[AMDGPU] Remove #if 0 code for fences in SIInsertWaitcnts (#92902)

We insert required waits for fences in SIMemoryLegalizer.

Author: jayfoad

llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp

@@ -1673,59 +1673,6 @@ bool SIInsertWaitcnts::generateWaitcntInstBefore(MachineInstr &MI,
             AMDGPU::SendMsg::ID_GS_DONE_PreGFX11)) {
     Wait.LoadCnt = 0;
   }
-#if 0 // TODO: the following blocks of logic when we have fence.
-  else if (MI.getOpcode() == SC_FENCE) {
-    const unsigned int group_size =
-      context->shader_info->GetMaxThreadGroupSize();
-    // group_size == 0 means thread group size is unknown at compile time
-    const bool group_is_multi_wave =
-      (group_size == 0 || group_size > target_info->GetWaveFrontSize());
-    const bool fence_is_global = !((SCInstInternalMisc*)Inst)->IsGroupFence();
-
-    for (unsigned int i = 0; i < Inst->NumSrcOperands(); i++) {
-      SCRegType src_type = Inst->GetSrcType(i);
-      switch (src_type) {
-        case SCMEM_LDS:
-          if (group_is_multi_wave ||
-            context->OptFlagIsOn(OPT_R1100_LDSMEM_FENCE_CHICKEN_BIT)) {
-            EmitWaitcnt |= ScoreBrackets->updateByWait(DS_CNT,
-                               ScoreBrackets->getScoreUB(DS_CNT));
-            // LDS may have to wait for VMcnt after buffer load to LDS
-            if (target_info->HasBufferLoadToLDS()) {
-              EmitWaitcnt |= ScoreBrackets->updateByWait(LOAD_CNT,
-                                 ScoreBrackets->getScoreUB(LOAD_CNT));
-            }
-          }
-          break;
-
-        case SCMEM_GDS:
-          if (group_is_multi_wave || fence_is_global) {
-            EmitWaitcnt |= ScoreBrackets->updateByWait(EXP_CNT,
-              ScoreBrackets->getScoreUB(EXP_CNT));
-            EmitWaitcnt |= ScoreBrackets->updateByWait(DS_CNT,
-              ScoreBrackets->getScoreUB(DS_CNT));
-          }
-          break;
-
-        case SCMEM_UAV:
-        case SCMEM_TFBUF:
-        case SCMEM_RING:
-        case SCMEM_SCATTER:
-          if (group_is_multi_wave || fence_is_global) {
-            EmitWaitcnt |= ScoreBrackets->updateByWait(EXP_CNT,
-              ScoreBrackets->getScoreUB(EXP_CNT));
-            EmitWaitcnt |= ScoreBrackets->updateByWait(LOAD_CNT,
-              ScoreBrackets->getScoreUB(LOAD_CNT));
-          }
-          break;
-
-        case SCMEM_SCRATCH:
-        default:
-          break;
-      }
-    }
-  }
-#endif
 
   // Export & GDS instructions do not read the EXEC mask until after the export
   // is granted (which can occur well after the instruction is issued).