[wasm] Chain diamond patterns to current control in wasm compiler

Diamond patterns need to be chained to the current control node. This
was not done consistently in wasm code, particularly the parts
implementing asm-js specific instructions.

Additionally, the graph structure for BuildI32AsmjsDivS is improved.

Change-Id: I4a17e431b5795c197bf56dd034ff5e7d95dd6db0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2578982Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71677}

src/compiler/wasm-compiler.cc

@@ -2532,7 +2532,7 @@ Node* WasmGraphBuilder::BuildI32AsmjsDivS(Node* left, Node* right) {
   // asm.js semantics return 0 on divide or mod by zero.
   if (m->Int32DivIsSafe()) {
     // The hardware instruction does the right thing (e.g. arm).
-    return graph()->NewNode(m->Int32Div(), left, right, graph()->start());
+    return graph()->NewNode(m->Int32Div(), left, right, control());
   }
 
   // Check denominator for zero.
@@ -2540,20 +2540,22 @@ Node* WasmGraphBuilder::BuildI32AsmjsDivS(Node* left, Node* right) {
       graph(), mcgraph()->common(),
       graph()->NewNode(m->Word32Equal(), right, mcgraph()->Int32Constant(0)),
       BranchHint::kFalse);
+  z.Chain(control());
 
-  // Check numerator for -1. (avoid minint / -1 case).
+  // Check denominator for -1. (avoid minint / -1 case).
   Diamond n(
       graph(), mcgraph()->common(),
       graph()->NewNode(m->Word32Equal(), right, mcgraph()->Int32Constant(-1)),
       BranchHint::kFalse);
+  n.Chain(z.if_false);
+
+  Node* div = graph()->NewNode(m->Int32Div(), left, right, n.if_false);
 
-  Node* div = graph()->NewNode(m->Int32Div(), left, right, z.if_false);
   Node* neg =
       graph()->NewNode(m->Int32Sub(), mcgraph()->Int32Constant(0), left);
 
-  return n.Phi(
-      MachineRepresentation::kWord32, neg,
-      z.Phi(MachineRepresentation::kWord32, mcgraph()->Int32Constant(0), div));
+  return z.Phi(MachineRepresentation::kWord32, mcgraph()->Int32Constant(0),
+               n.Phi(MachineRepresentation::kWord32, neg, div));
 }
 
 Node* WasmGraphBuilder::BuildI32AsmjsRemS(Node* left, Node* right) {
@@ -2596,7 +2598,7 @@ Node* WasmGraphBuilder::BuildI32AsmjsRemS(Node* left, Node* right) {
 
   Node* check0 = graph()->NewNode(m->Int32LessThan(), zero, right);
   Node* branch0 =
-      graph()->NewNode(c->Branch(BranchHint::kTrue), check0, graph()->start());
+      graph()->NewNode(c->Branch(BranchHint::kTrue), check0, control());
 
   Node* if_true0 = graph()->NewNode(c->IfTrue(), branch0);
   Node* true0;
@@ -2659,7 +2661,7 @@ Node* WasmGraphBuilder::BuildI32AsmjsDivU(Node* left, Node* right) {
   // asm.js semantics return 0 on divide or mod by zero.
   if (m->Uint32DivIsSafe()) {
     // The hardware instruction does the right thing (e.g. arm).
-    return graph()->NewNode(m->Uint32Div(), left, right, graph()->start());
+    return graph()->NewNode(m->Uint32Div(), left, right, control());
   }
 
   // Explicit check for x % 0.
@@ -2667,6 +2669,7 @@ Node* WasmGraphBuilder::BuildI32AsmjsDivU(Node* left, Node* right) {
       graph(), mcgraph()->common(),
       graph()->NewNode(m->Word32Equal(), right, mcgraph()->Int32Constant(0)),
       BranchHint::kFalse);
+  z.Chain(control());
 
   return z.Phi(MachineRepresentation::kWord32, mcgraph()->Int32Constant(0),
                graph()->NewNode(mcgraph()->machine()->Uint32Div(), left, right,
@@ -2681,6 +2684,7 @@ Node* WasmGraphBuilder::BuildI32AsmjsRemU(Node* left, Node* right) {
       graph(), mcgraph()->common(),
       graph()->NewNode(m->Word32Equal(), right, mcgraph()->Int32Constant(0)),
       BranchHint::kFalse);
+  z.Chain(control());
 
   Node* rem = graph()->NewNode(mcgraph()->machine()->Uint32Mod(), left, right,
                                z.if_false);