v="<<valInit<<"; v<"<<valStop<<"; v=v+"<<valInc<<")\n");
//
if (!m_generate) {
int loops = ((valStop - valInit)/valInc);
if (loops < 0) { loops += (1ULL<<constStopp->width()); } // Will roll around
UINFO(8, " ~Iters: "<<loops<<" c="<<unrollCount()<<endl);
if (loops > unrollCount())
return cantUnroll(nodep, "too many iterations");
// This check shouldn't be needed when using V3Simulate
// however, for repeat loops, the loop variable is auto-generated
// and the initp statements will reference a variable outside of the initp scope
// alas, failing to simulate.
AstConst* constInitp = initAssp->rhsp()->castConst();
if (!constInitp) return cantUnroll(nodep, "non-constant initializer");
// Less than 10 statements in the body?
int bodySize = 0;
int bodyLimit = v3Global.opt.unrollStmts();
if (loops>0) bodyLimit = v3Global.opt.unrollStmts() / loops;
if (bodySizeOverRecurse(precondsp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(bodysp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(incp, bodySize/*ref*/, bodyLimit)) {
return cantUnroll(nodep, "too many statements");
}
}
//
// Now, make sure there's no assignment to this variable in the loop
m_varModeCheck = true;
@ -226,26 +148,131 @@ private:
m_varModeCheck = false;
m_ignoreIncp = NULL;
if (m_varAssignHit) return cantUnroll(nodep, "genvar assigned *inside* loop");
//
if (m_forVscp) { UINFO(8, " Loop Variable: "<<m_forVscp<<endl); }
else { UINFO(8, " Loop Variable: "<<m_forVarp<<endl); }
if (debug()>=9) nodep->dumpTree(cout,"- for: ");
if (!m_generate) {
AstAssign *incpAssign = incp->castAssign();
if (!canSimulate(incpAssign->rhsp())) return cantUnroll(incp, "Unable to simulate increment");
if (!canSimulate(condp)) return cantUnroll(condp, "Unable to simulate condition");
// Check whether to we actually want to try and unroll.
int loops;
if (!countLoops(initAssp, condp, incp, unrollCount(), loops))
return cantUnroll(nodep, "Unable to simulate loop");
// Less than 10 statements in the body?
int bodySize = 0;
int bodyLimit = v3Global.opt.unrollStmts();
if (loops>0) bodyLimit = v3Global.opt.unrollStmts() / loops;
if (bodySizeOverRecurse(precondsp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(bodysp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(incp, bodySize/*ref*/, bodyLimit)) {
return cantUnroll(nodep, "too many statements");
}
}
// Finally, we can do it
forUnroller(nodep, initp, precondsp, incp, bodysp,
constInitp->num(),
cmpInstrp, constStopp->num(), cmpVarLhs,
incInstrp, constIncp->num()); VL_DANGLING(nodep);
if (!forUnroller(nodep, initAssp, condp, precondsp, incp, bodysp)) {
return cantUnroll(nodep, "Unable to unroll loop");
}
VL_DANGLING(nodep);
// Cleanup
return true;
}
void forUnroller(AstNode* nodep,
AstNode* initp,
bool canSimulate(AstNode *nodep) {
SimulateVisitor simvis;
AstNode* clone = nodep->cloneTree(true);
simvis.mainCheckTree(clone);
return simvis.optimizable();
}
bool simulateTree(AstNode *nodep, const V3Number *loopValue, AstNode *dtypep, V3Number &outNum) {
AstNode* clone = nodep->cloneTree(true);
if (!clone) {
nodep->v3fatalSrc("Failed to clone tree");
return false;
}
if (loopValue) {
m_varValuep = new AstConst (nodep->fileline(), *loopValue);
// Iteration requires a back, so put under temporary node
AstBegin* tempp = new AstBegin (nodep->fileline(), "[EditWrapper]", clone);
m_varModeReplace = true;
tempp->stmtsp()->iterateAndNext(*this);
m_varModeReplace = false;
clone = tempp->stmtsp()->unlinkFrBackWithNext();
tempp->deleteTree();
tempp = NULL;
pushDeletep(m_varValuep); m_varValuep = NULL;
}
SimulateVisitor simvis;
simvis.mainParamEmulate(clone);
if (!simvis.optimizable()) {
UINFO(3, "Unable to simulate" << endl);
if (debug()>=9) nodep->dumpTree(cout,"- _simtree: ");
return false;
}
// Fetch the result
V3Number* res = simvis.fetchNumberNull(clone);
if (!res) {
UINFO(3, "No number returned from simulation" << endl);
return false;
}
// Patch up datatype
if (dtypep) {
AstConst new_con (clone->fileline(), *res);
new_con.dtypeFrom(dtypep);
outNum = new_con.num();
return true;
}
outNum = *res;
return true;
}
bool countLoops(AstAssign *initp, AstNode *condp, AstNode *incp, int max, int &outLoopsr) {
outLoopsr = 0;
V3Number loopValue = V3Number(initp->fileline());
if (!simulateTree(initp->rhsp(), NULL, initp, loopValue)) {
return false;
}
while (1) {
V3Number res = V3Number(initp->fileline());
if (!simulateTree(condp, &loopValue, NULL, res)) {
return false;
}
if (!res.isEqOne()) {
break;
}
outLoopsr++;
// Run inc
AstAssign* incpass = incp->castAssign();
V3Number newLoopValue = V3Number(initp->fileline());
if (!simulateTree(incpass->rhsp(), &loopValue, incpass, newLoopValue)) {
return false;
}
loopValue.opAssign(newLoopValue);
if (outLoopsr > max) {
return false;
}
}
return true;
}
bool forUnroller(AstNode* nodep,
AstAssign* initp,
AstNode* condp,
AstNode* precondsp,
AstNode* incp, AstNode* bodysp,
const V3Number& numInit,
AstNodeBiop* cmpInstrp, const V3Number& numStop, bool cmpVarLhs,
AstNodeBiop* incInstrp, const V3Number& numInc) {
UINFO(4, " Unroll for var="<<numInit<<"; var<"<<numStop<<"; var+="<<numInc<<endl);
UINFO(6, " cmpI "<<cmpInstrp<<endl);
UINFO(6, " IncI "<<incInstrp<<endl);
AstNode* incp, AstNode* bodysp) {
V3Number loopValue = V3Number(nodep->fileline());
if (!simulateTree(initp->rhsp(), NULL, initp, loopValue)) {
return false;
}
AstNode* stmtsp = NULL;
if (initp) {
initp->unlinkFrBack(); // Always a single statement; nextp() may be nodep
@ -269,26 +296,21 @@ private:
// Mark variable to disable some later warnings
m_forVarp->usedLoopIdx(true);
// If it's a While, then incp is already part of bodysp.
V3Number loopValue(nodep->fileline(), m_forVarp->width()); // May differ in size from numInitp
loopValue.opAssign(numInit);
AstNode* newbodysp = NULL;
++m_statLoops;
if (stmtsp) {
int times = 0;
while (1) {
UINFO(8," Looping "<<loopValue<<endl);
// if loopValue<valStop
V3Number contin (nodep->fileline(), 1);
if (cmpVarLhs) {
cmpInstrp->numberOperate(contin, loopValue, numStop);
} else {
cmpInstrp->numberOperate(contin, numStop, loopValue);
V3Number res = V3Number(nodep->fileline());
if (!simulateTree(condp, &loopValue, NULL, res)) {
nodep->v3error("Loop unrolling failed.");
return false;
}
if (contin.isEqZero()) {
if (!res.isEqOne()) {
break; // Done with the loop
} else {
}
else {
// Replace iterator values with constant.
AstNode* oneloopp = stmtsp->cloneTree(true);
@ -307,7 +329,7 @@ private:
string nname = m_beginName + "__BRA__" + index + "__KET__";
oneloopp = new AstBegin(oneloopp->fileline(),nname,oneloopp,true);
}
pushDeletep(m_varValuep); m_varValuep=NULL;
if (newbodysp) newbodysp->addNext(oneloopp);
else newbodysp = oneloopp;
@ -317,12 +339,14 @@ private:
break;
}
//loopValue += valInc
V3Number newnum(nodep->fileline(), m_forVarp->width()); // Can't increment in-place
incInstrp->numberOperate(newnum, loopValue, numInc);
loopValue.opAssign(newnum);
pushDeletep(m_varValuep); m_varValuep=NULL;
// loopValue += valInc
AstAssign *incpass = incp->castAssign();
V3Number newLoopValue = V3Number(nodep->fileline());
if (!simulateTree(incpass->rhsp(), &loopValue, incpass, newLoopValue)) {
nodep->v3error("Loop unrolling failed");
return false;
}
loopValue.opAssign(newLoopValue);
}
}
}
@ -334,6 +358,7 @@ private:
if (initp) { pushDeletep(initp); VL_DANGLING(initp); }
if (incp && !incp->backp()) { pushDeletep(incp); VL_DANGLING(incp); }
if (debug()>=9) newbodysp->dumpTree(cout,"- _new: ");
return true;
}
virtual void visit(AstWhile* nodep, AstNUser*) {
@ -342,7 +367,7 @@ private:
} else {
// Constify before unroll call, as it may change what is underneath.
if (nodep->precondsp()) V3Const::constifyEdit(nodep->precondsp()); // precondsp may change
if (nodep->condp()) V3Const::constifyEdit(nodep->condp()); //condp may change
if (nodep->condp()) V3Const::constifyEdit(nodep->condp()); // condp may change
// Grab initial value
AstNode* initp = NULL; // Should be statement before the while.
if (nodep->backp()->nextp() == nodep) initp=nodep->backp();

18
test_regress/t/t_unroll_complexcond.pl Executable file
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@ -0,0 +1,18 @@
#!/usr/bin/perl
if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
# DESCRIPTION: Verilator: Verilog Test driver/expect definition
#
# Copyright 2003 by Wilson Snyder. This program is free software; you can
# redistribute it and/or modify it under the terms of either the GNU
# Lesser General Public License Version 3 or the Perl Artistic License
# Version 2.0.
compile (
);
execute (
check_finished=>1,
);
ok(1);
1;

44
test_regress/t/t_unroll_complexcond.v Normal file
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@ -0,0 +1,44 @@
// DESCRIPTION: Verilator: Verilog Test module
//
// This files is used to generated the BLKLOOPINIT error which
// is actually caused by not being able to unroll the for loop.
//
//
// This file ONLY is placed into the Public Domain, for any use,
// without warranty, 2013 by Jie Xu.
module t (/*AUTOARG*/
// Inputs
clk
);
input clk;
reg [3:0] tmp [3:0];
initial begin
tmp[0] = 4'b0000;
tmp[2] = 4'b0010;
tmp[3] = 4'b0011;
end
// Test loop
always @ (posedge clk) begin
int i;
int j;
for (i = 0;(i < 4) && (i > 1); i++) begin
tmp[i] <= tmp[i-i];
end
if (tmp[0] != 4'b0000) $stop;
if (tmp[3] != 4'b0011) $stop;
j = 0; for (i=$c32("1"); i<3; ++i) j++;
if (j!=2) $stop;
j = 0; for (i=1; i<$c32("3"); ++i) j++;
if (j!=2) $stop;
j = 0; for (i=1; i<3; i=i+$c32("1")) j++;
if (j!=2) $stop;
$write("*-* All Finished *-*\n");
$finish;
end
endmodule