[Wasm GC] Fix nondeterminism in SignaturePruning (#5608)

The order of iteration on sigFuncs there can matter, as each time we
prune we end up changing things that can affect other prunings (specifically,
ParamUtils::removeParameter can decide that it can't remove a parameter
based on the effects on arguments, and current limitations in how we handle
that; and pruning can affect effects).

1 files changed, 8 insertions, 3 deletions

diff --git a/src/passes/SignaturePruning.cpp b/src/passes/SignaturePruning.cpp
index 292feeca5..cd3f4abf6 100644
--- a/src/passes/SignaturePruning.cpp
+++ b/src/passes/SignaturePruning.cpp
@@ -35,6 +35,7 @@
 #include "ir/type-updating.h"
 #include "param-utils.h"
 #include "pass.h"
+#include "support/insert_ordered.h"
 #include "support/sorted_vector.h"
 #include "wasm-type.h"
 #include "wasm.h"
@@ -98,10 +99,14 @@ struct SignaturePruning : public Pass {
     std::unordered_map<HeapType, Info> allInfo;
 
     // Map heap types to all functions with that type.
-    std::unordered_map<HeapType, std::vector<Function*>> sigFuncs;
+    InsertOrderedMap<HeapType, std::vector<Function*>> sigFuncs;
+
+    // Combine all the information we gathered into that map, iterating in a
+    // deterministic order as we build up vectors where the order matters.
+    for (auto& f : module->functions) {
+      auto* func = f.get();
+      auto& info = analysis.map[func];
 
-    // Combine all the information we gathered into that map.
-    for (auto& [func, info] : analysis.map) {
       // For direct calls, add each call to the type of the function being
       // called.
       for (auto* call : info.calls) {