WIP: Support i64.add128 instruction from Wide Arithmetic Proposal

scripts/gen-s-parser.py

@@ -146,6 +146,8 @@
     ("i64.shr_u",      "makeBinary(BinaryOp::ShrUInt64)"),
     ("i64.rotl",       "makeBinary(BinaryOp::RotLInt64)"),
     ("i64.rotr",       "makeBinary(BinaryOp::RotRInt64)"),
+    ("i64.add128",     "makeWideIntAddSub(WideIntAddSubOp::AddInt128)"),
+    ("i64.sub128",     "makeWideIntAddSub(WideIntAddSubOp::SubInt128)"),
     ("f32.abs",        "makeUnary(UnaryOp::AbsFloat32)"),
     ("f32.neg",        "makeUnary(UnaryOp::NegFloat32)"),
     ("f32.ceil",       "makeUnary(UnaryOp::CeilFloat32)"),

src/gen-s-parser.inc

@@ -3405,12 +3405,23 @@ switch (buf[0]) {
             switch (buf[4]) {
               case 'a': {
                 switch (buf[5]) {
-                  case 'd':
-                    if (op == "i64.add"sv) {
-                      CHECK_ERR(makeBinary(ctx, pos, annotations, BinaryOp::AddInt64));
-                      return Ok{};
+                  case 'd': {
+                    switch (buf[7]) {
+                      case '\0':
+                        if (op == "i64.add"sv) {
+                          CHECK_ERR(makeBinary(ctx, pos, annotations, BinaryOp::AddInt64));
+                          return Ok{};
+                        }
+                        goto parse_error;
+                      case '1':
+                        if (op == "i64.add128"sv) {
+                          CHECK_ERR(makeWideIntAddSub(ctx, pos, annotations, WideIntAddSubOp::AddInt128));
+                          return Ok{};
+                        }
+                        goto parse_error;
+                      default: goto parse_error;
                     }
-                    goto parse_error;
+                  }
                   case 'n':
                     if (op == "i64.and"sv) {
                       CHECK_ERR(makeBinary(ctx, pos, annotations, BinaryOp::AndInt64));

src/interpreter/interpreter.cpp

@@ -217,6 +217,28 @@ struct ExpressionInterpreter : OverriddenVisitor<ExpressionInterpreter, Flow> {
     }
   }
   Flow visitSelect(Select* curr) { WASM_UNREACHABLE("TODO"); }
+  Flow visitWideIntAddSub(WideIntAddSub* curr) {
+    if (curr->op == AddInt128 || curr->op == SubInt128) {
+      uint64_t highRHS = pop().geti64();
+      uint64_t lowRHS = pop().geti64();
+      uint64_t highLHS = pop().geti64();
+      uint64_t lowLHS = pop().geti64();
+
+      uint64_t lowRes, highRes;
+      if (curr->op == AddInt128) {
+        lowRes = lowLHS + lowRHS;
+        highRes = highLHS + highRHS + (lowRes < lowLHS);
+      } else {
+        lowRes = lowLHS - lowRHS;
+        highRes = highLHS - highRHS - (lowLHS < lowRHS);
+      }
+
+      push(Literal(lowRes));
+      push(Literal(highRes));
+      return {};
+    }
+    WASM_UNREACHABLE("TODO");
+  }
   Flow visitDrop(Drop* curr) { WASM_UNREACHABLE("TODO"); }
   Flow visitReturn(Return* curr) { WASM_UNREACHABLE("TODO"); }
   Flow visitMemorySize(MemorySize* curr) { WASM_UNREACHABLE("TODO"); }

src/ir/ReFinalize.cpp

@@ -109,6 +109,7 @@ void ReFinalize::visitMemoryFill(MemoryFill* curr) { curr->finalize(); }
 void ReFinalize::visitConst(Const* curr) { curr->finalize(); }
 void ReFinalize::visitUnary(Unary* curr) { curr->finalize(); }
 void ReFinalize::visitBinary(Binary* curr) { curr->finalize(); }
+void ReFinalize::visitWideIntAddSub(WideIntAddSub* curr) { curr->finalize(); }
 void ReFinalize::visitSelect(Select* curr) { curr->finalize(); }
 void ReFinalize::visitDrop(Drop* curr) { curr->finalize(); }
 void ReFinalize::visitReturn(Return* curr) { curr->finalize(); }

src/ir/child-typer.h

@@ -703,6 +703,13 @@ template<typename Subtype> struct ChildTyper : OverriddenVisitor<Subtype> {
     }
   }
 
+  void visitWideIntAddSub(WideIntAddSub* curr) {
+    note(&curr->leftLow, Type::i64);
+    note(&curr->leftHigh, Type::i64);
+    note(&curr->rightLow, Type::i64);
+    note(&curr->rightHigh, Type::i64);
+  }
+
   void visitSelect(Select* curr, std::optional<Type> type = std::nullopt) {
     if (type) {
       note(&curr->ifTrue, *type);

src/ir/cost.h

@@ -573,6 +573,10 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, CostType> {
     }
     return ret + visit(curr->left) + visit(curr->right);
   }
+  CostType visitWideIntAddSub(WideIntAddSub* curr) {
+    return 1 + visit(curr->leftLow) + visit(curr->leftHigh) +
+           visit(curr->rightLow) + visit(curr->rightHigh);
+  }
   CostType visitSelect(Select* curr) {
     return 1 + visit(curr->condition) + visit(curr->ifTrue) +
            visit(curr->ifFalse);

src/ir/effects.h

@@ -945,6 +945,7 @@ class EffectAnalyzer {
         }
       }
     }
+    void visitWideIntAddSub(WideIntAddSub* curr) {}
     void visitSelect(Select* curr) {}
     void visitDrop(Drop* curr) {}
     void visitReturn(Return* curr) { parent.branchesOut = true; }

src/ir/possible-contents.cpp

@@ -634,6 +634,7 @@ struct InfoCollector
     addRoot(curr);
   }
   void visitBinary(Binary* curr) { addRoot(curr); }
+  void visitWideIntAddSub(WideIntAddSub* curr) { addRoot(curr); }
   void visitSelect(Select* curr) {
     receiveChildValue(curr->ifTrue, curr);
     receiveChildValue(curr->ifFalse, curr);

src/ir/subtype-exprs.h

@@ -213,6 +213,7 @@ struct SubtypingDiscoverer : public OverriddenVisitor<SubType> {
   void visitConst(Const* curr) {}
   void visitUnary(Unary* curr) {}
   void visitBinary(Binary* curr) {}
+  void visitWideIntAddSub(WideIntAddSub* curr) {}
   void visitSelect(Select* curr) {
     self()->noteSubtype(curr->ifTrue, curr);
     self()->noteSubtype(curr->ifFalse, curr);

src/parser/contexts.h

@@ -476,6 +476,12 @@ struct NullInstrParserCtx {
   Result<> makeBinary(Index, const std::vector<Annotation>&, BinaryOp) {
     return Ok{};
   }
+  Result<> makeWideIntAddSub(Index,
+                             const std::vector<Annotation>&,
+                             WideIntAddSubOp) {
+    return Ok{};
+  }
+
   Result<> makeUnary(Index, const std::vector<Annotation>&, UnaryOp) {
     return Ok{};
   }
@@ -2159,6 +2165,12 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx>, AnnotationParserCtx {
     return withLoc(pos, irBuilder.makeBinary(op));
   }
 
+  Result<> makeWideIntAddSub(Index pos,
+                             const std::vector<Annotation>& annotations,
+                             WideIntAddSubOp op) {
+    return withLoc(pos, irBuilder.makeWideIntAddSub(op));
+  }
+
   Result<>
   makeUnary(Index pos, const std::vector<Annotation>& annotations, UnaryOp op) {
     return withLoc(pos, irBuilder.makeUnary(op));

src/parser/parsers.h

@@ -90,6 +90,10 @@ template<typename Ctx>
 Result<> makeNop(Ctx&, Index, const std::vector<Annotation>&);
 template<typename Ctx>
 Result<> makeBinary(Ctx&, Index, const std::vector<Annotation>&, BinaryOp op);
+template<typename Ctx>
+Result<>
+makeWideIntAddSub(Ctx&, Index, const std::vector<Annotation>&, WideIntAddSubOp op);
+
 template<typename Ctx>
 Result<> makeUnary(Ctx&, Index, const std::vector<Annotation>&, UnaryOp op);
 template<typename Ctx>
@@ -1592,6 +1596,14 @@ Result<> makeBinary(Ctx& ctx,
   return ctx.makeBinary(pos, annotations, op);
 }
 
+template<typename Ctx>
+Result<> makeWideIntAddSub(Ctx& ctx,
+                           Index pos,
+                           const std::vector<Annotation>& annotations,
+                           WideIntAddSubOp op) {
+  return ctx.makeWideIntAddSub(pos, annotations, op);
+}
+
 template<typename Ctx>
 Result<> makeUnary(Ctx& ctx,
                    Index pos,

src/passes/I64ToI32Lowering.cpp

@@ -1553,6 +1553,10 @@ struct I64ToI32Lowering : public WalkerPass<PostWalker<I64ToI32Lowering>> {
     }
   }
 
+  void visitWideIntAddSub(WideIntAddSub* curr) {
+    WASM_UNREACHABLE("TODO: wide arithmetic lowering");
+  }
+
   void visitSelect(Select* curr) {
     if (handleUnreachable(curr)) {
       return;

src/passes/Precompute.cpp

@@ -282,6 +282,10 @@ class PrecomputingExpressionRunner
     return Flow(NONCONSTANT_FLOW);
   }
 
+  Flow visitWideIntAddSub(WideIntAddSub* curr) {
+    return Super::visitWideIntAddSub(curr);
+  }
+
   Flow visitStringEncode(StringEncode* curr) {
     // string.encode_wtf16_array is effectively an Array write operation, so
     // just like ArraySet and ArrayCopy above we must mark it as disallowed

src/passes/Print.cpp

@@ -2025,6 +2025,20 @@ struct PrintExpressionContents
     }
     restoreNormalColor(o);
   }
+  void visitWideIntAddSub(WideIntAddSub* curr) {
+    prepareColor(o);
+    switch (curr->op) {
+      case AddInt128:
+        o << "i64.add128";
+        break;
+      case SubInt128:
+        o << "i64.sub128";
+        break;
+      default:
+        WASM_UNREACHABLE("invalid wide int binary op");
+    }
+    restoreNormalColor(o);
+  }
   void visitSelect(Select* curr) {
     prepareColor(o) << "select";
     restoreNormalColor(o);

src/passes/TypeGeneralizing.cpp

@@ -433,6 +433,7 @@ struct TransferFn : OverriddenVisitor<TransferFn> {
   void visitConst(Const* curr) {}
   void visitUnary(Unary* curr) {}
   void visitBinary(Binary* curr) {}
+  void visitWideIntAddSub(WideIntAddSub* curr) {}
 
   void visitSelect(Select* curr) {
     if (curr->type.isRef()) {

src/wasm-binary.h

@@ -1136,6 +1136,11 @@ enum ASTNodes {
   MemoryCopy = 0x0a,
   MemoryFill = 0x0b,
 
+  // wide arithmetic opcodes
+
+  I64Add128 = 0x13,
+  I64Sub128 = 0x14,
+
   // reference types opcodes
 
   TableGrow = 0x0f,

src/wasm-builder.h

@@ -660,6 +660,20 @@ class Builder {
     ret->finalize();
     return ret;
   }
+  WideIntAddSub* makeWideIntAddSub(WideIntAddSubOp op,
+                                   Expression* leftLow,
+                                   Expression* leftHigh,
+                                   Expression* rightLow,
+                                   Expression* rightHigh) {
+    auto* ret = wasm.allocator.alloc<WideIntAddSub>();
+    ret->op = op;
+    ret->leftLow = leftLow;
+    ret->leftHigh = leftHigh;
+    ret->rightLow = rightLow;
+    ret->rightHigh = rightHigh;
+    ret->finalize();
+    return ret;
+  }
   Select*
   makeSelect(Expression* condition, Expression* ifTrue, Expression* ifFalse) {
     auto* ret = wasm.allocator.alloc<Select>();

src/wasm-delegations-fields.def

@@ -931,6 +931,13 @@ DELEGATE_FIELD_IMMEDIATE_TYPED_CHILD(StructNotify, ref)
 DELEGATE_FIELD_INT(StructNotify, index)
 DELEGATE_FIELD_CASE_END(StructNotify)
 
+DELEGATE_FIELD_CASE_START(WideIntAddSub)
+DELEGATE_FIELD_INT(WideIntAddSub, op)
+DELEGATE_FIELD_CHILD(WideIntAddSub, leftLow)
+DELEGATE_FIELD_CHILD(WideIntAddSub, leftHigh)
+DELEGATE_FIELD_CHILD(WideIntAddSub, rightLow)
+DELEGATE_FIELD_CHILD(WideIntAddSub, rightHigh)
+DELEGATE_FIELD_CASE_END(WideIntAddSub)
 
 DELEGATE_FIELD_MAIN_END
 

src/wasm-delegations.def

@@ -119,5 +119,6 @@ DELEGATE(ResumeThrow);
 DELEGATE(StackSwitch);
 DELEGATE(StructWait);
 DELEGATE(StructNotify);
+DELEGATE(WideIntAddSub);
 
 #undef DELEGATE

src/wasm-interpreter.h

@@ -1797,6 +1797,33 @@ class ExpressionRunner : public OverriddenVisitor<SubType, Flow> {
     VISIT(condition, curr->condition)
     return condition.getSingleValue().geti32() ? ifTrue : ifFalse; // ;-)
   }
+  Flow visitWideIntAddSub(WideIntAddSub* curr) {
+    VISIT(leftLow, curr->leftLow);
+    VISIT(leftHigh, curr->leftHigh);
+    VISIT(rightLow, curr->rightLow);
+    VISIT(rightHigh, curr->rightHigh);
+    if (curr->op == AddInt128 || curr->op == SubInt128) {
+      uint64_t lowLHS = leftLow.getSingleValue().geti64();
+      uint64_t highLHS = leftHigh.getSingleValue().geti64();
+      uint64_t lowRHS = rightLow.getSingleValue().geti64();
+      uint64_t highRHS = rightHigh.getSingleValue().geti64();
+
+      uint64_t lowRes, highRes;
+      if (curr->op == AddInt128) {
+        lowRes = lowLHS + lowRHS;
+        highRes = highLHS + highRHS + (lowRes < lowLHS);
+      } else {
+        lowRes = lowLHS - lowRHS;
+        highRes = highLHS - highRHS - (lowLHS < lowRHS);
+      }
+
+      Literals results;
+      results.push_back(Literal(lowRes));
+      results.push_back(Literal(highRes));
+      return results;
+    }
+    WASM_UNREACHABLE("invalid wide int binary op");
+  }
   Flow visitDrop(Drop* curr) {
     VISIT(value, curr->value)
     return Flow();
@@ -3047,6 +3074,9 @@ class ConstantExpressionRunner : public ExpressionRunner<SubType> {
   Flow visitAtomicCmpxchg(AtomicCmpxchg* curr) {
     return Flow(NONCONSTANT_FLOW);
   }
+  Flow visitWideIntAddSub(WideIntAddSub* curr) {
+    return ExpressionRunner<SubType>::visitWideIntAddSub(curr);
+  }
   Flow visitAtomicWait(AtomicWait* curr) { return Flow(NONCONSTANT_FLOW); }
   Flow visitAtomicNotify(AtomicNotify* curr) { return Flow(NONCONSTANT_FLOW); }
   Flow visitStructWait(StructWait* curr) { return Flow(NONCONSTANT_FLOW); }

src/wasm-ir-builder.h

@@ -190,6 +190,7 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {
   Result<> makeConst(Literal val);
   Result<> makeUnary(UnaryOp op);
   Result<> makeBinary(BinaryOp op);
+  Result<> makeWideIntAddSub(WideIntAddSubOp op);
   Result<> makeSelect(std::optional<Type> type = std::nullopt);
   Result<> makeDrop();
   Result<> makeReturn();

src/wasm.h

@@ -638,6 +638,11 @@ enum StringEqOp {
   StringEqCompare,
 };
 
+enum WideIntAddSubOp {
+  AddInt128,
+  SubInt128,
+};
+
 //
 // Expressions
 //
@@ -767,6 +772,7 @@ class Expression {
     StackSwitchId,
     StructWaitId,
     StructNotifyId,
+    WideIntAddSubId,
     NumExpressionIds
   };
   Id _id;
@@ -1298,6 +1304,20 @@ class Binary : public SpecificExpression<Expression::BinaryId> {
   void finalize();
 };
 
+class WideIntAddSub : public SpecificExpression<Expression::WideIntAddSubId> {
+public:
+  WideIntAddSub() = default;
+  WideIntAddSub(MixedArena& allocator) {}
+
+  WideIntAddSubOp op;
+  Expression* leftLow;
+  Expression* leftHigh;
+  Expression* rightLow;
+  Expression* rightHigh;
+
+  void finalize();
+};
+
 class Select : public SpecificExpression<Expression::SelectId> {
 public:
   Select() = default;

src/wasm/wasm-binary.cpp

@@ -3998,6 +3998,11 @@ Result<> WasmBinaryReader::readInst() {
         }
         case BinaryConsts::MemoryFill:
           return builder.makeMemoryFill(getMemoryName(getU32LEB()));
+        case BinaryConsts::I64Add128:
+          return builder.makeWideIntAddSub(AddInt128);
+        case BinaryConsts::I64Sub128:
+          return builder.makeWideIntAddSub(SubInt128);
+
         case BinaryConsts::TableSize:
           return builder.makeTableSize(getTableName(getU32LEB()));
         case BinaryConsts::TableGrow: