Revert "Roll clang n333938-3a6da112-1 : n340158-efb130fc-2."

This reverts commit 0aa05cca.

Reason for revert:
This broke arm64-builder-rel and some other builders, see bug.

Original change's description:
> Roll clang n333938-3a6da112-1 : n340158-efb130fc-2.
> 
> Ran `tools/clang/scripts/upload_revision.py efb130fc93059bdf02d3a83950ddabc5d119f9de`.
> 
> This increases the clang version from 10 to 11.
> 
> It also disables the use of vector instructions in zlib to work around
> new false positives in msan (see crbug.com/1045291).
> 
> Bug: 1030664
> Change-Id: I5417d3063f0d67a61cdf31141b05a51a56e84482
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2014904
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Commit-Queue: Hans Wennborg <hans@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#735080}

TBR=thakis@chromium.org,hans@chromium.org

Change-Id: I48754484c26ebf6b1f0b4a47c82fe3c74ee39837
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1030664,1045592
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2020785Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735124}

build/config/compiler/BUILD.gn

@@ -499,14 +499,15 @@ config("compiler") {
       "-instcombine-lower-dbg-declare=0",
     ]
 
-    # Before Clang 10, lax vector conversions were allowed by default.
-    # Chromium currently relies on this behavior.
-    # TODO(crbug.com/1042470): Fix the code and remove this flag.
-    if (is_win) {
-      cflags += [ "-Xclang", "-flax-vector-conversions=all" ]
-    } else if (!is_chromeos ||
-               default_toolchain != "//build/toolchain/cros:target") {
-      cflags += [ "-flax-vector-conversions=all" ]
+    if (llvm_force_head_revision) {
+      # Before Clang 10, lax vector conversions were allowed by default.
+      # Chromium currently relies on this behavior.
+      # TODO(crbug.com/1042470): Fix the code and remove this flag.
+      if (is_win) {
+        cflags += [ "/clang:-flax-vector-conversions=all" ]
+      } else if (cros_sdk_version == "") {
+        cflags += [ "-flax-vector-conversions=all" ]
+      }
     }
   }
 
@@ -1539,18 +1540,22 @@ config("default_warnings") {
 
           # TODO(https://crbug.com/1028110): Evaluate and possible enable.
           "-Wno-deprecated-copy",
-
-          # TODO(https://crbug.com/1031169): Clean up and enable.
-          "-Wno-misleading-indentation",
-
-          # TODO(https://crbug.com/1039697): Evaluate and possibly enable.
-          "-Wno-range-loop-analysis",
         ]
 
         cflags_c += [
           # TODO(https://crbug.com/995993): Clean up and enable.
           "-Wno-implicit-fallthrough",
         ]
+
+        if (llvm_force_head_revision) {
+          cflags += [
+            # TODO(https://crbug.com/1031169): Clean up and enable.
+            "-Wno-misleading-indentation",
+
+            # TODO(https://crbug.com/1039697): Evaluate and possibly enable.
+            "-Wno-range-loop-analysis",
+          ]
+        }
       }
     }
   }

build/toolchain/toolchain.gni

@@ -37,7 +37,12 @@ if (generate_linker_map) {
 declare_args() {
   if (is_clang) {
     # Clang compiler version. Clang files are placed at version-dependent paths.
-    clang_version = "11.0.0"
+    if (llvm_force_head_revision) {
+      clang_version = "11.0.0"
+    } else {
+      # TODO(crbug.com/1042192): Remove in the next Clang roll.
+      clang_version = "10.0.0"
+    }
   }
 }
 

third_party/blink/renderer/BUILD.gn

@@ -49,7 +49,7 @@ config("inside_blink") {
       "-Wno-implicit-int-conversion",
     ]
 
-    if (!is_chromeos || default_toolchain != "//build/toolchain/cros:target") {
+    if (llvm_force_head_revision) {
       cflags += [
         "-Wno-enum-enum-conversion",
         "-Wno-enum-float-conversion",

third_party/zlib/BUILD.gn

@@ -23,14 +23,17 @@ if (current_cpu == "arm" || current_cpu == "arm64") {
   }
 }
 
-# TODO(https://crbug.com/1045291): Re-enable once msan bug is fixed, should
-# be set to:
-#    (current_cpu == "x86" || current_cpu == "x64") && !is_ios
-use_x86_x64_optimizations = false
+use_x86_x64_optimizations =
+    (current_cpu == "x86" || current_cpu == "x64") && !is_ios
 
 config("zlib_adler32_simd_config") {
   if (use_x86_x64_optimizations) {
     defines = [ "ADLER32_SIMD_SSSE3" ]
+    if (is_win) {
+      defines += [ "X86_WINDOWS" ]
+    } else {
+      defines += [ "X86_NOT_WINDOWS" ]
+    }
   } else if (use_arm_neon_optimizations) {
     defines = [ "ADLER32_SIMD_NEON" ]
   }
@@ -268,16 +271,6 @@ component("zlib") {
     defines += [ "CPU_NO_SIMD" ]
   }
 
-  # For cpu_features.c
-  # TODO(https://crbug.com/1045291): Check use_x86_x64_optimizations instead.
-  if ((current_cpu == "x86" || current_cpu == "x64") && !is_ios) {
-    if (is_win) {
-      defines += [ "X86_WINDOWS" ]
-    } else {
-      defines += [ "X86_NOT_WINDOWS" ]
-    }
-  }
-
   if (is_ios) {
     # iOS@ARM is a special case where we always have NEON but don't check
     # for crypto extensions.

third_party/zlib/cpu_features.c

@@ -35,10 +35,12 @@ int ZLIB_INTERNAL x86_cpu_enable_simd = 0;
 #include <zircon/features.h>
 #include <zircon/syscalls.h>
 #include <zircon/types.h>
-#elif defined(_MSC_VER)
+#elif defined(ARMV8_OS_WINDOWS) || defined(X86_WINDOWS)
 #include <windows.h>
-#else
+#elif !defined(_MSC_VER)
 #include <pthread.h>
+#else
+#error cpu_features.c CPU feature detection in not defined for your platform
 #endif
 
 #if !defined(CPU_NO_SIMD) && !defined(ARM_OS_IOS)
@@ -49,17 +51,13 @@ static void _cpu_check_features(void);
 static pthread_once_t cpu_check_inited_once = PTHREAD_ONCE_INIT;
 void ZLIB_INTERNAL cpu_check_features(void)
 {
-#if !defined(CPU_NO_SIMD) && !defined(ARM_OS_IOS)
     pthread_once(&cpu_check_inited_once, _cpu_check_features);
-#endif
 }
-#elif defined(_MSC_VER)
+#elif defined(ARMV8_OS_WINDOWS) || defined(X86_WINDOWS)
 static INIT_ONCE cpu_check_inited_once = INIT_ONCE_STATIC_INIT;
 static BOOL CALLBACK _cpu_check_features_forwarder(PINIT_ONCE once, PVOID param, PVOID* context)
 {
-#if !defined(CPU_NO_SIMD) && !defined(ARM_OS_IOS)
     _cpu_check_features();
-#endif
     return TRUE;
 }
 void ZLIB_INTERNAL cpu_check_features(void)

tools/clang/scripts/build.py

@@ -338,6 +338,15 @@ def main():
                       default=sys.platform in ('linux2', 'darwin'))
   args = parser.parse_args()
 
+  # TODO(crbug.com/1042192): Remove in the next Clang roll.
+  if args.llvm_force_head_revision:
+    global RELEASE_VERSION
+    RELEASE_VERSION = '11.0.0'
+    old_lib_dir = os.path.join(LLVM_BUILD_DIR, 'lib', 'clang', '10.0.0')
+    if (os.path.isdir(old_lib_dir)):
+      print('Removing old lib dir: ' + old_lib_dir)
+      RmTree(old_lib_dir)
+
   if args.lto_lld and not args.bootstrap:
     print('--lto-lld requires --bootstrap')
     return 1
@@ -451,8 +460,6 @@ def main():
                      '-DCOMPILER_RT_USE_LIBCXX=NO',
                      # Don't run Go bindings tests; PGO makes them confused.
                      '-DLLVM_INCLUDE_GO_TESTS=OFF',
-                     # TODO(b/148147812) Goma client doesn't handle in-process cc1.
-                     '-DCLANG_SPAWN_CC1=ON',
                      ]
 
   if args.gcc_toolchain:

tools/clang/scripts/update.py

@@ -39,13 +39,14 @@ import zipfile
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://chromium.googlesource.com/chromium/src/+/master/docs/updating_clang.md
 # Reverting problematic clang rolls is safe, though.
-CLANG_REVISION = 'efb130fc93059bdf02d3a83950ddabc5d119f9de'
-CLANG_SVN_REVISION = 'n340158'
-CLANG_SUB_REVISION = 2
+CLANG_REVISION = 'c2443155a0fb245c8f17f2c1c72b6ea391e86e81'
+CLANG_SVN_REVISION = 'n332890'
+CLANG_SUB_REVISION = 1
 
 PACKAGE_VERSION = '%s-%s-%s' % (CLANG_SVN_REVISION, CLANG_REVISION[:8],
                                 CLANG_SUB_REVISION)
-RELEASE_VERSION = '11.0.0'
+# TODO(crbug.com/985289): Bump to 11.0.0 in the next Clang roll.
+RELEASE_VERSION = '10.0.0'
 
 
 CDS_URL = os.environ.get('CDS_CLANG_BUCKET_OVERRIDE',
@@ -340,6 +341,11 @@ def main():
                       help='Verify that clang has the passed-in version.')
   args = parser.parse_args()
 
+  # TODO(crbug.com/1042192): Remove in the next Clang roll.
+  if args.llvm_force_head_revision:
+    global RELEASE_VERSION
+    RELEASE_VERSION = '11.0.0'
+
   if args.force_local_build:
     print(('update.py --force-local-build is no longer used to build clang; '
            'use build.py instead.'))