From f7df62b40fd06585bb8c93d001f90e37d3aea3c2 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Wed, 19 Aug 2026 17:16:32 +0800
Subject: [CodeGen] Remove unsupported pre-PEI pseudo expansion

---
 .../include/rcc/CodeGen/InstructionDescriptor.h    |  1 -
 .../include/rcc/CodeGen/MachinePseudoExpansion.h   | 14 --------
 .../include/rcc/CodeGen/TargetPseudoExpansion.h    |  1 -
 .../lib/CodeGen/MachineOptimizationPipeline.cpp    |  3 --
 backend/lib/CodeGen/MachinePseudoExpansion.cpp     | 38 ++--------------------
 .../utils/TableGen/Common/CodeGenInstruction.cpp   |  3 +-
 6 files changed, 3 insertions(+), 57 deletions(-)

diff --git a/backend/include/rcc/CodeGen/InstructionDescriptor.h b/backend/include/rcc/CodeGen/InstructionDescriptor.h
index 91881e6..b172cd9 100644
--- a/backend/include/rcc/CodeGen/InstructionDescriptor.h
+++ b/backend/include/rcc/CodeGen/InstructionDescriptor.h
@@ -197,7 +197,6 @@ enum class PseudoOwner : std::uint8_t {
   TwoAddressRewrite,
   PreRAExpansion,
   RegisterAllocator,
-  PrePEIExpansion,
   PrologueEpilogueInsertion,
   PostRAExpansion,
   Finalization,
diff --git a/backend/include/rcc/CodeGen/MachinePseudoExpansion.h b/backend/include/rcc/CodeGen/MachinePseudoExpansion.h
index c30ba50..3c72307 100644
--- a/backend/include/rcc/CodeGen/MachinePseudoExpansion.h
+++ b/backend/include/rcc/CodeGen/MachinePseudoExpansion.h
@@ -38,20 +38,6 @@ private:
   const TargetPseudoExpansionInfo *Info;
 };
 
-class PrePEITargetPseudoExpansionPass final : public MachineFunctionPass {
-public:
-  explicit PrePEITargetPseudoExpansionPass(const TargetPseudoExpansionInfo &Info) noexcept
-      : Info(&Info) {}
-
-  [[nodiscard]] const MachinePassContract &contract() const noexcept override;
-  [[nodiscard]] Expected<MachinePassResult> run(MachineFunction &Function,
-                                                const TargetDescription &Target,
-                                                MachineFunctionAnalysisManager &Analyses) override;
-
-private:
-  const TargetPseudoExpansionInfo *Info;
-};
-
 class ExpandPostRAPseudosPass final : public MachineFunctionPass {
 public:
   explicit ExpandPostRAPseudosPass(const TargetPseudoExpansionInfo &Info) noexcept : Info(&Info) {}
diff --git a/backend/include/rcc/CodeGen/TargetPseudoExpansion.h b/backend/include/rcc/CodeGen/TargetPseudoExpansion.h
index 5135d78..039b221 100644
--- a/backend/include/rcc/CodeGen/TargetPseudoExpansion.h
+++ b/backend/include/rcc/CodeGen/TargetPseudoExpansion.h
@@ -15,7 +15,6 @@ class TargetDescription;
 
 enum class MachinePseudoExpansionPhase : std::uint8_t {
   PreRA,
-  PrePEI,
   PostRA,
   TargetLate,
 };
diff --git a/backend/lib/CodeGen/MachineOptimizationPipeline.cpp b/backend/lib/CodeGen/MachineOptimizationPipeline.cpp
index dc64b8f..4d20f9a 100644
--- a/backend/lib/CodeGen/MachineOptimizationPipeline.cpp
+++ b/backend/lib/CodeGen/MachineOptimizationPipeline.cpp
@@ -100,9 +100,6 @@ addPostRegisterAllocationPipeline(MachineFunctionPassManager &Pipeline,
   if (!Added)
     return std::unexpected(Added.error());
   Added = addPass<MachineShrinkWrappingPass>(Pipeline, TargetInfo.FrameLowering);
-  if (!Added)
-    return std::unexpected(Added.error());
-  Added = addPass<PrePEITargetPseudoExpansionPass>(Pipeline, TargetInfo.PseudoExpansion);
   if (!Added)
     return std::unexpected(Added.error());
   Added = addPass<PrologueEpilogueInsertionPass>(Pipeline, TargetInfo.FrameLowering);
diff --git a/backend/lib/CodeGen/MachinePseudoExpansion.cpp b/backend/lib/CodeGen/MachinePseudoExpansion.cpp
index 8388079..e81168c 100644
--- a/backend/lib/CodeGen/MachinePseudoExpansion.cpp
+++ b/backend/lib/CodeGen/MachinePseudoExpansion.cpp
@@ -99,9 +99,8 @@ using BlockSizeSnapshot = std::vector<std::pair<MachineBlockStableID, std::uint6
     return makeUnexpected(ErrorCode::PseudoExpansionFailed,
                           "post-selection pseudo expansion created a virtual register");
   }
-  if (Phase != MachinePseudoExpansionPhase::PrePEI &&
-      (Before.FrameObjectCount != After.FrameObjectCount ||
-       Before.FrameFrozen != After.FrameFrozen)) {
+  if (Before.FrameObjectCount != After.FrameObjectCount ||
+      Before.FrameFrozen != After.FrameFrozen) {
     return makeUnexpected(ErrorCode::PseudoExpansionFailed,
                           "post-PEI pseudo expansion changed frozen frame resources");
   }
@@ -112,8 +111,6 @@ using BlockSizeSnapshot = std::vector<std::pair<MachineBlockStableID, std::uint6
   switch (Phase) {
   case MachinePseudoExpansionPhase::PreRA:
     return PseudoOwner::PreRAExpansion;
-  case MachinePseudoExpansionPhase::PrePEI:
-    return PseudoOwner::PrePEIExpansion;
   case MachinePseudoExpansionPhase::PostRA:
     return PseudoOwner::PostRAExpansion;
   case MachinePseudoExpansionPhase::TargetLate:
@@ -155,21 +152,6 @@ using BlockSizeSnapshot = std::vector<std::pair<MachineBlockStableID, std::uint6
                              MachinePassChange::Registers};
     return Value;
   }();
-  static const MachinePassContract PrePEI = [] {
-    MachinePassContract Value{
-        .Name = "pre-pei-target-pseudo-expansion",
-        .Requires = {MachineFunctionProperty::Selected, MachineFunctionProperty::NoPHIs,
-                     MachineFunctionProperty::NoVRegs, MachineFunctionProperty::TracksLiveness},
-        .Sets = {},
-        .Clears = {},
-        .RequiredAnalyses = {},
-        .VerificationStage = PipelineStage::RegisterAllocated,
-    };
-    Value.ThreadSafety = PassThreadSafety::ThreadSafe;
-    Value.DeclaredChanges = {MachinePassChange::Instructions, MachinePassChange::Operands,
-                             MachinePassChange::Frame};
-    return Value;
-  }();
   static const MachinePassContract PostRA = [] {
     MachinePassContract Value{
         .Name = "postrapseudos",
@@ -205,8 +187,6 @@ using BlockSizeSnapshot = std::vector<std::pair<MachineBlockStableID, std::uint6
   switch (Phase) {
   case MachinePseudoExpansionPhase::PreRA:
     return PreRA;
-  case MachinePseudoExpansionPhase::PrePEI:
-    return PrePEI;
   case MachinePseudoExpansionPhase::PostRA:
     return PostRA;
   case MachinePseudoExpansionPhase::TargetLate:
@@ -450,20 +430,6 @@ PreparePostRAPseudosPass::run(MachineFunction &Function, const TargetDescription
   return runPreparationTransaction(Function, Target, *Info, Analyses);
 }
 
-const MachinePassContract &PrePEITargetPseudoExpansionPass::contract() const noexcept {
-  return phaseContract(MachinePseudoExpansionPhase::PrePEI);
-}
-
-Expected<MachinePassResult>
-PrePEITargetPseudoExpansionPass::run(MachineFunction &Function, const TargetDescription &Target,
-                                     MachineFunctionAnalysisManager &Analyses) {
-  if (!Function.properties().containsAll(contract().Requires))
-    return makeUnexpected(ErrorCode::VerificationError,
-                          "pre-PEI pseudo expansion requires allocated tracked-liveness MIR");
-  return runExpansionTransaction(Function, Target, *Info, MachinePseudoExpansionPhase::PrePEI,
-                                 nullptr, Analyses);
-}
-
 const MachinePassContract &ExpandPostRAPseudosPass::contract() const noexcept {
   return phaseContract(MachinePseudoExpansionPhase::PostRA);
 }
diff --git a/backend/utils/TableGen/Common/CodeGenInstruction.cpp b/backend/utils/TableGen/Common/CodeGenInstruction.cpp
index d4dbfee..61c72a2 100644
--- a/backend/utils/TableGen/Common/CodeGenInstruction.cpp
+++ b/backend/utils/TableGen/Common/CodeGenInstruction.cpp
@@ -110,7 +110,7 @@ instructionFlagEnumerator(std::string_view Value) noexcept {
 
 [[nodiscard]] std::optional<std::string_view>
 pseudoOwnerEnumerator(std::string_view Value) noexcept {
-  static constexpr std::array<std::pair<std::string_view, std::string_view>, 13> Owners = {{
+  static constexpr std::array<std::pair<std::string_view, std::string_view>, 12> Owners = {{
       {"none", "None"},
       {"legalizer", "Legalizer"},
       {"register_bank_select", "RegisterBankSelect"},
@@ -119,7 +119,6 @@ pseudoOwnerEnumerator(std::string_view Value) noexcept {
       {"two_address_rewrite", "TwoAddressRewrite"},
       {"pre_ra_expansion", "PreRAExpansion"},
       {"register_allocator", "RegisterAllocator"},
-      {"pre_pei_expansion", "PrePEIExpansion"},
       {"prologue_epilogue_insertion", "PrologueEpilogueInsertion"},
       {"post_ra_expansion", "PostRAExpansion"},
       {"finalization", "Finalization"},
-- 
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