From ce4122358f857776fde03e875eb4913fae561aed Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Wed, 7 Oct 2015 00:42:31 +0000
Subject: [PATCH] AMDGPU: Remove inferRegClassFromUses / inferRegClassFromDefs

I'm not sure why this would be necessary, and no tests fail with
them removed. Looking at the uses is suspect as well because
the use reg classes will likely change when the users are moved
as a result of moving this instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249493 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/AMDGPU/SIFixSGPRCopies.cpp | 70 ---------------------------
 1 file changed, 70 deletions(-)

diff --git a/lib/Target/AMDGPU/SIFixSGPRCopies.cpp b/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
index 448cf91e3c2..8aa6abf7ca7 100644
--- a/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
+++ b/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
@@ -85,14 +85,6 @@ class SIFixSGPRCopies : public MachineFunctionPass {
 
 private:
   static char ID;
-  const TargetRegisterClass *inferRegClassFromUses(const SIRegisterInfo *TRI,
-                                           const MachineRegisterInfo &MRI,
-                                           unsigned Reg,
-                                           unsigned SubReg) const;
-  const TargetRegisterClass *inferRegClassFromDef(const SIRegisterInfo *TRI,
-                                                 const MachineRegisterInfo &MRI,
-                                                 unsigned Reg,
-                                                 unsigned SubReg) const;
   bool isVGPRToSGPRCopy(const MachineInstr &Copy, const SIRegisterInfo *TRI,
                         const MachineRegisterInfo &MRI) const;
 
@@ -132,53 +124,6 @@ static bool hasVGPROperands(const MachineInstr &MI, const SIRegisterInfo *TRI) {
   return false;
 }
 
-/// This functions walks the use list of Reg until it finds an Instruction
-/// that isn't a COPY returns the register class of that instruction.
-/// \return The register defined by the first non-COPY instruction.
-const TargetRegisterClass *SIFixSGPRCopies::inferRegClassFromUses(
-                                                 const SIRegisterInfo *TRI,
-                                                 const MachineRegisterInfo &MRI,
-                                                 unsigned Reg,
-                                                 unsigned SubReg) const {
-
-  const TargetRegisterClass *RC
-    = TargetRegisterInfo::isVirtualRegister(Reg) ?
-    MRI.getRegClass(Reg) :
-    TRI->getPhysRegClass(Reg);
-
-  RC = TRI->getSubRegClass(RC, SubReg);
-  for (MachineRegisterInfo::use_instr_iterator
-       I = MRI.use_instr_begin(Reg), E = MRI.use_instr_end(); I != E; ++I) {
-    switch (I->getOpcode()) {
-    case AMDGPU::COPY:
-      RC = TRI->getCommonSubClass(RC, inferRegClassFromUses(TRI, MRI,
-                                  I->getOperand(0).getReg(),
-                                  I->getOperand(0).getSubReg()));
-      break;
-    }
-  }
-
-  return RC;
-}
-
-const TargetRegisterClass *SIFixSGPRCopies::inferRegClassFromDef(
-                                                 const SIRegisterInfo *TRI,
-                                                 const MachineRegisterInfo &MRI,
-                                                 unsigned Reg,
-                                                 unsigned SubReg) const {
-  if (!TargetRegisterInfo::isVirtualRegister(Reg)) {
-    const TargetRegisterClass *RC = TRI->getPhysRegClass(Reg);
-    return TRI->getSubRegClass(RC, SubReg);
-  }
-  MachineInstr *Def = MRI.getVRegDef(Reg);
-  if (Def->getOpcode() != AMDGPU::COPY) {
-    return TRI->getSubRegClass(MRI.getRegClass(Reg), SubReg);
-  }
-
-  return inferRegClassFromDef(TRI, MRI, Def->getOperand(1).getReg(),
-                                   Def->getOperand(1).getSubReg());
-}
-
 bool SIFixSGPRCopies::isVGPRToSGPRCopy(const MachineInstr &Copy,
                                       const SIRegisterInfo *TRI,
                                       const MachineRegisterInfo &MRI) const {
@@ -229,22 +174,7 @@ bool SIFixSGPRCopies::runOnMachineFunction(MachineFunction &MF) {
       }
       case AMDGPU::PHI: {
         DEBUG(dbgs() << "Fixing PHI: " << MI);
-
-        for (unsigned i = 1; i < MI.getNumOperands(); i += 2) {
-          const MachineOperand &Op = MI.getOperand(i);
-          unsigned Reg = Op.getReg();
-          const TargetRegisterClass *RC
-            = inferRegClassFromDef(TRI, MRI, Reg, Op.getSubReg());
-
-          MRI.constrainRegClass(Op.getReg(), RC);
-        }
         unsigned Reg = MI.getOperand(0).getReg();
-        const TargetRegisterClass *RC = inferRegClassFromUses(TRI, MRI, Reg,
-                                                  MI.getOperand(0).getSubReg());
-        if (TRI->getCommonSubClass(RC, &AMDGPU::VGPR_32RegClass)) {
-          MRI.constrainRegClass(Reg, &AMDGPU::VGPR_32RegClass);
-        }
-
         if (!TRI->isSGPRClass(MRI.getRegClass(Reg)))
           break;
 
-- 
2.34.1