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-rw-r--r--src/passes/MergeBlocks.cpp133
-rw-r--r--test/passes/merge-blocks.txt41
-rw-r--r--test/passes/merge-blocks.wast15
3 files changed, 117 insertions, 72 deletions
diff --git a/src/passes/MergeBlocks.cpp b/src/passes/MergeBlocks.cpp
index edfa1336b..95d680ec7 100644
--- a/src/passes/MergeBlocks.cpp
+++ b/src/passes/MergeBlocks.cpp
@@ -110,9 +110,13 @@ struct ProblemFinder : public ControlFlowWalker<ProblemFinder, Visitor<ProblemFi
}
};
+// Drops values from breaks to an origin.
+// While doing so it can create new blocks, so optimize blocks as well.
struct BreakValueDropper : public ControlFlowWalker<BreakValueDropper, Visitor<BreakValueDropper>> {
Name origin;
+ void visitBlock(Block* curr);
+
void visitBreak(Break* curr) {
if (curr->value && curr->name == origin) {
Builder builder(*getModule());
@@ -131,72 +135,81 @@ struct BreakValueDropper : public ControlFlowWalker<BreakValueDropper, Visitor<B
}
};
-struct MergeBlocks : public WalkerPass<PostWalker<MergeBlocks, Visitor<MergeBlocks>>> {
- bool isFunctionParallel() override { return true; }
-
- Pass* create() override { return new MergeBlocks; }
-
- void visitBlock(Block *curr) {
- bool more = true;
- bool changed = false;
- while (more) {
- more = false;
- for (size_t i = 0; i < curr->list.size(); i++) {
- Block* child = curr->list[i]->dynCast<Block>();
- if (!child) {
- // if we have a child that is (drop (block ..)) then we can move the drop into the block, and remove br values. this allows more merging,
- auto* drop = curr->list[i]->dynCast<Drop>();
- if (drop) {
- child = drop->value->dynCast<Block>();
- if (child) {
- if (child->name.is()) {
- Expression* expression = child;
- // check if it's ok to remove the value from all breaks to us
- ProblemFinder finder;
- finder.origin = child->name;
- finder.walk(expression);
- if (finder.found()) {
- child = nullptr;
- } else {
- // fix up breaks
- BreakValueDropper fixer;
- fixer.origin = child->name;
- fixer.setModule(getModule());
- fixer.walk(expression);
- }
- }
- if (child) {
- // we can do it!
- // reuse the drop
- drop->value = child->list.back();
- child->list.back() = drop;
- child->finalize();
- curr->list[i] = child;
- more = true;
- changed = true;
+// core block optimizer routine
+static void optimizeBlock(Block* curr, Module* module) {
+ bool more = true;
+ bool changed = false;
+ while (more) {
+ more = false;
+ for (size_t i = 0; i < curr->list.size(); i++) {
+ Block* child = curr->list[i]->dynCast<Block>();
+ if (!child) {
+ // if we have a child that is (drop (block ..)) then we can move the drop into the block, and remove br values. this allows more merging,
+ auto* drop = curr->list[i]->dynCast<Drop>();
+ if (drop) {
+ child = drop->value->dynCast<Block>();
+ if (child) {
+ if (child->name.is()) {
+ Expression* expression = child;
+ // check if it's ok to remove the value from all breaks to us
+ ProblemFinder finder;
+ finder.origin = child->name;
+ finder.walk(expression);
+ if (finder.found()) {
+ child = nullptr;
+ } else {
+ // fix up breaks
+ BreakValueDropper fixer;
+ fixer.origin = child->name;
+ fixer.setModule(module);
+ fixer.walk(expression);
}
}
+ if (child) {
+ // we can do it!
+ // reuse the drop
+ drop->value = child->list.back();
+ child->list.back() = drop;
+ child->finalize();
+ curr->list[i] = child;
+ more = true;
+ changed = true;
+ }
}
}
- if (!child) continue;
- if (child->name.is()) continue; // named blocks can have breaks to them (and certainly do, if we ran RemoveUnusedNames and RemoveUnusedBrs)
- ExpressionList merged(getModule()->allocator);
- for (size_t j = 0; j < i; j++) {
- merged.push_back(curr->list[j]);
- }
- for (auto item : child->list) {
- merged.push_back(item);
- }
- for (size_t j = i + 1; j < curr->list.size(); j++) {
- merged.push_back(curr->list[j]);
- }
- curr->list = merged;
- more = true;
- changed = true;
- break;
}
+ if (!child) continue;
+ if (child->name.is()) continue; // named blocks can have breaks to them (and certainly do, if we ran RemoveUnusedNames and RemoveUnusedBrs)
+ ExpressionList merged(module->allocator);
+ for (size_t j = 0; j < i; j++) {
+ merged.push_back(curr->list[j]);
+ }
+ for (auto item : child->list) {
+ merged.push_back(item);
+ }
+ for (size_t j = i + 1; j < curr->list.size(); j++) {
+ merged.push_back(curr->list[j]);
+ }
+ curr->list = merged;
+ more = true;
+ changed = true;
+ break;
}
- if (changed) curr->finalize();
+ }
+ if (changed) curr->finalize();
+}
+
+void BreakValueDropper::visitBlock(Block* curr) {
+ optimizeBlock(curr, getModule());
+}
+
+struct MergeBlocks : public WalkerPass<PostWalker<MergeBlocks, Visitor<MergeBlocks>>> {
+ bool isFunctionParallel() override { return true; }
+
+ Pass* create() override { return new MergeBlocks; }
+
+ void visitBlock(Block *curr) {
+ optimizeBlock(curr, getModule());
}
Block* optimize(Expression* curr, Expression*& child, Block* outer = nullptr, Expression** dependency1 = nullptr, Expression** dependency2 = nullptr) {
diff --git a/test/passes/merge-blocks.txt b/test/passes/merge-blocks.txt
index 1116e0d28..ae34bea05 100644
--- a/test/passes/merge-blocks.txt
+++ b/test/passes/merge-blocks.txt
@@ -14,12 +14,10 @@
(func $drop-block-br (type $0)
(block $block
(block $x
- (block
- (drop
- (i32.const 1)
- )
- (br $x)
+ (drop
+ (i32.const 1)
)
+ (br $x)
(drop
(i32.const 0)
)
@@ -29,13 +27,11 @@
(func $drop-block-br-if (type $0)
(block $block
(block $x
- (block
- (drop
- (i32.const 1)
- )
- (br_if $x
- (i32.const 2)
- )
+ (drop
+ (i32.const 1)
+ )
+ (br_if $x
+ (i32.const 2)
)
(drop
(i32.const 0)
@@ -58,4 +54,25 @@
)
)
)
+ (func $drop-block-nested-br-if (type $0)
+ (block $block
+ (block $x
+ (if
+ (i32.const 100)
+ (block $block0
+ (drop
+ (i32.const 1)
+ )
+ (br_if $x
+ (i32.const 2)
+ )
+ (nop)
+ )
+ )
+ (drop
+ (i32.const 0)
+ )
+ )
+ )
+ )
)
diff --git a/test/passes/merge-blocks.wast b/test/passes/merge-blocks.wast
index 161f9d90f..e0da890a1 100644
--- a/test/passes/merge-blocks.wast
+++ b/test/passes/merge-blocks.wast
@@ -38,5 +38,20 @@
)
)
)
+ (func $drop-block-nested-br-if
+ (block
+ (drop
+ (block $x i32
+ (if (i32.const 100)
+ (block
+ (drop (br_if $x (i32.const 1) (i32.const 2)))
+ (nop)
+ )
+ )
+ (i32.const 0)
+ )
+ )
+ )
+ )
)
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-08 13:07:10 +0000