88 lines
2.9 KiB
Diff
88 lines
2.9 KiB
Diff
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From f2076c6a4c9c14538d71a3ef9c9e4fd40ee6ee00 Mon Sep 17 00:00:00 2001
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From: Stephan Hartmann <stha09@googlemail.com>
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Date: Sun, 31 May 2020 11:46:05 +0000
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Subject: [PATCH] GCC: fix __has_builtin defines for non-clang compilers
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Defining __has_builtin to 0 for non-clang compilers in base headers can
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lead to wrong detection of features. For example in base/location.h
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checking for __has_builtin macros succeeds for non-clang compilers,
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because base/check_op.h defines __has_builtin to 0 and is included
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before base/location.h. Instead of defining __has_builtin to 0 for
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non-clang compilers, define an independent preprocessor symbol that
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reflects support for requested feature. Undefine the symbol to avoid
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collision.
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While we're at it fix base/memory/aligned_memory.h too.
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Bug: 819294
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Change-Id: Iac40dc44e7356b600e7d06aa4ccd1294bb09ebce
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---
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diff --git a/base/check_op.h b/base/check_op.h
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index 04b0c6f..28f4263a 100644
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--- a/base/check_op.h
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+++ b/base/check_op.h
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@@ -48,8 +48,10 @@
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void (*stream_func)(std::ostream&,
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const void*));
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-#ifndef __has_builtin
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-#define __has_builtin(x) 0 // Compatibility with non-clang compilers.
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+#ifdef __has_builtin
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+#define SUPPORTS_BUILTIN_ADDRESSOF (__has_builtin(__builtin_addressof))
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+#else
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+#define SUPPORTS_BUILTIN_ADDRESSOF 0
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#endif
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template <typename T>
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@@ -65,7 +67,7 @@
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// operator& might be overloaded, so do the std::addressof dance.
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// __builtin_addressof is preferred since it also handles Obj-C ARC pointers.
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// Some casting is still needed, because T might be volatile.
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-#if __has_builtin(__builtin_addressof)
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+#if SUPPORTS_BUILTIN_ADDRESSOF
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const void* vp = const_cast<const void*>(
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reinterpret_cast<const volatile void*>(__builtin_addressof(v)));
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#else
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@@ -75,6 +77,8 @@
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return StreamValToStr(vp, f);
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}
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+#undef SUPPORTS_BUILTIN_ADDRESSOF
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+
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// Overload for types that have no operator<< but do have .ToString() defined.
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template <typename T>
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inline typename std::enable_if<
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diff --git a/base/memory/aligned_memory.h b/base/memory/aligned_memory.h
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index d1cba0c..a0d9f13 100644
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--- a/base/memory/aligned_memory.h
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+++ b/base/memory/aligned_memory.h
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@@ -57,13 +57,15 @@
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}
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};
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-#ifndef __has_builtin
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-#define __has_builtin(x) 0 // Compatibility with non-clang compilers.
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+#ifdef __has_builtin
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+#define SUPPORTS_BUILTIN_IS_ALIGNED (__has_builtin(__builtin_is_aligned))
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+#else
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+#define SUPPORTS_BUILTIN_IS_ALIGNED 0
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#endif
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inline bool IsAligned(uintptr_t val, size_t alignment) {
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// If the compiler supports builtin alignment checks prefer them.
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-#if __has_builtin(__builtin_is_aligned)
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+#if SUPPORTS_BUILTIN_IS_ALIGNED
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return __builtin_is_aligned(val, alignment);
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#else
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DCHECK(!((alignment - 1) & alignment))
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@@ -72,6 +74,8 @@
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#endif
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}
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+#undef SUPPORTS_BUILTIN_IS_ALIGNED
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+
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inline bool IsAligned(void* val, size_t alignment) {
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return IsAligned(reinterpret_cast<uintptr_t>(val), alignment);
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}
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