cse literal fix (#524)

* add new test

* formatting

* remove comments

* fix comment and use contains

* formatting
Co-authored-by: mvermeulen <5479696+mvermeulen@users.noreply.github.com>

src/eliminate_common_subexpression.cpp

@@ -14,19 +14,24 @@ template <class Range>
 void cse_range(program& p, Range&& r)
 {
     std::unordered_multimap<std::string, instruction_ref> instructions;
+    std::unordered_set<instruction_ref> processed_ins;
     for(auto ins : r)
     {
         // Skip dead instructions
         if(ins->outputs().empty())
             continue;
+
         // Find instruction with the same name
         auto found_instructions = range(instructions.equal_range(ins->name()));
         for(const auto& pp : found_instructions)
         {
             auto eq = pp.second;
+            if(contains(processed_ins, eq))
+                continue;
             if(*eq != *ins)
                 continue;
             p.replace_instruction(ins, eq);
+            processed_ins.emplace(ins);
             auto outputs = eq->outputs();
             std::sort(outputs.begin(), outputs.end(), [&](auto x, auto y) {
                 return std::distance(eq, x) < std::distance(eq, y);

test/eliminate_common_subexpression_test.cpp

@@ -109,4 +109,36 @@ TEST_CASE(cse_test4)
     EXPECT(p1 == p2);
 }
 
+TEST_CASE(cse_test_literal)
+{
+    migraphx::program p1;
+    {
+        auto six1  = p1.add_literal(6);
+        auto zero1 = p1.add_literal(0);
+        auto six2  = p1.add_literal(6);
+        auto zero2 = p1.add_literal(0);
+        auto six3  = p1.add_literal(6);
+        auto zero3 = p1.add_literal(0);
+
+        auto sum1 = p1.add_instruction(migraphx::op::add{}, six1, zero1);
+        auto sum2 = p1.add_instruction(migraphx::op::add{}, six2, zero2);
+        auto sum3 = p1.add_instruction(migraphx::op::add{}, six3, zero3);
+        auto sum4 = p1.add_instruction(migraphx::op::add{}, sum1, sum2);
+        auto sum5 = p1.add_instruction(migraphx::op::add{}, sum3, sum4);
+        p1.add_instruction(pass_op{}, sum5);
+    }
+    run_pass(p1);
+
+    migraphx::program p2;
+    {
+        auto six  = p2.add_literal(6);
+        auto zero = p2.add_literal(0);
+        auto sum1 = p2.add_instruction(migraphx::op::add{}, six, zero);
+        auto sum2 = p2.add_instruction(migraphx::op::add{}, sum1, sum1);
+        auto sum3 = p2.add_instruction(migraphx::op::add{}, sum1, sum2);
+        p2.add_instruction(pass_op{}, sum3);
+    }
+    EXPECT(p1 == p2);
+}
+
 int main(int argc, const char* argv[]) { test::run(argc, argv); }