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-rw-r--r--src/cfg/cfg-traversal.h49
-rw-r--r--src/passes/CoalesceLocals.cpp11
-rw-r--r--test/passes/coalesce-locals-learning.txt24
-rw-r--r--test/passes/coalesce-locals.txt61
-rw-r--r--test/passes/coalesce-locals.wast29
5 files changed, 126 insertions, 48 deletions
diff --git a/src/cfg/cfg-traversal.h b/src/cfg/cfg-traversal.h
index 5bc593691..99bc25ea8 100644
--- a/src/cfg/cfg-traversal.h
+++ b/src/cfg/cfg-traversal.h
@@ -56,17 +56,29 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
std::vector<std::unique_ptr<BasicBlock>> basicBlocks; // all the blocks
// traversal state
- BasicBlock* currBasicBlock; // the current block in play during traversal
+ BasicBlock* currBasicBlock; // the current block in play during traversal. can be nullptr if unreachable,
+ // but note that we don't do a deep unreachability analysis - just enough
+ // to avoid constructing obviously-unreachable blocks (we do a full reachability
+ // analysis on the CFG once it is constructed).
std::map<Expression*, std::vector<BasicBlock*>> branches; // a block or loop => its branches
std::vector<BasicBlock*> ifStack;
std::vector<BasicBlock*> loopStack;
- static void doStartBasicBlock(SubType* self, Expression** currp) {
- self->currBasicBlock = self->makeBasicBlock();
- self->basicBlocks.push_back(std::unique_ptr<BasicBlock>(self->currBasicBlock));
+ void startBasicBlock() {
+ currBasicBlock = makeBasicBlock();
+ basicBlocks.push_back(std::unique_ptr<BasicBlock>(currBasicBlock));
+ }
+
+ void startUnreachableBlock() {
+ currBasicBlock = nullptr;
+ }
+
+ static void doStartUnreachableBlock(SubType* self, Expression** currp) {
+ self->startUnreachableBlock();
}
void link(BasicBlock* from, BasicBlock* to) {
+ if (!from || !to) return; // if one of them is not reachable, ignore
from->out.push_back(to);
to->in.push_back(from);
}
@@ -80,7 +92,7 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
if (origins.size() == 0) return;
// we have branches to here, so we need a new block
auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // fallthrough
// branches to the new one
for (auto* origin : origins) {
@@ -91,20 +103,20 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
static void doStartIfTrue(SubType* self, Expression** currp) {
auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // ifTrue
self->ifStack.push_back(last); // the block before the ifTrue
}
static void doStartIfFalse(SubType* self, Expression** currp) {
self->ifStack.push_back(self->currBasicBlock); // the ifTrue fallthrough
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(self->ifStack[self->ifStack.size() - 2], self->currBasicBlock); // before if -> ifFalse
}
static void doEndIf(SubType* self, Expression** currp) {
auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // last one is ifFalse's fallthrough if there was one, otherwise it's the ifTrue fallthrough
if ((*currp)->cast<If>()->ifFalse) {
// we just linked ifFalse, need to link ifTrue to the end
@@ -119,14 +131,14 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
static void doStartLoop(SubType* self, Expression** currp) {
auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(last, self->currBasicBlock);
self->loopStack.push_back(self->currBasicBlock);
}
static void doEndLoop(SubType* self, Expression** currp) {
auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // fallthrough
auto* curr = (*currp)->cast<Loop>();
// branches to the top of the loop
@@ -144,10 +156,12 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
static void doEndBreak(SubType* self, Expression** currp) {
auto* curr = (*currp)->cast<Break>();
self->branches[self->findBreakTarget(curr->name)].push_back(self->currBasicBlock); // branch to the target
- auto* last = self->currBasicBlock;
- doStartBasicBlock(self, currp);
if (curr->condition) {
+ auto* last = self->currBasicBlock;
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // we might fall through
+ } else {
+ self->startUnreachableBlock();
}
}
@@ -163,7 +177,7 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
if (!seen.count(curr->default_)) {
self->branches[self->findBreakTarget(curr->default_)].push_back(self->currBasicBlock); // branch to the target
}
- doStartBasicBlock(self, currp);
+ self->startUnreachableBlock();
}
static void scan(SubType* self, Expression** currp) {
@@ -175,9 +189,7 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
break;
}
case Expression::Id::IfId: {
- self->pushTask(SubType::doPostVisitControlFlow, currp);
self->pushTask(SubType::doEndIf, currp);
- self->pushTask(SubType::doVisitIf, currp);
auto* ifFalse = curr->cast<If>()->ifFalse;
if (ifFalse) {
self->pushTask(SubType::scan, &curr->cast<If>()->ifFalse);
@@ -186,7 +198,6 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
self->pushTask(SubType::scan, &curr->cast<If>()->ifTrue);
self->pushTask(SubType::doStartIfTrue, currp);
self->pushTask(SubType::scan, &curr->cast<If>()->condition);
- self->pushTask(SubType::doPreVisitControlFlow, currp);
return; // don't do anything else
}
case Expression::Id::LoopId: {
@@ -202,11 +213,11 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
break;
}
case Expression::Id::ReturnId: {
- self->pushTask(SubType::doStartBasicBlock, currp);
+ self->pushTask(SubType::doStartUnreachableBlock, currp);
break;
}
case Expression::Id::UnreachableId: {
- self->pushTask(SubType::doStartBasicBlock, currp);
+ self->pushTask(SubType::doStartUnreachableBlock, currp);
break;
}
default: {}
@@ -226,7 +237,7 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
void doWalkFunction(Function* func) {
basicBlocks.clear();
- doStartBasicBlock(static_cast<SubType*>(this), nullptr);
+ startBasicBlock();
entry = currBasicBlock;
ControlFlowWalker<SubType, VisitorType>::doWalkFunction(func);
diff --git a/src/passes/CoalesceLocals.cpp b/src/passes/CoalesceLocals.cpp
index ba2c6dd81..2ff1dde37 100644
--- a/src/passes/CoalesceLocals.cpp
+++ b/src/passes/CoalesceLocals.cpp
@@ -169,13 +169,22 @@ struct CoalesceLocals : public WalkerPass<CFGWalker<CoalesceLocals, Visitor<Coal
static void doVisitGetLocal(CoalesceLocals* self, Expression** currp) {
auto* curr = (*currp)->cast<GetLocal>();
+ // if in unreachable code, ignore
+ if (!self->currBasicBlock) {
+ ExpressionManipulator::convert<GetLocal, Unreachable>(curr);
+ return;
+ }
self->currBasicBlock->contents.actions.emplace_back(Action::Get, curr->index, currp);
}
static void doVisitSetLocal(CoalesceLocals* self, Expression** currp) {
auto* curr = (*currp)->cast<SetLocal>();
+ // if in unreachable code, ignore
+ if (!self->currBasicBlock) {
+ ExpressionManipulator::nop(curr);
+ return;
+ }
self->currBasicBlock->contents.actions.emplace_back(Action::Set, curr->index, currp);
-
// if this is a copy, note it
auto* get = curr->value->dynCast<GetLocal>();
if (get) self->addCopy(curr->index, get->index);
diff --git a/test/passes/coalesce-locals-learning.txt b/test/passes/coalesce-locals-learning.txt
index 49afc98ec..ef8d31174 100644
--- a/test/passes/coalesce-locals-learning.txt
+++ b/test/passes/coalesce-locals-learning.txt
@@ -108,15 +108,11 @@
)
(block $block
(br $block)
+ (nop)
(drop
- (i32.const 0)
- )
- (drop
- (get_local $0)
- )
- (drop
- (i32.const -1)
+ (unreachable)
)
+ (nop)
)
(drop
(get_local $0)
@@ -395,10 +391,10 @@
(block $block
(br $block)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -407,10 +403,10 @@
(block $block
(unreachable)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -419,10 +415,10 @@
(block $block
(return)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -466,7 +462,7 @@
(i32.const 100)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
(drop
diff --git a/test/passes/coalesce-locals.txt b/test/passes/coalesce-locals.txt
index 1f89b9fa7..08573a790 100644
--- a/test/passes/coalesce-locals.txt
+++ b/test/passes/coalesce-locals.txt
@@ -108,15 +108,11 @@
)
(block $block
(br $block)
+ (nop)
(drop
- (i32.const 0)
- )
- (drop
- (get_local $0)
- )
- (drop
- (i32.const -1)
+ (unreachable)
)
+ (nop)
)
(drop
(get_local $0)
@@ -393,10 +389,10 @@
(block $block
(br $block)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -405,10 +401,10 @@
(block $block
(unreachable)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -417,10 +413,10 @@
(block $block
(return)
(drop
- (get_local $0)
+ (unreachable)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
)
@@ -464,7 +460,7 @@
(i32.const 100)
)
(drop
- (get_local $0)
+ (unreachable)
)
)
(drop
@@ -898,4 +894,41 @@
(get_local $0)
)
)
+ (func $in-unreachable (type $2)
+ (local $0 i32)
+ (block $x
+ (return)
+ (nop)
+ (drop
+ (unreachable)
+ )
+ (nop)
+ )
+ (block $y
+ (unreachable)
+ (nop)
+ (drop
+ (unreachable)
+ )
+ (nop)
+ )
+ (block $z
+ (br $z)
+ (nop)
+ (drop
+ (unreachable)
+ )
+ (nop)
+ )
+ (block $z14
+ (br_table $z14 $z14
+ (i32.const 100)
+ )
+ (nop)
+ (drop
+ (unreachable)
+ )
+ (nop)
+ )
+ )
)
diff --git a/test/passes/coalesce-locals.wast b/test/passes/coalesce-locals.wast
index da71b7665..26d90ff49 100644
--- a/test/passes/coalesce-locals.wast
+++ b/test/passes/coalesce-locals.wast
@@ -925,4 +925,33 @@
(get_local $z)
)
)
+ (func $in-unreachable
+ (local $a i32)
+ (block $x
+ (return)
+ (set_local $a (i32.const 1))
+ (drop (get_local $a))
+ (set_local $a (get_local $a))
+ )
+ (block $y
+ (unreachable)
+ (set_local $a (i32.const 1))
+ (drop (get_local $a))
+ (set_local $a (get_local $a))
+ )
+ (block $z
+ (br $z)
+ (set_local $a (i32.const 1))
+ (drop (get_local $a))
+ (set_local $a (get_local $a))
+ )
+ (block $z
+ (br_table $z $z
+ (i32.const 100)
+ )
+ (set_local $a (i32.const 1))
+ (drop (get_local $a))
+ (set_local $a (get_local $a))
+ )
+ )
)
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-05 19:07:44 +0000