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Add warning for poor activities convergence #118

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Add warning for poor activities convergence #118

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1 change: 1 addition & 0 deletions doc/messages.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,7 @@
1060 Genclks.cc:275 no master clock found for generated clock %s.
1062 Genclks.cc:939 generated clock %s source pin %s missing paths from master clock %s.
1100 Power.cc:556 unknown cudd constant
1101 Power.cc:651 poor convergence of propagated activities for power estimation after %d passes
1110 Liberty.cc:763 cell %s/%s port %s not found in cell %s/%s.
1111 Liberty.cc:789 cell %s/%s %s -> %s timing group %s not found in cell %s/%s.
1112 Liberty.cc:808 Liberty cell %s/%s for corner %s/%s not found.
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38 changes: 22 additions & 16 deletions power/Power.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -629,22 +629,28 @@ Power::ensureActivities()
bfs.visit(levelize_->maxLevel(), &visitor);
// Propagate activiities through registers.
InstanceSet regs = std::move(visitor.visitedRegs());
int pass = 1;
while (!regs.empty() && pass < max_activity_passes_) {
visitor.init();
InstanceSet::Iterator reg_iter(regs);
while (reg_iter.hasNext()) {
const Instance *reg = reg_iter.next();
// Propagate activiities across register D->Q.
seedRegOutputActivities(reg, bfs);
}
// Propagate register output activities through
// combinational logic.
bfs.visit(levelize_->maxLevel(), &visitor);
regs = std::move(visitor.visitedRegs());
debugPrint(debug_, "power_activity", 1, "Pass %d change %.2f",
pass, visitor.maxChange());
pass++;
if (!regs.empty()) {
int pass = 1;
while (!regs.empty() && pass < max_activity_passes_) {
visitor.init();
InstanceSet::Iterator reg_iter(regs);
while (reg_iter.hasNext()) {
const Instance *reg = reg_iter.next();
// Propagate activiities across register D->Q.
seedRegOutputActivities(reg, bfs);
}
// Propagate register output activities through
// combinational logic.
bfs.visit(levelize_->maxLevel(), &visitor);
regs = std::move(visitor.visitedRegs());
debugPrint(debug_, "power_activity", 1, "Pass %d change %.2f",
pass, visitor.maxChange());
pass++;
}
if (visitor.maxChange() > 0.20) {
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This warns for nearly every power regression I have even though the activities indeed do converge. Consider a circuit with no feedback. When the activities propagate on the first pass they change by whatever the input activity is (with may be > .2). Since there is no feedback they are not re-queued and regs is empty. The activities are converged but it still warns about non-convergence. I think the true criteria for non-convergence is "pass == max_activity_passes_". All of the opensta regressions I have converge, so maybe the place to start is to make a test case and submit it as an issue.

report_->warn(1101, "poor convergence of propagated activities for power estimation after %d passes",
max_activity_passes_);
}
}
activities_valid_ = true;
}
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