[PATCH] Use unaligned memory accesses unconditionally

[Fangrui Song]

From: Fangrui Song <i@maskray.me>

Currently ALIGNMENT_WORKAROUND is only defined for __ia64__ and __arm__.
However, -fsanitize=alignment (part of UndefinedBehaviorSanitizer) will
give errors for other architectures like x86. Modern compilers are able
to optimize the memory access, so let's just use unaligned memory
accesses unconditionally.
---
 Makefile |  1 -
 config.h |  5 -----
 types.h  | 12 ------------
 3 files changed, 18 deletions(-)

diff --git a/Makefile b/Makefile
index 7aa729d..3e83805 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,6 @@ CFLAGS += -W -Wall -Wshadow -Wstrict-prototypes 
-Wpointer-arith -Wcast-qual \
 CFLAGS += -D_FILE_OFFSET_BITS=64
 
 #CFLAGS += -DBIGENDIAN
-#CFLAGS += -DALIGNMENT_WORKAROUND
 
 # Pass linker flags here (can be set from environment too)
 LDFLAGS ?=
diff --git a/config.h b/config.h
index 0a1af7d..416d4a6 100644
--- a/config.h
+++ b/config.h
@@ -21,11 +21,6 @@
 #define USE_MMAP
 #endif
 
-/* Use memory alignment workaround or not */
-#if defined(__ia64__) || defined(__arm__)
-#define ALIGNMENT_WORKAROUND
-#endif
-
 /* Avoid unaligned memcpy on /dev/mem */
 #ifdef __aarch64__
 #define USE_SLOW_MEMCPY
diff --git a/types.h b/types.h
index 51c32d7..d445cd6 100644
--- a/types.h
+++ b/types.h
@@ -12,10 +12,6 @@ typedef unsigned int u32;
  * You may use the following defines to adjust the type definitions
  * depending on the architecture:
  * - Define BIGENDIAN on big-endian systems.
- * - Define ALIGNMENT_WORKAROUND if your system doesn't support
- *   non-aligned memory access. In this case, we use a slower, but safer,
- *   memory access method. This should be done automatically in config.h
- *   for architectures which need it.
  */
 
 #ifdef BIGENDIAN
@@ -30,7 +26,6 @@ typedef struct {
 } u64;
 #endif
 
-#if defined(ALIGNMENT_WORKAROUND) || defined(BIGENDIAN)
 static inline u64 U64(u32 low, u32 high)
 {
        u64 self;
@@ -40,20 +35,13 @@ static inline u64 U64(u32 low, u32 high)
 
        return self;
 }
-#endif
 
 /*
  * Per SMBIOS v2.8.0 and later, all structures assume a little-endian
  * ordering convention.
  */
-#if defined(ALIGNMENT_WORKAROUND) || defined(BIGENDIAN)
 #define WORD(x) (u16)((x)[0] + ((x)[1] << 8))
 #define DWORD(x) (u32)((x)[0] + ((x)[1] << 8) + ((x)[2] << 16) + ((x)[3] << 
24))
 #define QWORD(x) (U64(DWORD(x), DWORD(x + 4)))
-#else /* ALIGNMENT_WORKAROUND || BIGENDIAN */
-#define WORD(x) (u16)(*(const u16 *)(x))
-#define DWORD(x) (u32)(*(const u32 *)(x))
-#define QWORD(x) (*(const u64 *)(x))
-#endif /* ALIGNMENT_WORKAROUND || BIGENDIAN */
 
 #endif
-- 
2.41.0.585.gd2178a4bd4-goog