[PATCH] D24669: {Sema] Gcc compatibility of vector shift.

[Bruno Cardoso Lopes via cfe-commits]

bruno added inline comments.


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Comment at: llvm/tools/clang/lib/Sema/SemaExpr.cpp:8787
     }
+    if (!S.LangOpts.OpenCL && !S.LangOpts.ZVector) {
+      const BuiltinType *LHSBT = LHSEleType->getAs<clang::BuiltinType>();
----------------
vbyakovlcl wrote:
> bruno wrote:
> > vbyakovlcl wrote:
> > > bruno wrote:
> > > > Besides `__ext_vector_type__`, would this also trigger for `vector_size`? Right now this is an error for `vector_size` primarily because the number of elements is different, can you confirm this won't change?
> > > I compare vector element sizes, so there must not be any differencies caused by different triggers. I added additional type definitions to the tests. All compiles fain.
> > 
> > I don't think this is right. When I try to compile similar code for `vector_size` without your patch, I get the errors:
> > 
> > /tmp/x.c:80:15: error: vector operands do not have the same number of elements ('vector_int8n' (vector of 2 'int' values) and 'vector_uchar8n' (vector of 8 'unsigned char' values))
> >   vi8n = vi8n << vuc8n; // expected-warning {{vector operands do not have the same elements sizes}}
> >          ~~~~ ^  ~~~~~
> > /tmp/x.c:81:17: error: vector operands do not have the same number of elements ('vector_uchar8n' (vector of 8 'unsigned char' values) and 'vector_int8n' (vector of 2 'int' values))
> >   vuc8n = vuc8n << vi8n; // expected-warning {{vector operands do not have the same elements sizes}}
> >           ~~~~~ ^  ~~~~
> > /tmp/x.c:82:17: error: vector operands do not have the same number of elements ('vector_ushort8n' (vector of 4 'unsigned short' values) and 'vector_uint8n' (vector of 2 'unsigned int' values))
> >   vus8n = vus8n << vui8n; // expected-warning {{vector operands do not have the same elements sizes}}
> >           ~~~~~ ^  ~~~~~
> > /tmp/x.c:83:17: error: vector operands do not have the same number of elements ('vector_uint8n' (vector of 2 'unsigned int' values) and 'vector_short8n' (vector of 4 'short' values))
> >   vui8n = vui8n << vs8n; // expected-warning {{vector operands do not have the same elements sizes}}
> >           ~~~~~ ^  ~~~~ 
> > 
> > Given your test changes, it seems that now, instead of "vector operands do not have the same number of elements" we would get "vector operands do not have the same elements sizes". I rather we stay with the first. Additionally, even if we had "vector operands do not have the same elements sizes" for `vector_size`, this should never be demoted to a warning.
> Argument of a GNU vector size attribute specifies vector size measured in bytes(see https://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html). So you got right diagnostics. Both compilers with and without my changes print the same diagnostics  for yours case. Here is a small testcase used both GNU and clang extensions
> 
> $ cat bruno.c                                                                                                                                                                                                        
> typedef __attribute__((__ext_vector_type__(8))) int vector_int8;
> typedef __attribute__((__ext_vector_type__(8))) unsigned char vector_uchar8;
>  
> typedef __attribute__((vector_size(8))) int vector_int8n;
> typedef __attribute__((vector_size(8))) unsigned char vector_uchar8n;
>  
> vector_int8  vi8;
> vector_uchar8 vuc8;
> vector_int8n  vi8n;
> vector_uchar8n vuc8n;
>  
> int foo() {
>   vi8 = vi8 << vuc8;
>   vi8n = vi8n << vuc8n;
> 
> $ clang -c bruno.c -Wno-error-vec-elem-size                                                                                                                                                                          
> bruno.c:13:13: warning: vector operands do not have the same elements sizes ('vector_int8' (vector of 8 'int' values) and 'vector_uchar8' (vector of 8 'unsigned char' values)) [-Wvec-elem-size]
>   vi8 = vi8 << vuc8;
>         ~~~ ^  ~~~~
> bruno.c:14:15: error: vector operands do not have the same number of elements ('vector_int8n' (vector of 2 'int' values) and 'vector_uchar8n' (vector of 8 'unsigned char' values))
>   vi8n = vi8n << vuc8n;
> 
> The compiler without the changes prints the second error only (bruno.c:14:15).
What actually concerns me here is the following: if you invoke `clang -c bruno.c -Wvec-elem-size`, will that override the `error: vector operands do not have the same number of elements ` message for `vector_size` typed vectors? If so, I don't think this is right.


https://reviews.llvm.org/D24669