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-rw-r--r--include/linux/compiler-gcc.h87
1 files changed, 87 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
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+++ b/include/linux/compiler-gcc.h
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+#ifndef __LINUX_COMPILER_H
+#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
+#endif
+
+/*
+ * Common definitions for all gcc versions go here.
+ */
+
+
+/* Optimization barrier */
+/* The "volatile" is due to gcc bugs */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+/*
+ * This macro obfuscates arithmetic on a variable address so that gcc
+ * shouldn't recognize the original var, and make assumptions about it.
+ *
+ * This is needed because the C standard makes it undefined to do
+ * pointer arithmetic on "objects" outside their boundaries and the
+ * gcc optimizers assume this is the case. In particular they
+ * assume such arithmetic does not wrap.
+ *
+ * A miscompilation has been observed because of this on PPC.
+ * To work around it we hide the relationship of the pointer and the object
+ * using this macro.
+ *
+ * Versions of the ppc64 compiler before 4.1 had a bug where use of
+ * RELOC_HIDE could trash r30. The bug can be worked around by changing
+ * the inline assembly constraint from =g to =r, in this particular
+ * case either is valid.
+ */
+#define RELOC_HIDE(ptr, off) \
+ ({ unsigned long __ptr; \
+ __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
+ (typeof(ptr)) (__ptr + (off)); })
+
+/* &a[0] degrades to a pointer: a different type from an array */
+#define __must_be_array(a) \
+ BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0])))
+
+/*
+ * Force always-inline if the user requests it so via the .config,
+ * or if gcc is too old:
+ */
+#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
+ !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
+# define inline inline __attribute__((always_inline))
+# define __inline__ __inline__ __attribute__((always_inline))
+# define __inline __inline __attribute__((always_inline))
+#endif
+
+#define __deprecated __attribute__((deprecated))
+#define __packed __attribute__((packed))
+#define __weak __attribute__((weak))
+
+/*
+ * it doesn't make sense on ARM (currently the only user of __naked) to trace
+ * naked functions because then mcount is called without stack and frame pointer
+ * being set up and there is no chance to restore the lr register to the value
+ * before mcount was called.
+ */
+#define __naked __attribute__((naked)) notrace
+
+#define __noreturn __attribute__((noreturn))
+
+/*
+ * From the GCC manual:
+ *
+ * Many functions have no effects except the return value and their
+ * return value depends only on the parameters and/or global
+ * variables. Such a function can be subject to common subexpression
+ * elimination and loop optimization just as an arithmetic operator
+ * would be.
+ * [...]
+ */
+#define __pure __attribute__((pure))
+#define __aligned(x) __attribute__((aligned(x)))
+#define __printf(a,b) __attribute__((format(printf,a,b)))
+#define noinline __attribute__((noinline))
+#define __attribute_const__ __attribute__((__const__))
+#define __maybe_unused __attribute__((unused))
+#define __always_unused __attribute__((unused))
+
+#define __gcc_header(x) #x
+#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
+#define gcc_header(x) _gcc_header(x)
+#include gcc_header(__GNUC__)