[csa] tnodify Uint8 clamp functions

This tnodifies CodeStubAssembler::Float64ToUint8Clamped and
Int32ToUint8Clamped.

Bug: v8:6949
Change-Id: I79c8cd45dc4c8333f268cf0a62234d75369f89b6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1813024
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63922}

src/codegen/code-stub-assembler.cc

@@ -7,6 +7,7 @@
 #include "include/v8-internal.h"
 #include "src/base/macros.h"
 #include "src/codegen/code-factory.h"
+#include "src/codegen/tnode.h"
 #include "src/common/globals.h"
 #include "src/execution/frames-inl.h"
 #include "src/execution/frames.h"
@@ -10706,33 +10707,35 @@ void CodeStubAssembler::StoreElement(Node* elements, ElementsKind kind,
   }
 }
 
-Node* CodeStubAssembler::Int32ToUint8Clamped(Node* int32_value) {
+TNode<Uint8T> CodeStubAssembler::Int32ToUint8Clamped(
+    TNode<Int32T> int32_value) {
   Label done(this);
   TNode<Int32T> int32_zero = Int32Constant(0);
   TNode<Int32T> int32_255 = Int32Constant(255);
-  VARIABLE(var_value, MachineRepresentation::kWord32, int32_value);
+  TVARIABLE(Word32T, var_value, int32_value);
   GotoIf(Uint32LessThanOrEqual(int32_value, int32_255), &done);
-  var_value.Bind(int32_zero);
+  var_value = int32_zero;
   GotoIf(Int32LessThan(int32_value, int32_zero), &done);
-  var_value.Bind(int32_255);
+  var_value = int32_255;
   Goto(&done);
   BIND(&done);
-  return var_value.value();
+  return UncheckedCast<Uint8T>(var_value.value());
 }
 
-Node* CodeStubAssembler::Float64ToUint8Clamped(Node* float64_value) {
+TNode<Uint8T> CodeStubAssembler::Float64ToUint8Clamped(
+    TNode<Float64T> float64_value) {
   Label done(this);
-  VARIABLE(var_value, MachineRepresentation::kWord32, Int32Constant(0));
+  TVARIABLE(Word32T, var_value, Int32Constant(0));
   GotoIf(Float64LessThanOrEqual(float64_value, Float64Constant(0.0)), &done);
-  var_value.Bind(Int32Constant(255));
+  var_value = Int32Constant(255);
   GotoIf(Float64LessThanOrEqual(Float64Constant(255.0), float64_value), &done);
   {
     TNode<Float64T> rounded_value = Float64RoundToEven(float64_value);
-    var_value.Bind(TruncateFloat64ToWord32(rounded_value));
+    var_value = TruncateFloat64ToWord32(rounded_value);
     Goto(&done);
   }
   BIND(&done);
-  return var_value.value();
+  return UncheckedCast<Uint8T>(var_value.value());
 }
 
 Node* CodeStubAssembler::PrepareValueForWriteToTypedArray(

src/codegen/code-stub-assembler.h

@@ -3287,8 +3287,8 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
   TNode<Context> LoadScriptContext(TNode<Context> context,
                                    TNode<IntPtrT> context_index);
 
-  Node* Int32ToUint8Clamped(Node* int32_value);
-  Node* Float64ToUint8Clamped(Node* float64_value);
+  TNode<Uint8T> Int32ToUint8Clamped(TNode<Int32T> int32_value);
+  TNode<Uint8T> Float64ToUint8Clamped(TNode<Float64T> float64_value);
 
   Node* PrepareValueForWriteToTypedArray(TNode<Object> input,
                                          ElementsKind elements_kind,