AMDGPU: Optimize VOP2 operand legalization

Don't use commuteInstruction, and don't commute if
doing so will not improve legality. Skip the more
complex checks for literal operands and constant bus restrictions,
which are not a concern for VOP2 instructions because src1
does not accept SGPRs or constants and few implicitly
read vcc.

This gets called quite a few times and the
attempts at commuting are a significant fraction
of the time spent in SIFixSGPRCopies, so it's
somewhat worthwhile to optimize. With this patch and others
leading up to it, this reduces the compile time of SIFixSGPRCopies
on some of the LuxMark 2 kernels from ~8ms to ~5ms on my system.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254452 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AMDGPU/SIInstrInfo.cpp b/lib/Target/AMDGPU/SIInstrInfo.cpp
index e1668649139d2c07d03b285e986ddf96f3f0803d..a3a2d8c01eb570a256d7e136c0e5f18f4a23d46d 100644 (file)
--- a/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -871,20 +871,26 @@ MachineInstr *SIInstrInfo::commuteInstructionImpl(MachineInstr *MI,
 
   MachineOperand &Src1 = MI->getOperand(Src1Idx);
 
 
   MachineOperand &Src1 = MI->getOperand(Src1Idx);
 

-  // Make sure it's legal to commute operands for VOP2.
-  if (isVOP2(*MI) &&
-      (!isOperandLegal(MI, Src0Idx, &Src1) ||
-       !isOperandLegal(MI, Src1Idx, &Src0))) {
-    return nullptr;
+
+  if (isVOP2(*MI)) {
+    const MCInstrDesc &InstrDesc = MI->getDesc();
+    // For VOP2 instructions, any operand type is valid to use for src0.  Make
+    // sure we can use the src1 as src0.
+    //
+    // We could be stricter here and only allow commuting if there is a reason
+    // to do so. i.e. if both operands are VGPRs there is no real benefit,
+    // although MachineCSE attempts to find matches by commuting.
+    const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
+    if (!isLegalRegOperand(MRI, InstrDesc.OpInfo[Src1Idx], Src0))
+      return nullptr;

   }
 
   if (!Src1.isReg()) {
     // Allow commuting instructions with Imm operands.
     if (NewMI || !Src1.isImm() ||
   }
 
   if (!Src1.isReg()) {
     // Allow commuting instructions with Imm operands.
     if (NewMI || !Src1.isImm() ||

-       (!isVOP2(*MI) && !isVOP3(*MI))) {
+        (!isVOP2(*MI) && !isVOP3(*MI))) {

       return nullptr;
     }
       return nullptr;
     }

-

     // Be sure to copy the source modifiers to the right place.
     if (MachineOperand *Src0Mods
           = getNamedOperand(*MI, AMDGPU::OpName::src0_modifiers)) {
     // Be sure to copy the source modifiers to the right place.
     if (MachineOperand *Src0Mods
           = getNamedOperand(*MI, AMDGPU::OpName::src0_modifiers)) {


@@ -1720,6 +1726,41 @@ void SIInstrInfo::swapOperands(MachineBasicBlock::iterator Inst) const {
   Inst->addOperand(Op1);
 }
 
   Inst->addOperand(Op1);
 }
 

+bool SIInstrInfo::isLegalRegOperand(const MachineRegisterInfo &MRI,
+                                    const MCOperandInfo &OpInfo,
+                                    const MachineOperand &MO) const {
+  if (!MO.isReg())
+    return false;
+
+  unsigned Reg = MO.getReg();
+  const TargetRegisterClass *RC =
+    TargetRegisterInfo::isVirtualRegister(Reg) ?
+    MRI.getRegClass(Reg) :
+    RI.getPhysRegClass(Reg);
+
+  // In order to be legal, the common sub-class must be equal to the
+  // class of the current operand.  For example:
+  //
+  // v_mov_b32 s0 ; Operand defined as vsrc_32
+  //              ; RI.getCommonSubClass(s0,vsrc_32) = sgpr ; LEGAL
+  //
+  // s_sendmsg 0, s0 ; Operand defined as m0reg
+  //                 ; RI.getCommonSubClass(s0,m0reg) = m0reg ; NOT LEGAL
+
+  return RI.getCommonSubClass(RC, RI.getRegClass(OpInfo.RegClass)) == RC;
+}
+
+bool SIInstrInfo::isLegalVSrcOperand(const MachineRegisterInfo &MRI,
+                                     const MCOperandInfo &OpInfo,
+                                     const MachineOperand &MO) const {
+  if (MO.isReg())
+    return isLegalRegOperand(MRI, OpInfo, MO);
+
+  // Handle non-register types that are treated like immediates.
+  assert(MO.isImm() || MO.isTargetIndex() || MO.isFI());
+  return true;
+}
+

 bool SIInstrInfo::isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
                                  const MachineOperand *MO) const {
   const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
 bool SIInstrInfo::isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
                                  const MachineOperand *MO) const {
   const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();


@@ -1747,21 +1788,7 @@ bool SIInstrInfo::isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
 
   if (MO->isReg()) {
     assert(DefinedRC);
 
   if (MO->isReg()) {
     assert(DefinedRC);

-    const TargetRegisterClass *RC =
-        TargetRegisterInfo::isVirtualRegister(MO->getReg()) ?
-            MRI.getRegClass(MO->getReg()) :
-            RI.getPhysRegClass(MO->getReg());
-
-    // In order to be legal, the common sub-class must be equal to the
-    // class of the current operand.  For example:
-    //
-    // v_mov_b32 s0 ; Operand defined as vsrc_32
-    //              ; RI.getCommonSubClass(s0,vsrc_32) = sgpr ; LEGAL
-    //
-    // s_sendmsg 0, s0 ; Operand defined as m0reg
-    //                 ; RI.getCommonSubClass(s0,m0reg) = m0reg ; NOT LEGAL
-
-    return RI.getCommonSubClass(RC, RI.getRegClass(OpInfo.RegClass)) == RC;
+    return isLegalRegOperand(MRI, OpInfo, *MO);

   }
 
 
   }
 
 


@@ -1776,6 +1803,81 @@ bool SIInstrInfo::isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
   return isImmOperandLegal(MI, OpIdx, *MO);
 }
 
   return isImmOperandLegal(MI, OpIdx, *MO);
 }
 

+void SIInstrInfo::legalizeOperandsVOP2(MachineRegisterInfo &MRI,
+                                       MachineInstr *MI) const {
+  unsigned Opc = MI->getOpcode();
+  const MCInstrDesc &InstrDesc = get(Opc);
+
+  int Src1Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1);
+  MachineOperand &Src1 = MI->getOperand(Src1Idx);
+
+  // If there is an implicit SGPR use such as VCC use for v_addc_u32/v_subb_u32
+  // we need to only have one constant bus use.
+  //
+  // Note we do not need to worry about literal constants here. They are
+  // disabled for the operand type for instructions because they will always
+  // violate the one constant bus use rule.
+  bool HasImplicitSGPR = findImplicitSGPRRead(*MI) != AMDGPU::NoRegister;
+  if (HasImplicitSGPR) {
+    int Src0Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src0);
+    MachineOperand &Src0 = MI->getOperand(Src0Idx);
+
+    if (Src0.isReg() && RI.isSGPRReg(MRI, Src0.getReg()))
+      legalizeOpWithMove(MI, Src0Idx);
+  }
+
+  // VOP2 src0 instructions support all operand types, so we don't need to check
+  // their legality. If src1 is already legal, we don't need to do anything.
+  if (isLegalRegOperand(MRI, InstrDesc.OpInfo[Src1Idx], Src1))
+    return;
+
+  // We do not use commuteInstruction here because it is too aggressive and will
+  // commute if it is possible. We only want to commute here if it improves
+  // legality. This can be called a fairly large number of times so don't waste
+  // compile time pointlessly swapping and checking legality again.
+  if (HasImplicitSGPR || !MI->isCommutable()) {
+    legalizeOpWithMove(MI, Src1Idx);
+    return;
+  }
+
+  int Src0Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src0);
+  MachineOperand &Src0 = MI->getOperand(Src0Idx);
+
+  // If src0 can be used as src1, commuting will make the operands legal.
+  // Otherwise we have to give up and insert a move.
+  //
+  // TODO: Other immediate-like operand kinds could be commuted if there was a
+  // MachineOperand::ChangeTo* for them.
+  if ((!Src1.isImm() && !Src1.isReg()) ||
+      !isLegalRegOperand(MRI, InstrDesc.OpInfo[Src1Idx], Src0)) {
+    legalizeOpWithMove(MI, Src1Idx);
+    return;
+  }
+
+  int CommutedOpc = commuteOpcode(*MI);
+  if (CommutedOpc == -1) {
+    legalizeOpWithMove(MI, Src1Idx);
+    return;
+  }
+
+  MI->setDesc(get(CommutedOpc));
+
+  unsigned Src0Reg = Src0.getReg();
+  unsigned Src0SubReg = Src0.getSubReg();
+  bool Src0Kill = Src0.isKill();
+
+  if (Src1.isImm())
+    Src0.ChangeToImmediate(Src1.getImm());
+  else if (Src1.isReg()) {
+    Src0.ChangeToRegister(Src1.getReg(), false, false, Src1.isKill());
+    Src0.setSubReg(Src1.getSubReg());
+  } else
+    llvm_unreachable("Should only have register or immediate operands");
+
+  Src1.ChangeToRegister(Src0Reg, false, false, Src0Kill);
+  Src1.setSubReg(Src0SubReg);
+}
+

 // Legalize VOP3 operands. Because all operand types are supported for any
 // operand, and since literal constants are not allowed and should never be
 // seen, we only need to worry about inserting copies if we use multiple SGPR
 // Legalize VOP3 operands. Because all operand types are supported for any
 // operand, and since literal constants are not allowed and should never be
 // seen, we only need to worry about inserting copies if we use multiple SGPR


@@ -1821,32 +1923,10 @@ void SIInstrInfo::legalizeOperandsVOP3(
 
 void SIInstrInfo::legalizeOperands(MachineInstr *MI) const {
   MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
 
 void SIInstrInfo::legalizeOperands(MachineInstr *MI) const {
   MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();

-  unsigned Opc = MI->getOpcode();

 
   // Legalize VOP2
   if (isVOP2(*MI)) {
 
   // Legalize VOP2
   if (isVOP2(*MI)) {

-    int Src0Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src0);
-    int Src1Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1);
-
-    // Legalize src0
-    if (!isOperandLegal(MI, Src0Idx))
-      legalizeOpWithMove(MI, Src0Idx);
-
-    // Legalize src1
-    if (isOperandLegal(MI, Src1Idx))
-      return;
-
-    // Usually src0 of VOP2 instructions allow more types of inputs
-    // than src1, so try to commute the instruction to decrease our
-    // chances of having to insert a MOV instruction to legalize src1.
-    if (MI->isCommutable()) {
-      if (commuteInstruction(MI))
-        // If we are successful in commuting, then we know MI is legal, so
-        // we are done.
-        return;
-    }
-
-    legalizeOpWithMove(MI, Src1Idx);
+    legalizeOperandsVOP2(MRI, MI);

     return;
   }
 
     return;
   }
 

diff --git a/lib/Target/AMDGPU/SIInstrInfo.h b/lib/Target/AMDGPU/SIInstrInfo.h
index 2bce87f3bd06f5b813fe1056d6d400abb6e9fe70..8d18d29196f7f685dc47b3cf48fa054bc421bb76 100644 (file)
--- a/lib/Target/AMDGPU/SIInstrInfo.h
+++ b/lib/Target/AMDGPU/SIInstrInfo.h
@@ -381,6 +381,23 @@ public:
   bool isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
                       const MachineOperand *MO = nullptr) const;
 
   bool isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
                       const MachineOperand *MO = nullptr) const;
 

+  /// \brief Check if \p MO would be a valid operand for the given operand
+  /// definition \p OpInfo. Note this does not attempt to validate constant bus
+  /// restrictions (e.g. literal constant usage).
+  bool isLegalVSrcOperand(const MachineRegisterInfo &MRI,
+                          const MCOperandInfo &OpInfo,
+                          const MachineOperand &MO) const;
+
+  /// \brief Check if \p MO (a register operand) is a legal register for the
+  /// given operand description.
+  bool isLegalRegOperand(const MachineRegisterInfo &MRI,
+                         const MCOperandInfo &OpInfo,
+                         const MachineOperand &MO) const;
+
+  /// \brief Legalize operands in \p MI by either commuting it or inserting a
+  /// copy of src1.
+  void legalizeOperandsVOP2(MachineRegisterInfo &MRI, MachineInstr *MI) const;
+

   /// \brief Fix operands in \p MI to satisfy constant bus requirements.
   void legalizeOperandsVOP3(MachineRegisterInfo &MRI, MachineInstr *MI) const;
 
   /// \brief Fix operands in \p MI to satisfy constant bus requirements.
   void legalizeOperandsVOP3(MachineRegisterInfo &MRI, MachineInstr *MI) const;
 

diff --git a/lib/Target/AMDGPU/SIRegisterInfo.h b/lib/Target/AMDGPU/SIRegisterInfo.h
index eafe4053e8789c5bb1de61805410900d7d812c3a..1795237c214016fff53d2cb781fcef1a20512122 100644 (file)
--- a/lib/Target/AMDGPU/SIRegisterInfo.h
+++ b/lib/Target/AMDGPU/SIRegisterInfo.h
@@ -18,6 +18,7 @@
 
 #include "AMDGPURegisterInfo.h"
 #include "AMDGPUSubtarget.h"
 
 #include "AMDGPURegisterInfo.h"
 #include "AMDGPUSubtarget.h"

+#include "llvm/CodeGen/MachineRegisterInfo.h"

 #include "llvm/Support/Debug.h"
 
 namespace llvm {
 #include "llvm/Support/Debug.h"
 
 namespace llvm {


@@ -65,6 +66,12 @@ public:
     return isSGPRClass(getRegClass(RCID));
   }
 
     return isSGPRClass(getRegClass(RCID));
   }
 

+  bool isSGPRReg(const MachineRegisterInfo &MRI, unsigned Reg) const {
+    if (TargetRegisterInfo::isVirtualRegister(Reg))
+      return isSGPRClass(MRI.getRegClass(Reg));
+    return getPhysRegClass(Reg);
+  }
+

   /// \returns true if this class contains VGPR registers.
   bool hasVGPRs(const TargetRegisterClass *RC) const;
 
   /// \returns true if this class contains VGPR registers.
   bool hasVGPRs(const TargetRegisterClass *RC) const;