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mips: Fix unroll macro when building with Clang

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Building with Clang errors after commit 6baaeadae9 ("MIPS: Provide
unroll() macro, use it for cache ops") since the GCC_VERSION macro
is defined in include/linux/compiler-gcc.h, which is only included
in compiler.h when using GCC:

In file included from arch/mips/kernel/mips-mt.c:20:
./arch/mips/include/asm/r4kcache.h:254:1: error: use of undeclared
identifier 'GCC_VERSION'; did you mean 'S_VERSION'?
__BUILD_BLAST_CACHE(i, icache, Index_Invalidate_I, Hit_Invalidate_I, 32,
)
^
./arch/mips/include/asm/r4kcache.h:219:4: note: expanded from macro
'__BUILD_BLAST_CACHE'
                        cache_unroll(32, kernel_cache, indexop,
                        ^
./arch/mips/include/asm/r4kcache.h:203:2: note: expanded from macro
'cache_unroll'
        unroll(times, _cache_op, insn, op, (addr) + (i++ * (lsize)));
        ^
./arch/mips/include/asm/unroll.h:28:15: note: expanded from macro
'unroll'
        BUILD_BUG_ON(GCC_VERSION >= 40700 &&                    \
                     ^

Use CONFIG_GCC_VERSION, which will always be set by Kconfig.
Additionally, Clang 8 had improvements around __builtin_constant_p so
use that as a lower limit for this check with Clang (although MIPS
wasn't buildable until Clang 9); building a kernel with Clang 9.0.0
has no issues after this change.

Fixes: 6baaeadae9 ("MIPS: Provide unroll() macro, use it for cache ops")
Link: https://github.com/ClangBuiltLinux/linux/issues/736
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Cc: Nick Desaulniers <ndesaulniers@google.com>
This commit is contained in:
Nathan Chancellor 2019-10-10 13:31:59 -07:00 committed by Paul Burton
parent 7784cac697
commit df3da04880
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1 changed files with 2 additions and 1 deletions
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3
arch/mips/include/asm/unroll.h
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@ -25,7 +25,8 @@
* generate reasonable code for the switch statement, \
* so we skip the sanity check for those compilers. \
*/ \
BUILD_BUG_ON(GCC_VERSION >= 40700 && \
BUILD_BUG_ON((CONFIG_GCC_VERSION >= 40700 || \
CONFIG_CLANG_VERSION >= 80000) && \
!__builtin_constant_p(times)); \
\
switch (times) { \