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wasm-reduce: reduce switch targets #1752

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Merged
kripken merged 2 commits into from
Nov 16, 2018
Merged

wasm-reduce: reduce switch targets #1752

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424f335
reduce switch targets
kripken Nov 16, 2018
b827aa7
use pop/push
kripken Nov 16, 2018
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23 changes: 21 additions & 2 deletions src/tools/wasm-reduce.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -429,6 +429,25 @@ struct Reducer : public WalkerPass<PostWalker<Reducer, UnifiedExpressionVisitor<
handleCondition(select->condition);
} else if (auto* sw = curr->dynCast<Switch>()) {
handleCondition(sw->condition);
// Try to replace switch targets with the default
for (auto& target : sw->targets) {
if (target != sw->default_) {
auto old = target;
target = sw->default_;
if (!tryToReplaceCurrent(curr)) {
target = old;
}
}
}
// Try to shorten the list of targets.
while (sw->targets.size() > 1) {
auto last = sw->targets.back();
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@dschuff dschuff Nov 16, 2018

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can this just be pop_back()?

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@kripken kripken Nov 16, 2018

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Good idea, fixed. Found a few more in this file too.

(Honestly beceause pop_back() doesn't return a value I think I just gave up and forgot about it...)

sw->targets.pop_back();
if (!tryToReplaceCurrent(curr)) {
sw->targets.push_back(last);
break;
}
}
} else if (auto* block = curr->dynCast<Block>()) {
if (!shouldTryToReduce()) return;
// replace a singleton
Expand All @@ -445,13 +464,13 @@ struct Reducer : public WalkerPass<PostWalker<Reducer, UnifiedExpressionVisitor<
for (Index j = i; j < list.size() - 1; j++) {
list[j] = list[j + 1];
}
list.resize(list.size() - 1);
list.pop_back();
if (writeAndTestReduction()) {
std::cerr << "| block-nop removed\n";
noteReduction();
return;
}
list.resize(list.size() + 1);
list.push_back(nullptr);
// we failed; undo
for (Index j = list.size() - 1; j > i; j--) {
list[j] = list[j - 1];
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