Add examples of Gemm (data type: int4) (#367)

* Add GEMM examples for int4

Currently the source files are just copied from int8 examples

* Re-use pre-defined alias in int4 exmples

* Distinguish user-side type from kernel-side type

* Add int4_t support for check_err()

* Allow conversion between Tensor<> specializations

* Re-format source files

* Use different type for host tensors

* Re-use CopyAsType<>() to implement copy ctor

* Re-use element-wise operation type alias

* Fix typo in alias names

* Complete the int4 examples

* Add constraint to Tensor<> templated methods

* Add type traits 'is_signed_integral<>'

* Add type constraints for integer version check_err<>()

* Allow comparing different-sized integral types in check_err()

* Check converted Tensor<int4_t> with golden Tensor<int8_t>

* Remove constraint of Tensor<>::CopyAsType()

* Avoid compilation error while disabling ck::int4_t support

* Remove debug messages

* Add #error directive to prevent compile sources with wrong setting

* Simplify tensor usages in examples

* Add constraint to check_err() input reference type

* Align design with other PR

* Use ""_uz to simplify example code

* Avoid too much generalizing check_err()

* Re-format GEMM instance template arguments

* Extract int4 example common codes

* Sort include directives

* Move #include directives into new header

* Move common codes together

* Re-format template argument in example code

* Reuse same implementation code for most of GEMM examples

* Re-format common.hpp

* Unify structured comment in examples

* Use reinterpret_cast<>() for cross-type pointer conversion

* Revert "Add type traits 'is_signed_integral<>'"

This reverts commit f2c148efae.

* Allow unsigned integer arguments for check_err()

* Fix compilation error in check_err()

* Remove unnecessary copy ctor for Tensor<>

* Mark Tensor<> special member functions as 'default'

* Use more strict condition to add code in examples

* Fix wrong program return value of GEMM examples

* Handle the case while user specify all the strides

* Fix never-ran examples

* Exit successfully if GEMM instance does not support given problem

* Add missing 'else' keyword

* Re-format CMakeLists.txt

* Add wrapper function to hide value conversion while copying memory

* Add new DeviceMem API to copy memory

* Use new DeviceMem API to implement examples

* Revert "Add new DeviceMem API to copy memory"

This reverts commit 3f190b0779.

* Add conversion ctor for Tensor<>

* Write Tensor<> conversion logics explicitly in example code

* Convert Tensor<> values after transfer data to host

library/include/ck/library/utility/check_err.hpp

@@ -15,6 +15,7 @@
 
 #include "ck/ck.hpp"
 #include "ck/utility/data_type.hpp"
+#include "ck/utility/type.hpp"
 #include "ck/host_utility/io.hpp"
 
 namespace ck {
@@ -164,7 +165,7 @@ check_err(const std::vector<T>& out,
 {
     if(out.size() != ref.size())
     {
-        std::cout << msg << " out.size() != ref.size(), :" << out.size() << " != " << ref.size()
+        std::cerr << msg << " out.size() != ref.size(), :" << out.size() << " != " << ref.size()
                   << std::endl;
         return false;
     }
@@ -185,8 +186,7 @@ check_err(const std::vector<T>& out,
             err_count++;
             if(err_count < 5)
             {
-                std::cout << msg << " out[" << i << "] != ref[" << i
-                          << "]: " << static_cast<int>(out[i]) << " != " << static_cast<int>(ref[i])
+                std::cerr << msg << " out[" << i << "] != ref[" << i << "]: " << o << " != " << r
                           << std::endl;
             }
             res = false;