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Add unroll_disable and unroll_full loop control metacomments (#3260).

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This commit is contained in:
Wilson Snyder
2024-01-26 07:49:07 -05:00
parent 94460867d3
commit d6f8ccd20b
19 changed files with 241 additions and 45 deletions
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src/V3Unroll.cpp
+27 -24
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@@ -47,7 +47,6 @@ class UnrollVisitor final : public VNVisitor {
bool m_varModeReplace; // Replacing varrefs
bool m_varAssignHit; // Assign var hit
bool m_generate; // Expand single generate For loop
int m_unrollLimit; // Unrolling limit
string m_beginName; // What name to give begin iterations
VDouble0 m_statLoops; // Statistic tracking
VDouble0 m_statIters; // Statistic tracking
@@ -80,6 +79,7 @@ class UnrollVisitor final : public VNVisitor {
bool forUnrollCheck(
AstNode* const nodep,
const VOptionBool& unrollFull, // Pragma unroll_full, unroll_disable
AstNode* const initp, // Maybe under nodep (no nextp), or standalone (ignore nextp)
AstNode* const precondsp, AstNode* condp,
AstNode* const incp, // Maybe under nodep or in bodysp
@@ -91,6 +91,8 @@ class UnrollVisitor final : public VNVisitor {
if (condp) UINFO(6, " Cond " << condp << endl);
if (incp) UINFO(6, " Inc " << incp << endl);
if (unrollFull.isSetFalse()) return cantUnroll(nodep, "pragma unroll_disable");
// Initial value check
AstAssign* const initAssp = VN_CAST(initp, Assign);
if (!initAssp) return cantUnroll(nodep, "no initial assignment");
@@ -156,22 +158,25 @@ class UnrollVisitor final : public VNVisitor {
// Check whether to we actually want to try and unroll.
int loops;
if (!countLoops(initAssp, condp, incp, m_unrollLimit, loops)) {
const int limit = v3Global.opt.unrollCountAdjusted(unrollFull, m_generate, false);
if (!countLoops(initAssp, condp, incp, limit, 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");
if (!unrollFull.isSetTrue()) {
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
if (!forUnroller(nodep, initAssp, condp, precondsp, incp, bodysp)) {
if (!forUnroller(nodep, unrollFull, initAssp, condp, precondsp, incp, bodysp)) {
return cantUnroll(nodep, "Unable to unroll loop");
}
VL_DANGLING(nodep);
@@ -259,8 +264,8 @@ class UnrollVisitor final : public VNVisitor {
return true;
}
bool forUnroller(AstNode* nodep, AstAssign* initp, AstNode* condp, AstNode* precondsp,
AstNode* incp, AstNode* bodysp) {
bool forUnroller(AstNode* nodep, const VOptionBool& unrollFull, AstAssign* initp,
AstNode* condp, AstNode* precondsp, AstNode* incp, AstNode* bodysp) {
UINFO(9, "forUnroller " << nodep << endl);
V3Number loopValue{nodep};
if (!simulateTree(initp->rhsp(), nullptr, initp, loopValue)) { //
@@ -329,11 +334,14 @@ class UnrollVisitor final : public VNVisitor {
}
++m_statIters;
if (++times / 3 > m_unrollLimit) {
const int limit
= v3Global.opt.unrollCountAdjusted(unrollFull, m_generate, false);
if (++times / 3 > limit) {
nodep->v3error(
"Loop unrolling took too long;"
" probably this is an infinite loop, or set --unroll-count above "
<< m_unrollLimit);
" probably this is an infinite loop, "
" or use /*verilator unroll_full*/, or set --unroll-count above "
<< times);
break;
}
@@ -396,7 +404,8 @@ class UnrollVisitor final : public VNVisitor {
if (incp == stmtsp) stmtsp = nullptr;
}
// And check it
if (forUnrollCheck(nodep, initp, nodep->precondsp(), nodep->condp(), incp, stmtsp)) {
if (forUnrollCheck(nodep, nodep->unrollFull(), initp, nodep->precondsp(),
nodep->condp(), incp, stmtsp)) {
VL_DO_DANGLING(pushDeletep(nodep), nodep); // Did replacement
}
}
@@ -420,8 +429,8 @@ class UnrollVisitor final : public VNVisitor {
// condition, but they'll become while's which can be
// deleted by V3Const.
VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
} else if (forUnrollCheck(nodep, nodep->initsp(), nullptr, nodep->condp(),
nodep->incsp(), nodep->stmtsp())) {
} else if (forUnrollCheck(nodep, VOptionBool{}, nodep->initsp(), nullptr,
nodep->condp(), nodep->incsp(), nodep->stmtsp())) {
VL_DO_DANGLING(pushDeletep(nodep), nodep); // Did replacement
} else {
nodep->v3error("For loop doesn't have genvar index, or is malformed");
@@ -478,12 +487,6 @@ public:
m_varModeReplace = false;
m_varAssignHit = false;
m_generate = generate;
m_unrollLimit = v3Global.opt.unrollCount();
if (generate) {
m_unrollLimit = std::numeric_limits<int>::max() / 16 > m_unrollLimit
? m_unrollLimit * 16
: std::numeric_limits<int>::max();
}
m_beginName = beginName;
}
void process(AstNode* nodep, bool generate, const string& beginName) {