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-rw-r--r--src/ir/local-graph.h2
-rw-r--r--src/passes/SSAify.cpp86
-rw-r--r--test/passes/ssa.txt91
-rw-r--r--test/passes/ssa.wast44
4 files changed, 154 insertions, 69 deletions
diff --git a/src/ir/local-graph.h b/src/ir/local-graph.h
index 6a8f1b2af..84be2a4c2 100644
--- a/src/ir/local-graph.h
+++ b/src/ir/local-graph.h
@@ -42,7 +42,7 @@ struct LocalGraph {
// externally useful information
GetSetses getSetses; // the sets affecting each get. a nullptr set means the initial
- // value (0 for a var, the received value for a param)
+ // value (0 for a var, the received value for a param)
Locations locations; // where each get and set is (for easy replacing)
// optional computation: compute the influence graphs between sets and gets
diff --git a/src/passes/SSAify.cpp b/src/passes/SSAify.cpp
index 9c680b942..a6127e4d6 100644
--- a/src/passes/SSAify.cpp
+++ b/src/passes/SSAify.cpp
@@ -99,68 +99,38 @@ struct SSAify : public Pass {
continue;
}
// more than 1 set, need a phi: a new local written to at each of the sets
- // if there is already a local with that property, reuse it
- auto gatherIndexes = [](SetLocal* set) {
- std::set<Index> ret;
- while (set) {
- ret.insert(set->index);
- set = set->value->dynCast<SetLocal>();
- }
- return ret;
- };
- auto indexes = gatherIndexes(*sets.begin());
+ auto new_ = addLocal(get->type);
+ auto old = get->index;
+ get->index = new_;
+ Builder builder(*module);
+ // write to the local in each of our sets
for (auto* set : sets) {
- if (set == *sets.begin()) continue;
- auto currIndexes = gatherIndexes(set);
- std::vector<Index> intersection;
- std::set_intersection(indexes.begin(), indexes.end(),
- currIndexes.begin(), currIndexes.end(),
- std::back_inserter(intersection));
- indexes.clear();
- if (intersection.empty()) break;
- // TODO: or keep sorted vectors?
- for (Index i : intersection) {
- indexes.insert(i);
- }
- }
- if (!indexes.empty()) {
- // we found an index, use it
- get->index = *indexes.begin();
- } else {
- // we need to create a local for this phi'ing
- auto new_ = addLocal(get->type);
- auto old = get->index;
- get->index = new_;
- Builder builder(*module);
- // write to the local in each of our sets
- for (auto* set : sets) {
- if (set) {
- // a set exists, just add a tee of its value
- auto* value = set->value;
- auto* tee = builder.makeTeeLocal(
+ if (set) {
+ // a set exists, just add a tee of its value
+ auto* value = set->value;
+ auto* tee = builder.makeTeeLocal(
+ new_,
+ value
+ );
+ set->value = tee;
+ // the value may have been something we tracked the location
+ // of. if so, update that, since we moved it into the tee
+ if (graph.locations.count(value) > 0) {
+ assert(graph.locations[value] == &set->value);
+ graph.locations[value] = &tee->value;
+ }
+ } else {
+ // this is a param or the zero init value.
+ if (func->isParam(old)) {
+ // we add a set with the proper
+ // param value at the beginning of the function
+ auto* set = builder.makeSetLocal(
new_,
- value
+ builder.makeGetLocal(old, func->getLocalType(old))
);
- set->value = tee;
- // the value may have been something we tracked the location
- // of. if so, update that, since we moved it into the tee
- if (graph.locations.count(value) > 0) {
- assert(graph.locations[value] == &set->value);
- graph.locations[value] = &tee->value;
- }
+ functionPrepends.push_back(set);
} else {
- // this is a param or the zero init value.
- if (func->isParam(old)) {
- // we add a set with the proper
- // param value at the beginning of the function
- auto* set = builder.makeSetLocal(
- new_,
- builder.makeGetLocal(old, func->getLocalType(old))
- );
- functionPrepends.push_back(set);
- } else {
- // this is a zero init, so we don't need to do anything actually
- }
+ // this is a zero init, so we don't need to do anything actually
}
}
}
diff --git a/test/passes/ssa.txt b/test/passes/ssa.txt
index 657ccc128..e6883c0f8 100644
--- a/test/passes/ssa.txt
+++ b/test/passes/ssa.txt
@@ -442,9 +442,12 @@
(local $4 i32)
(local $5 i32)
(local $6 i32)
+ (local $7 i32)
(set_local $3
- (tee_local $6
- (get_local $param)
+ (tee_local $7
+ (tee_local $6
+ (get_local $param)
+ )
)
)
(loop $more
@@ -460,15 +463,17 @@
)
)
(set_local $5
- (tee_local $6
- (get_local $4)
+ (tee_local $7
+ (tee_local $6
+ (get_local $4)
+ )
)
)
(br $more)
)
)
(drop
- (get_local $6)
+ (get_local $7)
)
)
(func $real-loop-outblock (; 9 ;) (type $0) (param $param i32)
@@ -478,9 +483,12 @@
(local $4 i32)
(local $5 i32)
(local $6 i32)
+ (local $7 i32)
(set_local $3
- (tee_local $6
- (get_local $param)
+ (tee_local $7
+ (tee_local $6
+ (get_local $param)
+ )
)
)
(block $stop
@@ -496,15 +504,17 @@
)
)
(set_local $5
- (tee_local $6
- (get_local $4)
+ (tee_local $7
+ (tee_local $6
+ (get_local $4)
+ )
)
)
(br $more)
)
)
(drop
- (get_local $6)
+ (get_local $7)
)
)
(func $loop-loop-param (; 10 ;) (type $0) (param $param i32)
@@ -726,4 +736,65 @@
(br $label$1)
)
)
+ (func $ssa-merge-tricky (; 15 ;) (type $2) (result i32)
+ (local $var$0 i32)
+ (local $var$1 i32)
+ (local $2 i32)
+ (local $3 i32)
+ (local $4 i32)
+ (local $5 i32)
+ (local $6 i32)
+ (local $7 i32)
+ (local $8 i32)
+ (set_local $2
+ (tee_local $8
+ (tee_local $3
+ (tee_local $7
+ (i32.const 0)
+ )
+ )
+ )
+ )
+ (loop $label$1
+ (if
+ (i32.eqz
+ (get_global $global$0)
+ )
+ (return
+ (i32.const 12345)
+ )
+ )
+ (set_global $global$0
+ (i32.const 0)
+ )
+ (if
+ (i32.eqz
+ (get_local $7)
+ )
+ (br_if $label$1
+ (i32.eqz
+ (tee_local $4
+ (tee_local $7
+ (i32.const 1)
+ )
+ )
+ )
+ )
+ )
+ (br_if $label$1
+ (i32.eqz
+ (tee_local $5
+ (tee_local $8
+ (tee_local $6
+ (tee_local $7
+ (get_local $8)
+ )
+ )
+ )
+ )
+ )
+ )
+ )
+ (i32.const -54)
+ )
)
diff --git a/test/passes/ssa.wast b/test/passes/ssa.wast
index e51189b5e..7c8617103 100644
--- a/test/passes/ssa.wast
+++ b/test/passes/ssa.wast
@@ -339,5 +339,49 @@
(br $label$1) ;; back to the top, where we will return the zero
)
)
+ (func $ssa-merge-tricky (result i32)
+ (local $var$0 i32)
+ (local $var$1 i32)
+ (set_local $var$1
+ (tee_local $var$0
+ (i32.const 0) ;; both vars start out identical
+ )
+ )
+ (loop $label$1
+ (if
+ (i32.eqz
+ (get_global $global$0)
+ )
+ (return
+ (i32.const 12345)
+ )
+ )
+ (set_global $global$0
+ (i32.const 0)
+ )
+ (if
+ (i32.eqz
+ (get_local $var$0) ;; check $0 here. this will get a phi var
+ )
+ (br_if $label$1
+ (i32.eqz
+ (tee_local $var$0 ;; set $0 to 1. here the two diverge. for the phi, we'll get a set here and above
+ (i32.const 1)
+ )
+ )
+ )
+ )
+ (br_if $label$1
+ (i32.eqz ;; indeed equal, enter loop again, and then hang prevention kicks in
+ (tee_local $var$1 ;; set them all to 0
+ (tee_local $var$0
+ (get_local $var$1) ;; this must get $1, not the phis, as even though the sets appear in both sources, we only execute 1.
+ )
+ )
+ )
+ )
+ )
+ (i32.const -54)
+ )
)
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-09 08:57:11 +0000