Simplify algebra of negative division operations

Part of changes that go wtih #1236. Reverts -1 divide operations to a simple negation of the parameter

src/simplify_algebra.cpp

@@ -895,6 +895,20 @@ struct find_neg_unit_mult_const
     }
 };
 
+struct find_neg_unit_div_const
+{
+    auto matcher() const { return match::name("div")(match::arg(1)(match::has_value(-1.0f))); }
+
+    void apply(module& m, const match::matcher_result& r) const
+    {
+        auto ins  = r.result;
+        auto args = ins->inputs();
+        auto neg  = m.add_instruction(make_op("neg"), args.front());
+
+        m.replace_instruction(ins, neg);
+    }
+};
+
 struct find_sub_const
 {
     auto matcher() const
@@ -1093,6 +1107,7 @@ void simplify_algebra::apply(module& m) const
                             find_mul_slice_conv{},
                             find_mul_add{},
                             find_unit_ops{},
+                            find_neg_unit_div_const{},
                             find_div_const{},
                             find_sub_const{},
                             find_rsqrt{},

test/simplify_algebra_test.cpp

@@ -835,6 +835,25 @@ TEST_CASE(simplify_neg_unit_mult_const)
     EXPECT((m1 == m3) && (m1 == m2));
 }
 
+TEST_CASE(simplify_neg_unit_div_const)
+{
+    migraphx::module m1;
+    {
+        auto x    = m1.add_parameter("x", {migraphx::shape::int32_type, {1}});
+        auto unit = m1.add_literal(-1);
+        m1.add_instruction(migraphx::make_op("div"), x, unit);
+    }
+    run_pass(m1);
+
+    migraphx::module m2;
+    {
+        auto x = m2.add_parameter("x", {migraphx::shape::int32_type, {1}});
+        m2.add_instruction(migraphx::make_op("neg"), x);
+    }
+
+    EXPECT(m1 == m2);
+}
+
 TEST_CASE(simplify_sub_const)
 {
     migraphx::module m1;