Move fp16 dependency to Bazel & patch v8

Author: garrettgu10

WORKSPACE

@@ -190,6 +190,13 @@ git_repository(
     remote = "https://chromium.googlesource.com/chromium/src/third_party/abseil-cpp.git",
 )
 
+git_repository(
+    name = "fp16",
+    commit = "0a92994d729ff76a58f692d3028ca1b64b145d91",
+    build_file_content = "exports_files(glob([\"**\"]))",
+    remote = "https://chromium.googlesource.com/external/github.com/Maratyszcza/FP16.git"
+)
+
 # Bindings for abseil libraries used by V8
 [
     bind(
@@ -449,7 +456,8 @@ http_archive(
         "//:patches/v8/0012-Always-enable-continuation-preserved-data-in-the-bui.patch",
         "//:patches/v8/0013-increase-visibility-of-virtual-method.patch",
         "//:patches/v8/0014-Add-ValueSerializer-SetTreatFunctionsAsHostObjects.patch",
-        "//:patches/v8/0015-Set-torque-generator-path-to-external-v8.-This-allow.patch"
+        "//:patches/v8/0015-Set-torque-generator-path-to-external-v8.-This-allow.patch",
+        "//:patches/v8/0016-Modify-where-to-look-for-fp16-dependency.-This-depen.patch"
     ],
     integrity = "sha256-C6bsXXbKgeCxmG1VNO/LScaPq0HVlmofpVHJ5kswoLg=",
     strip_prefix = "v8-12.4.254.11",

patches/v8/0015-Set-torque-generator-path-to-external-v8.-This-allow.patch

@@ -17,6 +17,6 @@ index e55defede9fed3eea9348bd7bd50d98f688a2a7b..faeef2b2ed71b4784050451a61a16feb
  def _torque_files_impl(ctx):
 -    v8root = "."
 +    v8root = "external/v8"
-
+ 
      # Arguments
      args = []

patches/v8/0016-Modify-where-to-look-for-fp16-dependency.-This-depen.patch

@@ -0,0 +1,48 @@
+From b8c3575ff696eac20bd8d94f49407b52642087c1 Mon Sep 17 00:00:00 2001
+From: Garrett Gu <[email protected]>
+Date: Mon, 22 Apr 2024 10:10:21 -0500
+Subject: Modify where to look for fp16 dependency. This dependency is normally
+ downloaded by gn but we need to fetch it in Bazel. We do so in the workerd
+ repo in the WORKSPACE file.
+
+---
+ BUILD.bazel | 26 ++++++++++++++++----------
+ 1 file changed, 16 insertions(+), 10 deletions(-)
+
+diff --git a/BUILD.bazel b/BUILD.bazel
+index f3e7958b39e5b7e42b06fad83a0bf6f7352ffd3c..e1fed34c700e88cb7a54450d0f2c7cb34c6c921f 100644
+--- a/BUILD.bazel
++++ b/BUILD.bazel
+@@ -3689,16 +3689,22 @@ filegroup(
+     }),
+ )
+ 
+-v8_library(
+-  name = "lib_fp16",
+-  srcs = ["third_party/fp16/src/include/fp16.h"],
+-  hdrs = [
+-    "third_party/fp16/src/include/fp16/fp16.h",
+-    "third_party/fp16/src/include/fp16/bitcasts.h",
+-  ],
+-  includes = [
+-    "third_party/fp16/src/include",
+-  ],
++cc_library(
++    name = "lib_fp16",
++    hdrs = [
++        "@fp16//:include/fp16.h",
++    ],
++    include_prefix = "third_party/fp16/src",
++    deps = [":lib_fp16_includes"],
++)
++
++cc_library(
++    name = "lib_fp16_includes",
++    hdrs = [
++        "@fp16//:include/fp16/bitcasts.h",
++        "@fp16//:include/fp16/fp16.h",
++    ],
++    strip_include_prefix = "include",
+ )
+ 
+ filegroup(