From f316375a9531241c73988c9b56aa05f4ac8c5261 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <acozzette@google.com>
Date: Tue, 28 Mar 2017 09:21:13 -0700
Subject: [PATCH] Added a workaround to allow building for NaCl
arm-nacl-clang seems to produce a mysterious compiler error when it
encounters __builtin_clzll, so when we are building for NaCl, let's
avoid that in favor of the portable implementation of
Log2FloorNonZero64.
---
src/google/protobuf/stubs/port.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/google/protobuf/stubs/port.h b/src/google/protobuf/stubs/port.h
index 6f0633c4b0..6ec5e001fc 100644
--- a/src/google/protobuf/stubs/port.h
+++ b/src/google/protobuf/stubs/port.h
@@ -44,6 +44,8 @@
#include <stdint.h>
#endif
+#include <google/protobuf/stubs/platform_macros.h>
+
#undef PROTOBUF_LITTLE_ENDIAN
#ifdef _WIN32
// Assuming windows is always little-endian.
@@ -359,7 +361,12 @@ class Bits {
}
static uint32 Log2FloorNonZero64(uint64 n) {
-#if defined(__GNUC__)
+ // arm-nacl-clang runs into an instruction-selection failure when it
+ // encounters __builtin_clzll:
+ // https://bugs.chromium.org/p/nativeclient/issues/detail?id=4395
+ // To work around this, when we build for NaCl we use the portable
+ // implementation instead.
+#if defined(__GNUC__) && !defined(GOOGLE_PROTOBUF_OS_NACL)
return 63 ^ __builtin_clzll(n);
#else
return Log2FloorNonZero64_Portable(n);