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

R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2413343002
Cr-Commit-Position: refs/heads/master@{#40400}

src/compiler/wasm-compiler.cc

@@ -990,16 +990,36 @@ Node* WasmGraphBuilder::HeapConstant(Handle<HeapObject> value) {
   return jsgraph()->HeapConstant(value);
 }
 
-Node* WasmGraphBuilder::Branch(Node* cond, Node** true_node,
-                               Node** false_node) {
+namespace {
+Node* Branch(JSGraph* jsgraph, Node* cond, Node** true_node, Node** false_node,
+             Node* control, BranchHint hint) {
   DCHECK_NOT_NULL(cond);
-  DCHECK_NOT_NULL(*control_);
+  DCHECK_NOT_NULL(control);
   Node* branch =
-      graph()->NewNode(jsgraph()->common()->Branch(), cond, *control_);
-  *true_node = graph()->NewNode(jsgraph()->common()->IfTrue(), branch);
-  *false_node = graph()->NewNode(jsgraph()->common()->IfFalse(), branch);
+      jsgraph->graph()->NewNode(jsgraph->common()->Branch(hint), cond, control);
+  *true_node = jsgraph->graph()->NewNode(jsgraph->common()->IfTrue(), branch);
+  *false_node = jsgraph->graph()->NewNode(jsgraph->common()->IfFalse(), branch);
   return branch;
 }
+}  // namespace
+
+Node* WasmGraphBuilder::BranchNoHint(Node* cond, Node** true_node,
+                                     Node** false_node) {
+  return Branch(jsgraph(), cond, true_node, false_node, *control_,
+                BranchHint::kNone);
+}
+
+Node* WasmGraphBuilder::BranchExpectTrue(Node* cond, Node** true_node,
+                                         Node** false_node) {
+  return Branch(jsgraph(), cond, true_node, false_node, *control_,
+                BranchHint::kTrue);
+}
+
+Node* WasmGraphBuilder::BranchExpectFalse(Node* cond, Node** true_node,
+                                          Node** false_node) {
+  return Branch(jsgraph(), cond, true_node, false_node, *control_,
+                BranchHint::kFalse);
+}
 
 Node* WasmGraphBuilder::Switch(unsigned count, Node* key) {
   return graph()->NewNode(jsgraph()->common()->Switch(count), key, *control_);
@@ -1758,7 +1778,7 @@ Node* WasmGraphBuilder::Catch(Node* input, wasm::WasmCodePosition position) {
 
   Node* is_smi;
   Node* is_heap;
-  Branch(BuildTestNotSmi(value), &is_heap, &is_smi);
+  BranchExpectFalse(BuildTestNotSmi(value), &is_heap, &is_smi);
 
   // is_smi
   Node* smi_i32 = BuildChangeSmiToInt32(value);
@@ -1798,7 +1818,7 @@ Node* WasmGraphBuilder::BuildI32DivS(Node* left, Node* right,
   Node* before = *control_;
   Node* denom_is_m1;
   Node* denom_is_not_m1;
-  Branch(
+  BranchExpectFalse(
       graph()->NewNode(m->Word32Equal(), right, jsgraph()->Int32Constant(-1)),
       &denom_is_m1, &denom_is_not_m1);
   *control_ = denom_is_m1;
@@ -1940,7 +1960,7 @@ Node* WasmGraphBuilder::BuildI64DivS(Node* left, Node* right,
   Node* before = *control_;
   Node* denom_is_m1;
   Node* denom_is_not_m1;
-  Branch(graph()->NewNode(jsgraph()->machine()->Word64Equal(), right,
+  BranchExpectFalse(graph()->NewNode(jsgraph()->machine()->Word64Equal(), right,
                                      jsgraph()->Int64Constant(-1)),
                     &denom_is_m1, &denom_is_not_m1);
   *control_ = denom_is_m1;

src/compiler/wasm-compiler.h

@@ -148,7 +148,10 @@ class WasmGraphBuilder {
   //-----------------------------------------------------------------------
   // Operations that read and/or write {control} and {effect}.
   //-----------------------------------------------------------------------
-  Node* Branch(Node* cond, Node** true_node, Node** false_node);
+  Node* BranchNoHint(Node* cond, Node** true_node, Node** false_node);
+  Node* BranchExpectTrue(Node* cond, Node** true_node, Node** false_node);
+  Node* BranchExpectFalse(Node* cond, Node** true_node, Node** false_node);
+
   Node* Switch(unsigned count, Node* key);
   Node* IfValue(int32_t value, Node* sw);
   Node* IfDefault(Node* sw);

src/wasm/ast-decoder.cc

@@ -698,7 +698,7 @@ class WasmFullDecoder : public WasmDecoder {
             Value cond = Pop(0, kAstI32);
             TFNode* if_true = nullptr;
             TFNode* if_false = nullptr;
-            BUILD(Branch, cond.node, &if_true, &if_false);
+            BUILD(BranchNoHint, cond.node, &if_true, &if_false);
             SsaEnv* end_env = ssa_env_;
             SsaEnv* false_env = Split(ssa_env_);
             false_env->control = if_false;
@@ -816,7 +816,7 @@ class WasmFullDecoder : public WasmDecoder {
               DCHECK(fval.type != kAstEnd);
               DCHECK(cond.type != kAstEnd);
               TFNode* controls[2];
-              builder_->Branch(cond.node, &controls[0], &controls[1]);
+              builder_->BranchNoHint(cond.node, &controls[0], &controls[1]);
               TFNode* merge = builder_->Merge(2, controls);
               TFNode* vals[2] = {tval.node, fval.node};
               TFNode* phi = builder_->Phi(tval.type, 2, vals, merge);
@@ -843,7 +843,7 @@ class WasmFullDecoder : public WasmDecoder {
               SsaEnv* fenv = ssa_env_;
               SsaEnv* tenv = Split(fenv);
               fenv->SetNotMerged();
-              BUILD(Branch, cond.node, &tenv->control, &fenv->control);
+              BUILD(BranchNoHint, cond.node, &tenv->control, &fenv->control);
               ssa_env_ = tenv;
               BreakTo(operand.depth);
               ssa_env_ = fenv;