On 8/1/23 07:56, Arnd Bergmann wrote:
On Tue, Aug 1, 2023, at 16:23, Naresh Kamboju wrote:
On Tue, 1 Aug 2023 at 18:53, Bart Van Assche <bvanassche@xxxxxxx> wrote:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230801/testrun/18754886/suite/build/test/gcc-8-defconfig/log
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230801/testrun/18754886/suite/build/test/gcc-8-defconfig/details/
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230801/testrun/18754886/suite/build/test/gcc-8-defconfig/history/
I can't reproduce this build error with a gcc-12 arm64 cross-compiler. How
important is gcc-8 for the ARM community?
You are right,
gcc-12 build pass.
gcc-8 build failed.
I can also reproduce this with gcc-9.5.0 from
https://mirrors.edge.kernel.org/pub/tools/crosstool/ but
not with 10.5.0 or clang.
I get the same results for x86 with gcc-9.5.0.
See https://godbolt.org/z/GjGrW9znc for a partially reduced testcase.
Thanks Arnd, this is very helpful. The first error message reported for that
test case is as follows:
<source>:34:286: error: call to '__compiletime_assert_655' declared with attribute error: BUILD_BUG_ON failed: ((u8 *)&(struct request_desc_header){ .enable_crypto = 1})[2] != 0x80
34 | do { __attribute__((__noreturn__)) extern void __compiletime_assert_655(void) __attribute__((__error__("BUILD_BUG_ON failed: " "((u8 *)&(struct request_desc_header){ .enable_crypto = 1})[2] != 0x80")));
if (!(!(((u8 *)&(struct request_desc_header){ .enable_crypto = 1})[2] != 0x80))) __compiletime_assert_655(); } while (0);
|
If I change the return type of ufshcd_check_header_layout() from void
into unsigned int and insert the following at the start of that function:
return ((u8 *)&(struct request_desc_header){ .enable_crypto = 1})[2] != 0x80;
then the compiler shows the following in the output window:
xorl %eax, %eax
In other words, the expression next to the return statement evaluates to zero
but the same expression does not evaluate to zero in the BUILD_BUG_ON()
statement. Does this perhaps indicate a compiler bug? And if so, what is the
appropriate way to fix the build error? Insert an #ifdef/#endif pair inside
ufshcd_check_header_layout() such that the compile-time checks do not happen
for gcc version 9 or older?
Thanks,
Bart.
