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path: root/src/passes/RemoveUnusedBrs.cpp
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Diffstat (limited to 'src/passes/RemoveUnusedBrs.cpp')
-rw-r--r--src/passes/RemoveUnusedBrs.cpp84
1 files changed, 56 insertions, 28 deletions
diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index 4b5c9613e..20811efef 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -36,13 +36,16 @@ static bool canTurnIfIntoBrIf(Expression* ifCondition,
Expression* brValue,
PassOptions& options) {
// if the if isn't even reached, this is all dead code anyhow
- if (ifCondition->type == unreachable)
+ if (ifCondition->type == unreachable) {
return false;
- if (!brValue)
+ }
+ if (!brValue) {
return true;
+ }
EffectAnalyzer value(options, brValue);
- if (value.hasSideEffects())
+ if (value.hasSideEffects()) {
return false;
+ }
return !EffectAnalyzer(options, ifCondition).invalidates(value);
}
@@ -219,8 +222,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
}
// when there isn't a value, we can do some trivial optimizations without
// worrying about the value being executed before the condition
- if (curr->value)
+ if (curr->value) {
return;
+ }
if (curr->targets.size() == 0) {
// a switch with just a default always goes there
Builder builder(*getModule());
@@ -344,19 +348,23 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
// helpful, as it shortens the logical loop. it is also good to generate
// an if-else instead of an if, as it might allow an eqz to be removed
// by flipping arms)
- if (!loop->name.is())
+ if (!loop->name.is()) {
return false;
+ }
auto* block = loop->body->dynCast<Block>();
- if (!block)
+ if (!block) {
return false;
+ }
// does the last element break to the top of the loop?
auto& list = block->list;
- if (list.size() <= 1)
+ if (list.size() <= 1) {
return false;
+ }
auto* last = list.back()->dynCast<Break>();
if (!last || !ExpressionAnalyzer::isSimple(last) ||
- last->name != loop->name)
+ last->name != loop->name) {
return false;
+ }
// last is a simple break to the top of the loop. if we can conditionalize
// it, it won't block things from flowing out and not needing breaks to do
// so.
@@ -391,8 +399,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
auto blockifyMerge = [&](Expression* any,
Expression* append) -> Block* {
Block* block = nullptr;
- if (any)
+ if (any) {
block = any->dynCast<Block>();
+ }
// if the first isn't a block, or it's a block with a name (so we
// might branch to the end, and so can't append to it, we might skip
// that code!) then make a new block
@@ -468,8 +477,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
if (EffectAnalyzer(getPassOptions(), curr).branches) {
return false;
}
- if (i == 0)
+ if (i == 0) {
return false;
+ }
i--;
}
}
@@ -560,8 +570,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
// optimized
for (Index i = 0; i < flows.size(); i++) {
auto* flow = (*flows[i])->dynCast<Return>();
- if (!flow)
+ if (!flow) {
continue;
+ }
if (!flow->value) {
// return => nop
ExpressionManipulator::nop(flow);
@@ -689,10 +700,11 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
auto& list = curr->list;
for (Index i = 0; i < list.size(); i++) {
auto* iff = list[i]->dynCast<If>();
- if (!iff || !iff->ifFalse)
+ if (!iff || !iff->ifFalse) {
// if it lacked an if-false, it would already be a br_if, as that's
// the easy case
continue;
+ }
auto* ifTrueBreak = iff->ifTrue->dynCast<Break>();
if (ifTrueBreak && !ifTrueBreak->condition &&
canTurnIfIntoBrIf(
@@ -724,12 +736,14 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
auto* br1 = list[i]->dynCast<Break>();
// avoid unreachable brs, as they are dead code anyhow, and after
// merging them the outer scope could need type changes
- if (!br1 || !br1->condition || br1->type == unreachable)
+ if (!br1 || !br1->condition || br1->type == unreachable) {
continue;
+ }
assert(!br1->value);
auto* br2 = list[i + 1]->dynCast<Break>();
- if (!br2 || br1->name != br2->name)
+ if (!br2 || br1->name != br2->name) {
continue;
+ }
assert(!br2->value); // same target as previous, which has no value
// a br_if and then a br[_if] with the same target right after it
if (br2->condition) {
@@ -862,8 +876,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
const auto MAX_COST = 7;
auto total =
CostAnalyzer(iff->ifTrue).cost + CostAnalyzer(iff->ifFalse).cost;
- if (total >= MAX_COST)
+ if (total >= MAX_COST) {
return nullptr;
+ }
}
// Check if side effects allow this.
EffectAnalyzer condition(passOptions, iff->condition);
@@ -889,10 +904,12 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
}
void optimizeSetIf(Expression** currp) {
- if (optimizeSetIfWithBrArm(currp))
+ if (optimizeSetIfWithBrArm(currp)) {
return;
- if (optimizeSetIfWithCopyArm(currp))
+ }
+ if (optimizeSetIfWithCopyArm(currp)) {
return;
+ }
}
// If one arm is a br, we prefer a br_if and the set later:
@@ -1003,8 +1020,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
get = nullptr;
}
}
- if (!get)
+ if (!get) {
return false;
+ }
// We can do it!
bool tee = set->isTee();
assert(set->index == get->index);
@@ -1045,8 +1063,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
// TODO: consider also looking at <= etc. and not just eq
void tablify(Block* block) {
auto& list = block->list;
- if (list.size() <= 1)
+ if (list.size() <= 1) {
return;
+ }
// Heuristics. These are slightly inspired by the constants from the
// asm.js backend.
@@ -1065,25 +1084,32 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
// or nullptr otherwise
auto getProperBrIf = [](Expression* curr) -> Break* {
auto* br = curr->dynCast<Break>();
- if (!br)
+ if (!br) {
return nullptr;
- if (!br->condition || br->value)
+ }
+ if (!br->condition || br->value) {
return nullptr;
- if (br->type != none)
+ }
+ if (br->type != none) {
// no value, so can be unreachable or none. ignore unreachable ones,
// dce will clean it up
return nullptr;
+ }
auto* binary = br->condition->dynCast<Binary>();
- if (!binary)
+ if (!binary) {
return nullptr;
- if (binary->op != EqInt32)
+ }
+ if (binary->op != EqInt32) {
return nullptr;
+ }
auto* c = binary->right->dynCast<Const>();
- if (!c)
+ if (!c) {
return nullptr;
+ }
uint32_t value = c->value.geti32();
- if (value >= uint32_t(std::numeric_limits<int32_t>::max()))
+ if (value >= uint32_t(std::numeric_limits<int32_t>::max())) {
return nullptr;
+ }
return br;
};
@@ -1092,8 +1118,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
auto getProperBrIfConditionValue =
[&getProperBrIf](Expression* curr) -> Expression* {
auto* br = getProperBrIf(curr);
- if (!br)
+ if (!br) {
return nullptr;
+ }
return br->condition->cast<Binary>()->left;
};
@@ -1160,8 +1187,9 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
Index i = 0;
while (1) {
defaultName = "tablify|" + std::to_string(i++);
- if (usedNames.count(defaultName) == 0)
+ if (usedNames.count(defaultName) == 0) {
break;
+ }
}
std::vector<Name> table;
for (Index i = start; i < end; i++) {
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-07 06:34:58 +0000