From 6759371b5239efa3daa9d988455abdd14a8b18ca Mon Sep 17 00:00:00 2001
From: Thomas Lively <7121787+tlively@users.noreply.github.com>
Date: Thu, 4 Aug 2022 17:05:54 -0700
Subject: Remove RTTs (#4848)

RTTs were removed from the GC spec and if they are added back in in the future,
they will be heap types rather than value types as in our implementation.
Updating our implementation to have RTTs be heap types would have been more work
than deleting them for questionable benefit since we don't know how long it will
be before they are specced again.
---
 src/passes/Print.cpp | 93 ++++++++++------------------------------------------
 1 file changed, 18 insertions(+), 75 deletions(-)

(limited to 'src/passes/Print.cpp')

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 962246569..62dc58c48 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -152,7 +152,6 @@ struct TypeNamePrinter {
   void print(const Signature& sig);
   void print(const Struct& struct_);
   void print(const Array& array);
-  void print(const Rtt& rtt);
 
   // FIXME: This hard limit on how many times we call print() avoids extremely
   //        large outputs, which can be inconveniently large in some cases, but
@@ -179,8 +178,6 @@ void TypeNamePrinter::print(Type type) {
     os << type;
   } else if (type.isTuple()) {
     print(type.getTuple());
-  } else if (type.isRtt()) {
-    print(type.getRtt());
   } else if (type.isRef()) {
     if (!maybePrintRefShorthand(os, type)) {
       os << "ref";
@@ -301,14 +298,6 @@ void TypeNamePrinter::print(const Array& array) {
   os << ']';
 }
 
-void TypeNamePrinter::print(const Rtt& rtt) {
-  os << "rtt_";
-  if (rtt.hasDepth()) {
-    os << rtt.depth << '_';
-  }
-  print(rtt.heapType);
-}
-
 } // anonymous namespace
 
 static std::ostream& printType(std::ostream& o, Type type, Module* wasm) {
@@ -323,14 +312,6 @@ static std::ostream& printType(std::ostream& o, Type type, Module* wasm) {
       sep = " ";
     }
     o << ')';
-  } else if (type.isRtt()) {
-    auto rtt = type.getRtt();
-    o << "(rtt ";
-    if (rtt.hasDepth()) {
-      o << rtt.depth << ' ';
-    }
-    TypeNamePrinter(o, wasm).print(rtt.heapType);
-    o << ')';
   } else if (type.isRef()) {
     if (!maybePrintRefShorthand(o, type)) {
       o << "(ref ";
@@ -2027,24 +2008,17 @@ struct PrintExpressionContents
     }
   }
   void visitRefTest(RefTest* curr) {
-    if (curr->rtt) {
-      printMedium(o, "ref.test");
-    } else {
-      printMedium(o, "ref.test_static ");
-      printHeapType(o, curr->intendedType, wasm);
-    }
+    printMedium(o, "ref.test_static ");
+    printHeapType(o, curr->intendedType, wasm);
   }
+
   void visitRefCast(RefCast* curr) {
-    if (curr->rtt) {
-      printMedium(o, "ref.cast");
+    if (curr->safety == RefCast::Unsafe) {
+      printMedium(o, "ref.cast_nop_static ");
     } else {
-      if (curr->safety == RefCast::Unsafe) {
-        printMedium(o, "ref.cast_nop_static ");
-      } else {
-        printMedium(o, "ref.cast_static ");
-      }
-      printHeapType(o, curr->intendedType, wasm);
+      printMedium(o, "ref.cast_static ");
     }
+    printHeapType(o, curr->intendedType, wasm);
   }
   void visitBrOn(BrOn* curr) {
     switch (curr->op) {
@@ -2055,27 +2029,17 @@ struct PrintExpressionContents
         printMedium(o, "br_on_non_null ");
         break;
       case BrOnCast:
-        if (curr->rtt) {
-          printMedium(o, "br_on_cast ");
-        } else {
-          printMedium(o, "br_on_cast_static ");
-          printName(curr->name, o);
-          o << ' ';
-          printHeapType(o, curr->intendedType, wasm);
-          return;
-        }
-        break;
+        printMedium(o, "br_on_cast_static ");
+        printName(curr->name, o);
+        o << ' ';
+        printHeapType(o, curr->intendedType, wasm);
+        return;
       case BrOnCastFail:
-        if (curr->rtt) {
-          printMedium(o, "br_on_cast_fail ");
-        } else {
-          printMedium(o, "br_on_cast_static_fail ");
-          printName(curr->name, o);
-          o << ' ';
-          printHeapType(o, curr->intendedType, wasm);
-          return;
-        }
-        break;
+        printMedium(o, "br_on_cast_static_fail ");
+        printName(curr->name, o);
+        o << ' ';
+        printHeapType(o, curr->intendedType, wasm);
+        return;
       case BrOnFunc:
         printMedium(o, "br_on_func ");
         break;
@@ -2099,18 +2063,6 @@ struct PrintExpressionContents
     }
     printName(curr->name, o);
   }
-  void visitRttCanon(RttCanon* curr) {
-    printMedium(o, "rtt.canon ");
-    TypeNamePrinter(o, wasm).print(curr->type.getRtt().heapType);
-  }
-  void visitRttSub(RttSub* curr) {
-    if (curr->fresh) {
-      printMedium(o, "rtt.fresh_sub ");
-    } else {
-      printMedium(o, "rtt.sub ");
-    }
-    TypeNamePrinter(o, wasm).print(curr->type.getRtt().heapType);
-  }
 
   // If we cannot print a valid unreachable instruction (say, a struct.get,
   // where if the ref is unreachable, we don't know what heap type to print),
@@ -2135,9 +2087,6 @@ struct PrintExpressionContents
     if (curr->isWithDefault()) {
       printMedium(o, "_default");
     }
-    if (curr->rtt) {
-      printMedium(o, "_with_rtt");
-    }
     o << ' ';
     TypeNamePrinter(o, wasm).print(curr->type.getHeapType());
   }
@@ -2188,9 +2137,6 @@ struct PrintExpressionContents
     if (curr->isWithDefault()) {
       printMedium(o, "_default");
     }
-    if (curr->rtt) {
-      printMedium(o, "_with_rtt");
-    }
     o << ' ';
     TypeNamePrinter(o, wasm).print(curr->type.getHeapType());
   }
@@ -2198,10 +2144,7 @@ struct PrintExpressionContents
     if (printUnreachableReplacement(curr)) {
       return;
     }
-    printMedium(o, "array.init");
-    if (!curr->rtt) {
-      printMedium(o, "_static");
-    }
+    printMedium(o, "array.init_static");
     o << ' ';
     TypeNamePrinter(o, wasm).print(curr->type.getHeapType());
   }
-- 
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