Revert "[wasm-simd] Fix scalar lowering of kParameter"

This reverts commit e8832647b6.

Reason for revert: Causes flaky fails on the tree, reverting as this test should be deterministic pass/fail.

https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8889903130443940000/+/steps/Check_-_nosse3__flakes_/0/logs/simd-call/0

Original change's description:
> [wasm-simd] Fix scalar lowering of kParameter
> 
> Lowers the call descriptor of a wasm function if it contains simd.
> 
> Also fixes a couple of issues with the lowering of kParameter:
> - the old_index == new_index check is incorrect, it would only work if
> the s128 parameter is the first parameter
> - the old_index was also not adjusted to account for Parameter[0] being
> the wasm instance object
> - new_index needs to be adjusted to account for the instance object too
> 
> These fixes make it more similar to the lowering of kParameter in
> int64-lowering.c.
> 
> Also add a new mjsunit test to exercise this logic.
> 
> Bug: v8:10154
> Change-Id: Ia767a464c26a6a78fd931eab9e6897890a0904e8
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2020521
> Commit-Queue: Zhi An Ng <zhin@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66032}

TBR=gdeepti@chromium.org,ahaas@chromium.org,zhin@chromium.org

Change-Id: I69589e2331c857c0f197ac53b8fb8a241376c632
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10154
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2028830
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66034}

src/compiler/simd-scalar-lowering.cc

@@ -909,36 +909,29 @@ void SimdScalarLowering::LowerNode(Node* node) {
     }
     case IrOpcode::kParameter: {
       DCHECK_EQ(1, node->InputCount());
-      int param_count = static_cast<int>(signature()->parameter_count());
       // Only exchange the node if the parameter count actually changed. We do
-      // not even have to do the default lowering because the start node,
+      // not even have to do the default lowering because the the start node,
       // the only input of a parameter node, only changes if the parameter count
       // changes.
-      if (GetParameterCountAfterLowering() != param_count) {
+      if (GetParameterCountAfterLowering() !=
+          static_cast<int>(signature()->parameter_count())) {
         int old_index = ParameterIndexOf(node->op());
-        // Parameter index 0 is the instance parameter, we will use old_index to
-        // index into the function signature, so we need to decrease it by 1.
-        --old_index;
         int new_index =
             GetParameterIndexAfterLoweringSimd128(signature(), old_index);
-        // Similarly, the index into function signature needs to account for the
+        if (old_index == new_index) {
-        // instance parameter, so increase it by 1.
+          NodeProperties::ChangeOp(node, common()->Parameter(new_index));
-        ++new_index;
-        NodeProperties::ChangeOp(node, common()->Parameter(new_index));
 
-        if (old_index < 0) {
-          break;
-        }
-
-        DCHECK(old_index < param_count);
-
-        if (signature()->GetParam(old_index) ==
-            MachineRepresentation::kSimd128) {
           Node* new_node[kNumLanes32];
+          for (int i = 0; i < kNumLanes32; ++i) {
+            new_node[i] = nullptr;
+          }
           new_node[0] = node;
-          for (int i = 1; i < kNumLanes32; ++i) {
+          if (signature()->GetParam(old_index) ==
-            new_node[i] = graph()->NewNode(common()->Parameter(new_index + i),
+              MachineRepresentation::kSimd128) {
-                                           graph()->start());
+            for (int i = 1; i < kNumLanes32; ++i) {
+              new_node[i] = graph()->NewNode(common()->Parameter(new_index + i),
+                                             graph()->start());
+            }
           }
           ReplaceNode(node, new_node, kNumLanes32);
         }

src/compiler/wasm-compiler.cc

@@ -6932,11 +6932,6 @@ wasm::WasmCompilationResult ExecuteTurbofanWasmCompilation(
     call_descriptor = GetI32WasmCallDescriptor(&zone, call_descriptor);
   }
 
-  if (ContainsSimd(func_body.sig) &&
-      (!CpuFeatures::SupportsWasmSimd128() || env->lower_simd)) {
-    call_descriptor = GetI32WasmCallDescriptorForSimd(&zone, call_descriptor);
-  }
-
   Pipeline::GenerateCodeForWasmFunction(
       &info, wasm_engine, mcgraph, call_descriptor, source_positions,
       node_origins, func_body, env->module, func_index);

test/mjsunit/wasm/simd-call.js

@@ -1,66 +0,0 @@
-// Copyright 2020 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.
-
-// Flags: --experimental-wasm-simd
-
-load('test/mjsunit/wasm/wasm-module-builder.js');
-
-// Tests function calls containing s128 parameters. It also checks that
-// lowering of simd calls are correct, so we create 2 functions with s128
-// arguments: function 2 has a single s128 parameter, function 3 has a i32 then
-// s128, to ensure that the arguments in different indices are correctly lowered.
-(function TestSimd128Params() {
-  const builder = new WasmModuleBuilder();
-  builder.addImportedMemory('m', 'imported_mem', 1, 2);
-
-  builder
-    .addFunction("main", makeSig([], []))
-    .addBodyWithEnd([
-      kExprI32Const, 0,
-      kSimdPrefix, kExprS128LoadMem, 0, 0,
-      kExprCallFunction, 0x01,
-      kExprEnd,
-    ]);
-
-  // Writes s128 argument to memory starting byte 16.
-  builder
-    .addFunction("function2", makeSig([kWasmS128], []))
-    .addBodyWithEnd([
-      kExprI32Const, 16,
-      kExprLocalGet, 0,
-      kSimdPrefix, kExprS128StoreMem, 0, 0,
-      kExprI32Const, 9, // This constant doesn't matter.
-      kExprLocalGet, 0,
-      kExprCallFunction, 0x02,
-      kExprEnd,
-    ]);
-
-  // Writes s128 argument to memory starting byte 32.
-  builder
-    .addFunction("function3", makeSig([kWasmI32, kWasmS128], []))
-    .addBodyWithEnd([
-      kExprI32Const, 32,
-      kExprLocalGet, 1,
-      kSimdPrefix, kExprS128StoreMem, 0, 0,
-      kExprEnd,
-    ]);
-
-  builder.addExport('main', 0);
-  var memory = new WebAssembly.Memory({initial:1, maximum:2});
-  const instance = builder.instantiate({m: {imported_mem: memory}});
-
-  const arr = new Uint8Array(memory.buffer);
-  // Fill the initial memory with some values, this is read by main and passed
-  // as arguments to function2, and then to function3.
-  for (let i = 0; i < 16; i++) {
-    arr[i] = i * 2;
-  }
-
-  instance.exports.main();
-
-  for (let i = 0; i < 16; i++) {
-    assertEquals(arr[i], arr[i+16]);
-    assertEquals(arr[i], arr[i+32]);
-  }
-})();