[wasm] Use branch hint for the -1 check in I(32|64)Div.

src/compiler/wasm-compiler.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/wasm-compiler.h"
 
 #include <memory>
 
 #include "src/isolate-inl.h"
 
@@ skipping 1778 matching lines @@
   *control_ = merge;
   *effect_ = effect_merge;
   return value_i32;
 }
 
 Node* WasmGraphBuilder::BuildI32DivS(Node* left, Node* right,
                                      wasm::WasmCodePosition position) {
   MachineOperatorBuilder* m = jsgraph()->machine();
   trap_->ZeroCheck32(wasm::kTrapDivByZero, right, position);
   Node* before = *control_;
-  Node* denom_is_m1;
-  Node* denom_is_not_m1;
-  Branch(
-      graph()->NewNode(m->Word32Equal(), right, jsgraph()->Int32Constant(-1)),
-      &denom_is_m1, &denom_is_not_m1);
+  Node* is_denom_m1 =

[titzer, 2016/10/17 13:44:16]

Can you add a branch hint to the old method so that we don't need to break it
down to individual nodes here?

+      graph()->NewNode(m->Word32Equal(), right, jsgraph()->Int32Constant(-1));
+  Node* branch = graph()->NewNode(
+      jsgraph()->common()->Branch(BranchHint::kFalse), is_denom_m1, *control_);
+  Node* denom_is_m1 = graph()->NewNode(jsgraph()->common()->IfTrue(), branch);
+  Node* denom_is_not_m1 =
+      graph()->NewNode(jsgraph()->common()->IfFalse(), branch);
   *control_ = denom_is_m1;
   trap_->TrapIfEq32(wasm::kTrapDivUnrepresentable, left, kMinInt, position);
   if (*control_ != denom_is_m1) {
     *control_ = graph()->NewNode(jsgraph()->common()->Merge(2), denom_is_not_m1,
                                  *control_);
   } else {
     *control_ = before;
   }
   return graph()->NewNode(m->Int32Div(), left, right, *control_);
 }
@@ skipping 110 matching lines @@
       BranchHint::kFalse);
 
   Node* rem = graph()->NewNode(jsgraph()->machine()->Uint32Mod(), left, right,
                                z.if_false);
   return z.Phi(MachineRepresentation::kWord32, jsgraph()->Int32Constant(0),
                rem);
 }
 
 Node* WasmGraphBuilder::BuildI64DivS(Node* left, Node* right,
                                      wasm::WasmCodePosition position) {
-  if (jsgraph()->machine()->Is32()) {
+  MachineOperatorBuilder* m = jsgraph()->machine();
+  if (m->Is32()) {
     return BuildDiv64Call(
         left, right, ExternalReference::wasm_int64_div(jsgraph()->isolate()),
         MachineType::Int64(), wasm::kTrapDivByZero, position);
   }
   trap_->ZeroCheck64(wasm::kTrapDivByZero, right, position);
   Node* before = *control_;
-  Node* denom_is_m1;
-  Node* denom_is_not_m1;
-  Branch(graph()->NewNode(jsgraph()->machine()->Word64Equal(), right,
-                          jsgraph()->Int64Constant(-1)),
-         &denom_is_m1, &denom_is_not_m1);
+  Node* is_denom_m1 =
+      graph()->NewNode(m->Word64Equal(), right, jsgraph()->Int64Constant(-1));
+  Node* branch = graph()->NewNode(
+      jsgraph()->common()->Branch(BranchHint::kFalse), is_denom_m1, *control_);
+  Node* denom_is_m1 = graph()->NewNode(jsgraph()->common()->IfTrue(), branch);
+  Node* denom_is_not_m1 =
+      graph()->NewNode(jsgraph()->common()->IfFalse(), branch);
   *control_ = denom_is_m1;
   trap_->TrapIfEq64(wasm::kTrapDivUnrepresentable, left,
                     std::numeric_limits<int64_t>::min(), position);
   if (*control_ != denom_is_m1) {
     *control_ = graph()->NewNode(jsgraph()->common()->Merge(2), denom_is_not_m1,
                                  *control_);
   } else {
     *control_ = before;
   }
   return graph()->NewNode(jsgraph()->machine()->Int64Div(), left, right,
@@ skipping 1460 matching lines @@
                             function_->code_start_offset),
            compile_ms);
   }
 
   return code;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8