added files for eliminating identity

src/CMakeLists.txt

@@ -10,6 +10,7 @@ add_library(migraphx
     eliminate_allocation.cpp
     eliminate_contiguous.cpp
     eliminate_concat.cpp
+    eliminate_identity.cpp
     fwd_conv_batchnorm_rewrite.cpp
     rewrite_rnn.cpp
     env.cpp

src/eliminate_identity.cpp

+#include <migraphx/eliminate_identity.hpp>
+#include <migraphx/program.hpp>
+#include <migraphx/instruction.hpp>
+#include <migraphx/operators.hpp>
+#include <migraphx/iterator_for.hpp>
+#include <migraphx/ranges.hpp>
+#include <migraphx/stringutils.hpp>
+#include <utility>
+
+namespace migraphx {
+inline namespace MIGRAPHX_INLINE_NS {
+
+
+void eliminate_identity::apply(program& p) const
+{
+    for(auto ins : iterator_for(p))
+    {
+        if(ins->get_operator().name() == "identity")
+        {
+            if(ins != p.end())
+            {
+                instruction_ref identity_input{ins->inputs().at(0)};
+                auto next_ins = std::next(ins);
+                std::vector<instruction_ref> next_ins_inputs{next_ins->inputs()};
+                for (auto& input : next_ins_inputs)
+                {
+                    if(input == ins)
+                    {
+                        input = identity_input;
+                    }
+                }
+                p.replace_instruction(next_ins, next_ins->get_operator(), next_ins_inputs);
+            }
+        }
+    }
+}
+
+} // namespace MIGRAPHX_INLINE_NS
+} // namespace migraphx

src/include/migraphx/eliminate_identity.hpp

+#ifndef MIGRAPHX_GUARD_RTGLIB_ELIMINATE_IDENTITY_HPP
+#define MIGRAPHX_GUARD_RTGLIB_ELIMINATE_IDENTITY_HPP
+
+#include <string>
+#include <migraphx/instruction_ref.hpp>
+#include <migraphx/config.hpp>
+
+namespace migraphx {
+inline namespace MIGRAPHX_INLINE_NS {
+
+struct program;
+
+/**
+ * Remove identity instructions.
+ */
+struct eliminate_identity
+{
+    std::string name() const { return "eliminate_identity"; }
+    void apply(program& p) const;
+};
+
+} // namespace MIGRAPHX_INLINE_NS
+} // namespace migraphx
+
+#endif

src/targets/gpu/target.cpp

@@ -17,6 +17,7 @@
 #include <migraphx/fwd_conv_batchnorm_rewrite.hpp>
 #include <migraphx/rewrite_rnn.hpp>
 #include <migraphx/eliminate_concat.hpp>
+#include <migraphx/eliminate_identity.hpp>
 #include <migraphx/gpu/concat_gpu_opt.hpp>
 
 namespace migraphx {
@@ -30,6 +31,7 @@ std::vector<pass> target::get_passes(migraphx::context& gctx) const
     return
     {
         dead_code_elimination{},
+        eliminate_identity{},
         fwd_conv_batchnorm_rewrite{},
         dead_code_elimination{},
         rewrite_rnn{},