From ca27f40a2f1070a16ee7c0efc18ff35d342d8027 Mon Sep 17 00:00:00 2001
From: Thomas Lively <7121787+tlively@users.noreply.github.com>
Date: Thu, 1 Jul 2021 01:56:23 +0000
Subject: Preserve Function HeapTypes (#3952)

When using nominal types, func.ref of two functions with identical signatures
but different HeapTypes will yield different types. To preserve these semantics,
Functions need to track their HeapTypes, not just their Signatures.

This PR replaces the Signature field in Function with a HeapType field and adds
new utility methods to make it almost as simple to update and query the function
HeapType as it was to update and query the Function Signature.
---
 src/ir/module-splitting.cpp | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

(limited to 'src/ir/module-splitting.cpp')

diff --git a/src/ir/module-splitting.cpp b/src/ir/module-splitting.cpp
index 62c10222a..2ef9f505d 100644
--- a/src/ir/module-splitting.cpp
+++ b/src/ir/module-splitting.cpp
@@ -122,7 +122,7 @@ struct TableSlotManager {
   ElementSegment* makeElementSegment();
 
   // Returns the table index for `func`, allocating a new index if necessary.
-  Slot getSlot(Name func, Signature sig);
+  Slot getSlot(Name func, HeapType type);
   void addSlot(Name func, Slot slot);
 };
 
@@ -209,7 +209,7 @@ ElementSegment* TableSlotManager::makeElementSegment() {
     Builder(module).makeConst(int32_t(0))));
 }
 
-TableSlotManager::Slot TableSlotManager::getSlot(Name func, Signature sig) {
+TableSlotManager::Slot TableSlotManager::getSlot(Name func, HeapType type) {
   auto slotIt = funcIndices.find(func);
   if (slotIt != funcIndices.end()) {
     return slotIt->second;
@@ -237,7 +237,7 @@ TableSlotManager::Slot TableSlotManager::getSlot(Name func, Signature sig) {
                   activeBase.index + Index(activeSegment->data.size())};
 
   Builder builder(module);
-  activeSegment->data.push_back(builder.makeRefFunc(func, sig));
+  activeSegment->data.push_back(builder.makeRefFunc(func, type));
 
   addSlot(func, newSlot);
   if (activeTable->initial <= newSlot.index) {
@@ -365,7 +365,7 @@ void ModuleSplitter::exportImportFunction(Name funcName) {
   // module.
   if (secondary.getFunctionOrNull(funcName) == nullptr) {
     auto func =
-      Builder::makeFunction(funcName, primary.getFunction(funcName)->sig, {});
+      Builder::makeFunction(funcName, primary.getFunction(funcName)->type, {});
     func->module = config.importNamespace;
     func->base = exportName;
     secondary.addFunction(std::move(func));
@@ -399,14 +399,15 @@ void ModuleSplitter::thunkExportedSecondaryFunctions() {
       continue;
     }
     auto* func = primary.addFunction(Builder::makeFunction(
-      secondaryFunc, secondary.getFunction(secondaryFunc)->sig, {}));
+      secondaryFunc, secondary.getFunction(secondaryFunc)->type, {}));
     std::vector<Expression*> args;
-    for (size_t i = 0, size = func->sig.params.size(); i < size; ++i) {
-      args.push_back(builder.makeLocalGet(i, func->sig.params[i]));
+    Type params = func->getParams();
+    for (size_t i = 0, size = params.size(); i < size; ++i) {
+      args.push_back(builder.makeLocalGet(i, params[i]));
     }
-    auto tableSlot = tableManager.getSlot(secondaryFunc, func->sig);
+    auto tableSlot = tableManager.getSlot(secondaryFunc, func->type);
     func->body = builder.makeCallIndirect(
-      tableSlot.tableName, tableSlot.makeExpr(primary), args, func->sig);
+      tableSlot.tableName, tableSlot.makeExpr(primary), args, func->getSig());
   }
 }
 
@@ -425,12 +426,12 @@ void ModuleSplitter::indirectCallsToSecondaryFunctions() {
         return;
       }
       auto* func = parent.secondary.getFunction(curr->target);
-      auto tableSlot = parent.tableManager.getSlot(curr->target, func->sig);
+      auto tableSlot = parent.tableManager.getSlot(curr->target, func->type);
       replaceCurrent(
         builder.makeCallIndirect(tableSlot.tableName,
                                  tableSlot.makeExpr(parent.primary),
                                  curr->operands,
-                                 func->sig,
+                                 func->getSig(),
                                  curr->isReturn));
     }
     void visitRefFunc(RefFunc* curr) {
@@ -496,7 +497,7 @@ void ModuleSplitter::setupTablePatching() {
         primary,
         std::string("placeholder_") + std::string(placeholder->base.c_str()));
       placeholder->hasExplicitName = false;
-      placeholder->sig = secondaryFunc->sig;
+      placeholder->type = secondaryFunc->type;
       elem = placeholder->name;
       primary.addFunction(std::move(placeholder));
     }
@@ -535,7 +536,7 @@ void ModuleSplitter::setupTablePatching() {
       if (replacement->first == i) {
         // primarySeg->data[i] is a placeholder, so use the secondary function.
         auto* func = replacement->second;
-        auto* ref = Builder(secondary).makeRefFunc(func->name, func->sig);
+        auto* ref = Builder(secondary).makeRefFunc(func->name, func->type);
         secondaryElems.push_back(ref);
         ++replacement;
       } else if (auto* get = primarySeg->data[i]->dynCast<RefFunc>()) {
@@ -574,7 +575,7 @@ void ModuleSplitter::setupTablePatching() {
       currData.clear();
     }
     auto* func = curr->second;
-    currData.push_back(Builder(secondary).makeRefFunc(func->name, func->sig));
+    currData.push_back(Builder(secondary).makeRefFunc(func->name, func->type));
   }
   if (currData.size()) {
     finishSegment();
-- 
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