Bug 1627618 - Part 1: Add MAdd with truncate parameter. r=jandem

Later patches will require a constructor with the signature
`MAdd(MDefinition, MDefinition, MIRType)`, which neither sets the truncation
mode nor sets the "commutative" flag. Both things happen with the existing
constructor which has a compatible signature and which is currently called
for the use sites modified in this patch. (The existing constructor is the
one directly appearing before the newly added one.)

The existing constructor defaults to `MDefinition::Truncate` and all callers to
that constructor use the `MIRType::Int32` specialisation. Because all callers
use `MIRType::Int32`, we can omit the type parameter for the new constructor.

The existing constructor is also called from WasmIonCompile, the next part will
handle that caller.

Differential Revision: https://phabricator.services.mozilla.com/D69778

--HG--
extra : moz-landing-system : lando

js/src/jit/AlignmentMaskAnalysis.cpp

@@ -69,7 +69,7 @@ static void AnalyzeAsmHeapAddress(MDefinition* ptr, MIRGraph& graph) {
   // The pattern was matched! Produce the replacement expression.
   MInstruction* and_ = MBitAnd::New(graph.alloc(), op0, rhs, MIRType::Int32);
   ptr->block()->insertBefore(ptr->toBitAnd(), and_);
-  MInstruction* add = MAdd::New(graph.alloc(), and_, op1, MIRType::Int32);
+  auto* add = MAdd::New(graph.alloc(), and_, op1, MDefinition::Truncate);
   ptr->block()->insertBefore(ptr->toBitAnd(), add);
   ptr->replaceAllUsesWith(add);
   ptr->block()->discard(ptr->toBitAnd());

js/src/jit/FoldLinearArithConstants.cpp

@@ -69,8 +69,7 @@ static void AnalyzeAdd(TempAllocator& alloc, MAdd* add) {
   MInstruction* rhs = MConstant::New(alloc, Int32Value(sum.constant));
   add->block()->insertBefore(add, rhs);
 
-  MAdd* addNew =
-      MAdd::New(alloc, sum.term, rhs, MIRType::Int32, add->truncateKind());
+  MAdd* addNew = MAdd::New(alloc, sum.term, rhs, add->truncateKind());
 
   add->replaceAllLiveUsesWith(addNew);
   add->block()->insertBefore(add, addNew);

js/src/jit/IonBuilder.cpp

@@ -6981,7 +6981,7 @@ AbortReasonOr<Ok> IonBuilder::jsop_initelem_inc() {
   MDefinition* id = current->pop();
   MDefinition* obj = current->peek(-1);
 
-  MAdd* nextId = MAdd::New(alloc(), id, constantInt(1), MIRType::Int32);
+  MAdd* nextId = MAdd::New(alloc(), id, constantInt(1), MDefinition::Truncate);
   current->add(nextId);
   current->push(nextId);
 

js/src/jit/MIR.h

@@ -5365,6 +5365,13 @@ class MAdd : public MBinaryArithInstruction {
       setTruncateKind(truncateKind);
       setCommutative();
     }
+
+  MAdd(MDefinition* left, MDefinition* right, TruncateKind truncateKind)
+      : MAdd(left, right) {
+    specialization_ = MIRType::Int32;
+    setResultType(MIRType::Int32);
+    setTruncateKind(truncateKind);
+    setCommutative();
   }
 
  public:

js/src/jit/WarpBuilder.cpp

@@ -2474,7 +2474,7 @@ bool WarpBuilder::build_InitElemInc(BytecodeLocation loc) {
 
   // Push index + 1.
   MConstant* constOne = constant(Int32Value(1));
-  MAdd* nextIndex = MAdd::New(alloc(), index, constOne, MIRType::Int32);
+  MAdd* nextIndex = MAdd::New(alloc(), index, constOne, MDefinition::Truncate);
   current->add(nextIndex);
   current->push(nextIndex);