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-rw-r--r--src/cfg/cfg-traversal.h25
-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, 113 insertions, 37 deletions
diff --git a/src/cfg/cfg-traversal.h b/src/cfg/cfg-traversal.h
index 668bdfef2..004f23752 100644
--- a/src/cfg/cfg-traversal.h
+++ b/src/cfg/cfg-traversal.h
@@ -56,7 +56,9 @@ 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 be useful, given that DCE has run before.
std::map<Expression*, std::vector<BasicBlock*>> branches; // a block or loop => its branches
std::vector<BasicBlock*> ifStack;
std::vector<BasicBlock*> loopStack;
@@ -66,11 +68,16 @@ struct CFGWalker : public ControlFlowWalker<SubType, VisitorType> {
basicBlocks.push_back(std::unique_ptr<BasicBlock>(currBasicBlock));
}
- static void doStartBasicBlock(SubType* self, Expression** currp) {
- self->startBasicBlock();
+ 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);
}
@@ -148,10 +155,12 @@ 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;
- self->startBasicBlock();
if (curr->condition) {
+ auto* last = self->currBasicBlock;
+ self->startBasicBlock();
self->link(last, self->currBasicBlock); // we might fall through
+ } else {
+ self->startUnreachableBlock();
}
}
@@ -167,7 +176,7 @@ 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
}
- self->startBasicBlock();
+ self->startUnreachableBlock();
}
static void scan(SubType* self, Expression** currp) {
@@ -203,11 +212,11 @@ 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: {}
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 2025-08-08 04:59:37 +0000