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-rw-r--r--src/passes/RemoveUnusedBrs.cpp52
-rw-r--r--src/passes/SimplifyLocals.cpp85
2 files changed, 115 insertions, 22 deletions
diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index 9f753024d..c8c2277dc 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -276,6 +276,8 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
}
}
// TODO: if-else can be turned into a br_if as well, if one of the sides is a dead end
+ // we handle the case of a returned value to a set_local later down, see
+ // visitSetLocal.
}
// override scan to add a pre and a post check task to all nodes
@@ -661,6 +663,56 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
}
}
+ void visitSetLocal(SetLocal* curr) {
+ // Undo an if return value into a local, if one arm is a br, as we
+ // prefer a br_if:
+ // (set_local $x
+ // (if (result i32)
+ // (..condition..)
+ // (br $somewhere)
+ // (..result)
+ // )
+ // )
+ // =>
+ // (br_if $somewhere
+ // (..condition..)
+ // )
+ // (set_local $x
+ // (..result)
+ // )
+ // TODO: handle a condition in the br? need to watch for side effects
+ auto* iff = curr->value->dynCast<If>();
+ if (!iff) return;
+ if (!isConcreteType(iff->type)) return;
+ auto tryToOptimize = [&](Expression* one, Expression* two, bool flipCondition) {
+ if (one->type == unreachable && two->type != unreachable) {
+ if (auto* br = one->dynCast<Break>()) {
+ if (ExpressionAnalyzer::isSimple(br)) {
+ // Wonderful, do it!
+ Builder builder(*getModule());
+ br->condition = iff->condition;
+ if (flipCondition) {
+ br->condition = builder.makeUnary(EqZInt32, br->condition);
+ }
+ br->finalize();
+ curr->value = two;
+ replaceCurrent(
+ builder.makeSequence(
+ br,
+ curr
+ )
+ );
+ return true;
+ }
+ }
+ }
+ return false;
+ };
+ if (!tryToOptimize(iff->ifTrue, iff->ifFalse, false)) {
+ tryToOptimize(iff->ifFalse, iff->ifTrue, true);
+ }
+ }
+
// (br_if)+ => br_table
// we look for the specific pattern of
// (br_if ..target1..
diff --git a/src/passes/SimplifyLocals.cpp b/src/passes/SimplifyLocals.cpp
index 4db85eb3e..6c1ea3fcb 100644
--- a/src/passes/SimplifyLocals.cpp
+++ b/src/passes/SimplifyLocals.cpp
@@ -456,16 +456,46 @@ struct SimplifyLocals : public WalkerPass<LinearExecutionWalker<SimplifyLocals<a
// if this if already has a result, or is unreachable code, we have
// nothing to do
if (iff->type != none) return;
- // We now have the sinkables from both sides of the if.
+ // We now have the sinkables from both sides of the if, and can look
+ // for something to sink. That is either a shared index on both sides,
+ // *or* if one side is unreachable, we can sink anything from the other,
+ // (if
+ // (..)
+ // (br $x)
+ // (set_local $y (..))
+ // )
+ // =>
+ // (set_local $y
+ // (if (result i32)
+ // (..)
+ // (br $x)
+ // (..)
+ // )
+ // )
Sinkables& ifFalse = sinkables;
- Index sharedIndex = -1;
+ Index goodIndex = -1;
bool found = false;
- for (auto& sinkable : ifTrue) {
- Index index = sinkable.first;
- if (ifFalse.count(index) > 0) {
- sharedIndex = index;
+ if (iff->ifTrue->type == unreachable) {
+ assert(iff->ifFalse->type != unreachable); // since the if type is none
+ if (!ifFalse.empty()) {
+ goodIndex = ifFalse.begin()->first;
found = true;
- break;
+ }
+ } else if (iff->ifFalse->type == unreachable) {
+ assert(iff->ifTrue->type != unreachable); // since the if type is none
+ if (!ifTrue.empty()) {
+ goodIndex = ifTrue.begin()->first;
+ found = true;
+ }
+ } else {
+ // Look for a shared index.
+ for (auto& sinkable : ifTrue) {
+ Index index = sinkable.first;
+ if (ifFalse.count(index) > 0) {
+ goodIndex = index;
+ found = true;
+ break;
+ }
}
}
if (!found) return;
@@ -473,27 +503,38 @@ struct SimplifyLocals : public WalkerPass<LinearExecutionWalker<SimplifyLocals<a
// ensure we have a place to write the return values for, if not, we
// need another cycle
auto* ifTrueBlock = iff->ifTrue->dynCast<Block>();
+ if (iff->ifTrue->type != unreachable) {
+ if (!ifTrueBlock || ifTrueBlock->list.size() == 0 || !ifTrueBlock->list.back()->is<Nop>()) {
+ ifsToEnlarge.push_back(iff);
+ return;
+ }
+ }
auto* ifFalseBlock = iff->ifFalse->dynCast<Block>();
- if (!ifTrueBlock || ifTrueBlock->list.size() == 0 || !ifTrueBlock->list.back()->is<Nop>() ||
- !ifFalseBlock || ifFalseBlock->list.size() == 0 || !ifFalseBlock->list.back()->is<Nop>()) {
- ifsToEnlarge.push_back(iff);
- return;
+ if (iff->ifFalse->type != unreachable) {
+ if (!ifFalseBlock || ifFalseBlock->list.size() == 0 || !ifFalseBlock->list.back()->is<Nop>()) {
+ ifsToEnlarge.push_back(iff);
+ return;
+ }
}
// all set, go
- auto *ifTrueItem = ifTrue.at(sharedIndex).item;
- ifTrueBlock->list[ifTrueBlock->list.size() - 1] = (*ifTrueItem)->template cast<SetLocal>()->value;
- ExpressionManipulator::nop(*ifTrueItem);
- ifTrueBlock->finalize();
- assert(ifTrueBlock->type != none);
- auto *ifFalseItem = ifFalse.at(sharedIndex).item;
- ifFalseBlock->list[ifFalseBlock->list.size() - 1] = (*ifFalseItem)->template cast<SetLocal>()->value;
- ExpressionManipulator::nop(*ifFalseItem);
- ifFalseBlock->finalize();
- assert(ifTrueBlock->type != none);
+ if (iff->ifTrue->type != unreachable) {
+ auto *ifTrueItem = ifTrue.at(goodIndex).item;
+ ifTrueBlock->list[ifTrueBlock->list.size() - 1] = (*ifTrueItem)->template cast<SetLocal>()->value;
+ ExpressionManipulator::nop(*ifTrueItem);
+ ifTrueBlock->finalize();
+ assert(ifTrueBlock->type != none);
+ }
+ if (iff->ifFalse->type != unreachable) {
+ auto *ifFalseItem = ifFalse.at(goodIndex).item;
+ ifFalseBlock->list[ifFalseBlock->list.size() - 1] = (*ifFalseItem)->template cast<SetLocal>()->value;
+ ExpressionManipulator::nop(*ifFalseItem);
+ ifFalseBlock->finalize();
+ assert(ifFalseBlock->type != none);
+ }
iff->finalize(); // update type
assert(iff->type != none);
// finally, create a set_local on the iff itself
- auto* newSetLocal = Builder(*this->getModule()).makeSetLocal(sharedIndex, iff);
+ auto* newSetLocal = Builder(*this->getModule()).makeSetLocal(goodIndex, iff);
*currp = newSetLocal;
anotherCycle = true;
}