On 01/14/2013 02:31 PM, Dmitri Gribenko wrote:
This appears to be an error now. On an older version at home it was just a warning.On Mon, Jan 14, 2013 at 8:42 AM, Reed Kotler <[email protected]> wrote:Forget to say that I need to have this patch reviewd.+__attribute((nomips16)) int a; // expected-warning {{attribute only applies to functions}}
I'll make it an error.
What surprised me is that there are some special rules in gcc related to mips16 and nomips16 when it comes to attribute merging. I'd prefer to sort this out later.
Here is essentially the issue.Normally mips16 is an inhertitable attribute. However, if you add one of the attributes of mips16 or nomips16 to a function, then all function definitions or declarations must also
have that attribute. i.e. void __attribute__((nomips16, otherattribute1)) foo(); void __attribute__((nomips16, otherattribute2)) foo(); is okay. but in any case: void __attribute((nomips16) foo(); void foo(); is not okay.I want to bring this up with the gcc developers before mimicking this behavior in clang. This is the ONLY place in gcc that I could find where this kind of semantics for attributes occurs.
This seems like a bug to me. I had checked the otherrkotler@ubuntu-rkotler:~/testmips16$ mips-linux-gnu-gcc ~/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c -S /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:5:1: error: 'foo32' redeclared with conflicting 'nomips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:6:1: error: 'foo16' redeclared with conflicting 'mips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:10:1: error: 'foo32_' redeclared with conflicting 'nomips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:11:1: error: 'foo16_' redeclared with conflicting 'mips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:14:1: error: 'foo32__' redeclared with conflicting 'mips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:14:1: error: 'foo32__' redeclared with conflicting 'nomips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:16:1: error: wrong number of arguments specified for 'nomips16' attribute /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:16:1: error: 'foo32' redeclared with conflicting 'nomips16' attributes /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:17:1: error: wrong number of arguments specified for 'mips16' attribute /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:19:1: error: wrong number of arguments specified for 'nomips16' attribute /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:20:1: error: wrong number of arguments specified for 'mips16' attribute /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_allowed.c:23:1: error: 'nomips16' attribute only applies to functions
I am concerned by the fact that this is just a warning -- I would
suggest to make it an error. This is a new attribute, so there's no
code abusing this attribute (we don't need to be compatible with it).
What does gcc do?
+void __attribute__((nomips16)) foo32(); // expected-warning {{unknown
attribute 'nomips16' ignored}}
This is what gcc does. (here I'm compiling on linux x86).rkotler@ubuntu-rkotler:~/testmips16$ gcc ~/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_not_allowed.c -S /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_not_allowed.c:3: warning: ‘nomips16’ attribute directive ignored /home/rkotler/workspace/llvmpb3/tools/clang/test/Sema/mips16_attr_not_allowed.c:4: warning: ‘mips16’ attribute directive ignored
Same here. What does gcc do in this case? (I know that this behavior can not be changed without some refactoring. But if GCC gives an error, we should, too. So we would leave a comment in the test, or better -- do the required refactoring...) Dmitri
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