[TIR][USMP] Greedy algorithms for USMP

Changed sorting criteria use alphabetic
ordering as opposed to hashes of string
as it seemed different accross different
platforms.

Change-Id: Ia7938d1b0d1374924c3ec7287526ccf374c54eb7

Author: manupak

src/tir/usmp/algo/greedy.cc

@@ -167,9 +167,7 @@ class GreedySize : public GreedyBase {
               [](const BufferInfo& a, const BufferInfo& b) {
                 if (a->size_bytes->value == b->size_bytes->value) {
                   if (a->conflicts.size() == b->conflicts.size()) {
-                    auto a_name_hash = std::hash<std::string>{}(a->name_hint->data);
-                    auto b_name_hash = std::hash<std::string>{}(b->name_hint->data);
-                    return a_name_hash > b_name_hash;
+                    return std::string(a->name_hint->data) > std::string(b->name_hint->data);
                   } else {
                     return a->conflicts.size() > b->conflicts.size();
                   }
@@ -198,9 +196,7 @@ class GreedyConflicts : public GreedyBase {
               [](const BufferInfo& a, const BufferInfo& b) {
                 if (a->conflicts.size() == b->conflicts.size()) {
                   if (a->size_bytes->value == b->size_bytes->value) {
-                    auto a_name_hash = std::hash<std::string>{}(a->name_hint->data);
-                    auto b_name_hash = std::hash<std::string>{}(b->name_hint->data);
-                    return a_name_hash > b_name_hash;
+                    return std::string(a->name_hint->data) > std::string(b->name_hint->data);
                   } else {
                     return a->size_bytes->value > b->size_bytes->value;
                   }

tests/python/unittest/test_tir_usmp_algo.py

@@ -149,9 +149,9 @@ def _test():
         buffer_info_arr = [bi_a, bi_b, bi_c]
         fusmp_algo = tvm.get_global_func(f"tir.usmp.algo.{algorithm}")
         buffer_pool_allocations = fusmp_algo(buffer_info_arr)
-        assert buffer_pool_allocations[bi_a].byte_offset == 0
-        assert buffer_pool_allocations[bi_b].byte_offset == 20
-        assert buffer_pool_allocations[bi_c].byte_offset == 10
+        assert buffer_pool_allocations[bi_a].byte_offset == 20
+        assert buffer_pool_allocations[bi_b].byte_offset == 10
+        assert buffer_pool_allocations[bi_c].byte_offset == 0
 
     # This is tested for several times to check stability
     for x in range(0, 10):