Drop lying to the compiler in the fletcher4 code

This is probably the uncontroversial part of #13631, which fixes
a real problem people are having.

There's still things to improve in our code after this is merged,
but it should stop the breakage that people have reported, where
we lie about a type always being aligned and then pass in stack
objects with no alignment requirement and hope for the best.

Of course, our SIMD code was written with unaligned accesses, so it
doesn't care if we drop this...but some auto-vectorized code that
gcc emits sure does, since we told it it can assume they're aligned.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Tino Reichardt <[email protected]>
Reviewed-by: Richard Yao <[email protected]>
Signed-off-by: Rich Ercolani <[email protected]>
Closes #14649 

1 files changed, 4 insertions, 20 deletions

diff --git a/include/zfs_fletcher.h b/include/zfs_fletcher.h
index e913a0bd7..ca1a09292 100644
--- a/include/zfs_fletcher.h
+++ b/include/zfs_fletcher.h
@@ -76,19 +76,19 @@ typedef struct zfs_fletcher_superscalar {
 } zfs_fletcher_superscalar_t;
 
 typedef struct zfs_fletcher_sse {
-	uint64_t v[2] __attribute__((aligned(16)));
+	uint64_t v[2];
 } zfs_fletcher_sse_t;
 
 typedef struct zfs_fletcher_avx {
-	uint64_t v[4] __attribute__((aligned(32)));
+	uint64_t v[4];
 } zfs_fletcher_avx_t;
 
 typedef struct zfs_fletcher_avx512 {
-	uint64_t v[8] __attribute__((aligned(64)));
+	uint64_t v[8];
 } zfs_fletcher_avx512_t;
 
 typedef struct zfs_fletcher_aarch64_neon {
-	uint64_t v[2] __attribute__((aligned(16)));
+	uint64_t v[2];
 } zfs_fletcher_aarch64_neon_t;
 
 
@@ -161,20 +161,4 @@ _ZFS_FLETCHER_H const fletcher_4_ops_t fletcher_4_aarch64_neon_ops;
 }
 #endif
 
-#if	defined(ZFS_UBSAN_ENABLED)
-#if	defined(__has_attribute)
-#if	__has_attribute(no_sanitize_undefined)
-#define	ZFS_NO_SANITIZE_UNDEFINED __attribute__((no_sanitize_undefined))
-#elif	__has_attribute(no_sanitize)
-#define	ZFS_NO_SANITIZE_UNDEFINED __attribute__((no_sanitize("undefined")))
-#else
-#error	"Compiler has to support attribute "
-	"`no_sanitize_undefined` or `no_sanitize(\"undefined\")`"
-	"when compiling with UBSan enabled"
-#endif	/* __has_attribute(no_sanitize_undefined) */
-#endif	/* defined(__has_attribute) */
-#else
-#define	ZFS_NO_SANITIZE_UNDEFINED
-#endif	/* defined(ZFS_UBSAN_ENABLED) */
-
 #endif	/* _ZFS_FLETCHER_H */