From a932de71457e16030d7d05e4230c56e231c7a8e9 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Wed, 26 Aug 2026 23:48:41 +0800
Subject: [CodeGen] Run scheduling transformations once

---
 backend/lib/CodeGen/PostRAScheduler.cpp | 44 +++------------------------------
 1 file changed, 3 insertions(+), 41 deletions(-)

(limited to 'backend/lib/CodeGen/PostRAScheduler.cpp')

diff --git a/backend/lib/CodeGen/PostRAScheduler.cpp b/backend/lib/CodeGen/PostRAScheduler.cpp
index 7f5c697..d8c6a36 100644
--- a/backend/lib/CodeGen/PostRAScheduler.cpp
+++ b/backend/lib/CodeGen/PostRAScheduler.cpp
@@ -7,7 +7,6 @@
 #include "rcc/CodeGen/LiveVariables.h"
 #include "rcc/CodeGen/MachineBasicBlock.h"
 #include "rcc/CodeGen/MachineFunction.h"
-#include "rcc/CodeGen/MachineFunctionCloner.h"
 #include "rcc/CodeGen/MachineInstr.h"
 #include "rcc/CodeGen/MachineOperand.h"
 #include "rcc/CodeGen/RegisterMask.h"
@@ -19,9 +18,7 @@
 #include <bit>
 #include <cstddef>
 #include <cstdint>
-#include <optional>
 #include <ranges>
-#include <string>
 #include <utility>
 #include <vector>
 
@@ -56,51 +53,16 @@ const MachinePassContract &PostRASchedulerPass::contract() const noexcept {
 Expected<MachinePassResult> PostRASchedulerPass::run(MachineFunction &Function,
                                                      const TargetDescription &Target,
                                                      MachineFunctionAnalysisManager &Analyses) {
-  auto Trial = cloneMachineFunction(
-      Function, Target,
-      MachineFunctionCloneOptions{.NewStableID = Function.stableID(), .NewName = std::nullopt});
-  if (!Trial) {
-    return std::unexpected(
-        withErrorContext(Trial.error(), "post-RA scheduler transaction setup failed: "));
-  }
-  MachineFunctionAnalysisManager TrialAnalyses;
-  auto TrialLiveness =
-      TrialAnalyses.getResult<LiveVariablesAnalysis>(*Trial->ClonedFunction, Target);
-  if (!TrialLiveness)
-    return std::unexpected(TrialLiveness.error());
-  auto TrialFrequencies =
-      TrialAnalyses.getResult<MachineBlockFrequencyAnalysis>(*Trial->ClonedFunction, Target);
-  if (!TrialFrequencies)
-    return std::unexpected(TrialFrequencies.error());
-  MachineActionReplay Actions(Analyses, Trial->InstructionStableIDs);
-  MachineSchedulerOptions TrialOptions = Options;
-  TrialOptions.EmitDebugOutput = false;
-  auto TrialRun = runMachineScheduler(*Trial->ClonedFunction, Target, *Model,
-                                      ScheduleDAGMode::PostRegisterAllocation, **TrialLiveness,
-                                      **TrialFrequencies, TrialOptions, &Actions);
-  if (!TrialRun)
-    return std::unexpected(TrialRun.error());
-  auto TrialRepair =
-      repairPostRAMachineBlockLiveness(TrialRun->ChangedBlocks, Target, **TrialLiveness);
-  if (!TrialRepair)
-    return std::unexpected(TrialRepair.error());
-
   auto Liveness = Analyses.getResult<LiveVariablesAnalysis>(Function, Target);
   if (!Liveness)
     return std::unexpected(Liveness.error());
   auto Frequencies = Analyses.getResult<MachineBlockFrequencyAnalysis>(Function, Target);
   if (!Frequencies)
     return std::unexpected(Frequencies.error());
-  Actions.beginReplay();
   auto Run = runMachineScheduler(Function, Target, *Model, ScheduleDAGMode::PostRegisterAllocation,
-                                 **Liveness, **Frequencies, Options, &Actions);
-  if (!Run) {
-    return std::unexpected(withErrorContext(
-        Run.error(), "post-RA scheduler diverged after a successful transaction preflight: "));
-  }
-  auto Replayed = Actions.finishReplay();
-  if (!Replayed)
-    return std::unexpected(Replayed.error());
+                                 **Liveness, **Frequencies, Options, Analyses);
+  if (!Run)
+    return std::unexpected(Run.error());
   auto Repaired = repairPostRAMachineBlockLiveness(Run->ChangedBlocks, Target, **Liveness);
   if (!Repaired)
     return std::unexpected(Repaired.error());
-- 
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