Fix Clang 15 compilation errors

- Clang 15 doesn't support `-fno-ipa-sra` anymore. Do a separate
  check for `-fno-ipa-sra` support by $KERNEL_CC.

- Don't enable `-mgeneral-regs-only` for certain module files.
  Fix #13260

- Scope `GCC diagnostic ignored` statements to GCC only. Clang
  doesn't need them to compile the code.

Porting notes:
- Moved the stanzas removing -mgeneral-regs-only to Makefile.in
  since they wouldn't readily work in Kbuild.in and that did.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #13260
Closes #14150

Closes #14624
Ported-by: Rich Ercolani <rincebrain@gmail.com
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>

config/always-compiler-options.m4

@@ -221,3 +221,34 @@ AC_DEFUN([ZFS_AC_CONFIG_ALWAYS_CC_NO_IPA_SRA], [
 	CFLAGS="$saved_flags"
 	AC_SUBST([NO_IPA_SRA])
 ])
+
+dnl #
+dnl # Check if kernel cc supports -fno-ipa-sra option.
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_ALWAYS_KERNEL_CC_NO_IPA_SRA], [
+	AC_MSG_CHECKING([whether $KERNEL_CC supports -fno-ipa-sra])
+
+	saved_cc="$CC"
+	saved_flags="$CFLAGS"
+	CC="gcc"
+	CFLAGS="$CFLAGS -Werror -fno-ipa-sra"
+
+	AS_IF([ test -n "$KERNEL_CC" ], [
+		CC="$KERNEL_CC"
+	])
+	AS_IF([ test -n "$KERNEL_LLVM" ], [
+		CC="clang"
+	])
+
+	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [])], [
+		KERNEL_NO_IPA_SRA=-fno-ipa-sra
+		AC_MSG_RESULT([yes])
+	], [
+		KERNEL_NO_IPA_SRA=
+		AC_MSG_RESULT([no])
+	])
+
+	CC="$saved_cc"
+	CFLAGS="$saved_flags"
+	AC_SUBST([KERNEL_NO_IPA_SRA])
+])

config/zfs-build.m4

@@ -81,7 +81,7 @@ AC_DEFUN([ZFS_AC_DEBUG], [
 AC_DEFUN([ZFS_AC_DEBUGINFO_ENABLE], [
 	DEBUG_CFLAGS="$DEBUG_CFLAGS -g -fno-inline $NO_IPA_SRA"
 
-	KERNEL_DEBUG_CFLAGS="$KERNEL_DEBUG_CFLAGS -fno-inline $NO_IPA_SRA"
+	KERNEL_DEBUG_CFLAGS="$KERNEL_DEBUG_CFLAGS -fno-inline $KERNEL_NO_IPA_SRA"
 	KERNEL_MAKE="$KERNEL_MAKE CONFIG_DEBUG_INFO=y"
 
 	DEBUGINFO_ZFS="_with_debuginfo"
@@ -217,6 +217,7 @@ AC_DEFUN([ZFS_AC_CONFIG_ALWAYS], [
 	ZFS_AC_CONFIG_ALWAYS_CC_NO_FORMAT_ZERO_LENGTH
 	ZFS_AC_CONFIG_ALWAYS_CC_NO_OMIT_FRAME_POINTER
 	ZFS_AC_CONFIG_ALWAYS_CC_NO_IPA_SRA
+	ZFS_AC_CONFIG_ALWAYS_KERNEL_CC_NO_IPA_SRA
 	ZFS_AC_CONFIG_ALWAYS_CC_ASAN
 	ZFS_AC_CONFIG_ALWAYS_TOOLCHAIN_SIMD
 	ZFS_AC_CONFIG_ALWAYS_SYSTEM

module/Kbuild.in

@@ -44,4 +44,5 @@ endif
 subdir-asflags-y := $(ZFS_MODULE_CFLAGS) $(ZFS_MODULE_CPPFLAGS)
 subdir-ccflags-y := $(ZFS_MODULE_CFLAGS) $(ZFS_MODULE_CPPFLAGS)
 
+
 endif

module/icp/algs/edonr/edonr.c

@@ -343,9 +343,11 @@ Q256(size_t bitlen, const uint32_t *data, uint32_t *restrict p)
  * which only goes over it by a hair (1248 bytes on ARM32).
  */
 #include <sys/isa_defs.h>	/* for _ILP32 */
-#ifdef _ILP32   /* We're 32-bit, assume small stack frames */
+#if defined(_ILP32)   /* We're 32-bit, assume small stack frames */
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic ignored "-Wframe-larger-than="
 #endif
+#endif
 
 #if defined(__IBMC__) && defined(_AIX) && defined(__64BIT__)
 static inline size_t

module/icp/algs/skein/skein_block.c

@@ -30,7 +30,9 @@
  * the #pragma here to ignore the warning.
  */
 #if defined(_ILP32) || defined(__powerpc)	/* Assume small stack */
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic ignored "-Wframe-larger-than="
+#endif
 /*
  * We're running on 32-bit, don't unroll loops to save stack frame space
  *

module/lua/ldo.c

@@ -197,7 +197,8 @@ l_noret luaD_throw (lua_State *L, int errcode) {
   }
 }
 
-#if defined(HAVE_INFINITE_RECURSION)
+#if defined(__GNUC__) && !defined(__clang__) && \
+	defined(HAVE_INFINITE_RECURSION)
 #pragma GCC diagnostic pop
 #endif
 

module/os/linux/spl/spl-generic.c

@@ -225,8 +225,10 @@ __div_u64(uint64_t u, uint32_t v)
  * replacements for libgcc-provided functions and will never be called
  * directly.
  */
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wmissing-prototypes"
+#endif
 
 /*
  * Implementation of 64-bit unsigned division for 32-bit machines.
@@ -425,7 +427,9 @@ __aeabi_ldivmod(int64_t u, int64_t v)
 EXPORT_SYMBOL(__aeabi_ldivmod);
 #endif /* __arm || __arm__ */
 
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic pop
+#endif
 
 #endif /* BITS_PER_LONG */
 

module/zcommon/Makefile.in

@@ -26,3 +26,7 @@ $(MODULE)-$(CONFIG_X86) += zfs_fletcher_intel.o
 $(MODULE)-$(CONFIG_X86) += zfs_fletcher_sse.o
 $(MODULE)-$(CONFIG_X86) += zfs_fletcher_avx512.o
 $(MODULE)-$(CONFIG_ARM64) += zfs_fletcher_aarch64_neon.o
+
+ifeq ($(CONFIG_ARM64),y)
+CFLAGS_REMOVE_zfs_fletcher_aarch64_neon.o += -mgeneral-regs-only
+endif

module/zfs/Makefile.in

@@ -154,4 +154,9 @@ ifeq ($(CONFIG_ALTIVEC),y)
 $(obj)/vdev_raidz_math_powerpc_altivec.o: c_flags += -maltivec
 endif
 
+ifeq ($(CONFIG_ARM64),y)
+CFLAGS_REMOVE_vdev_raidz_math_aarch64_neon.o += -mgeneral-regs-only
+CFLAGS_REMOVE_vdev_raidz_math_aarch64_neonx2.o += -mgeneral-regs-only
+endif
+
 include $(mfdir)/../os/linux/zfs/Makefile