From ff56d1a2011f239e114267c13302ea26db4f8046 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Fri, 5 Apr 2013 23:29:01 +0000 Subject: [PATCH] Enable early if conversion on PPC On cores for which we know the misprediction penalty, and we have the isel instruction, we can profitably perform early if conversion. This enables us to replace some small branch sequences with selects and avoid the potential stalls from mispredicting the branches. Enabling this feature required implementing canInsertSelect and insertSelect in PPCInstrInfo; isel code in PPCISelLowering was refactored to use these functions as well. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178926 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/PowerPC/PPCISelLowering.cpp | 29 ++------ lib/Target/PowerPC/PPCISelLowering.h | 2 + lib/Target/PowerPC/PPCInstrInfo.cpp | 99 +++++++++++++++++++++++++ lib/Target/PowerPC/PPCInstrInfo.h | 11 +++ lib/Target/PowerPC/PPCTargetMachine.cpp | 14 ++++ test/CodeGen/PowerPC/ifcvt.ll | 34 +++++++++ 6 files changed, 167 insertions(+), 22 deletions(-) create mode 100644 test/CodeGen/PowerPC/ifcvt.ll diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp index 16fc8a0e372..cec0b8f3c7c 100644 --- a/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/lib/Target/PowerPC/PPCISelLowering.cpp @@ -71,6 +71,7 @@ PPCTargetLowering::PPCTargetLowering(PPCTargetMachine &TM) : TargetLowering(TM, CreateTLOF(TM)), PPCSubTarget(*TM.getSubtargetImpl()) { const PPCSubtarget *Subtarget = &TM.getSubtarget(); PPCRegInfo = TM.getRegisterInfo(); + PPCII = TM.getInstrInfo(); setPow2DivIsCheap(); @@ -6239,29 +6240,13 @@ PPCTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI, if (PPCSubTarget.hasISEL() && (MI->getOpcode() == PPC::SELECT_CC_I4 || MI->getOpcode() == PPC::SELECT_CC_I8)) { - unsigned OpCode = MI->getOpcode() == PPC::SELECT_CC_I8 ? - PPC::ISEL8 : PPC::ISEL; - unsigned SelectPred = MI->getOperand(4).getImm(); - DebugLoc dl = MI->getDebugLoc(); + SmallVector Cond; + Cond.push_back(MI->getOperand(4)); + Cond.push_back(MI->getOperand(1)); - unsigned SubIdx; - bool SwapOps; - switch (SelectPred) { - default: llvm_unreachable("invalid predicate for isel"); - case PPC::PRED_EQ: SubIdx = PPC::sub_eq; SwapOps = false; break; - case PPC::PRED_NE: SubIdx = PPC::sub_eq; SwapOps = true; break; - case PPC::PRED_LT: SubIdx = PPC::sub_lt; SwapOps = false; break; - case PPC::PRED_GE: SubIdx = PPC::sub_lt; SwapOps = true; break; - case PPC::PRED_GT: SubIdx = PPC::sub_gt; SwapOps = false; break; - case PPC::PRED_LE: SubIdx = PPC::sub_gt; SwapOps = true; break; - case PPC::PRED_UN: SubIdx = PPC::sub_un; SwapOps = false; break; - case PPC::PRED_NU: SubIdx = PPC::sub_un; SwapOps = true; break; - } - - BuildMI(*BB, MI, dl, TII->get(OpCode), MI->getOperand(0).getReg()) - .addReg(MI->getOperand(SwapOps? 3 : 2).getReg()) - .addReg(MI->getOperand(SwapOps? 2 : 3).getReg()) - .addReg(MI->getOperand(1).getReg(), 0, SubIdx); + DebugLoc dl = MI->getDebugLoc(); + PPCII->insertSelect(*BB, MI, dl, MI->getOperand(0).getReg(), Cond, + MI->getOperand(2).getReg(), MI->getOperand(3).getReg()); } else if (MI->getOpcode() == PPC::SELECT_CC_I4 || MI->getOpcode() == PPC::SELECT_CC_I8 || MI->getOpcode() == PPC::SELECT_CC_F4 || diff --git a/lib/Target/PowerPC/PPCISelLowering.h b/lib/Target/PowerPC/PPCISelLowering.h index 7157b70d862..423e9839807 100644 --- a/lib/Target/PowerPC/PPCISelLowering.h +++ b/lib/Target/PowerPC/PPCISelLowering.h @@ -16,6 +16,7 @@ #define LLVM_TARGET_POWERPC_PPC32ISELLOWERING_H #include "PPC.h" +#include "PPCInstrInfo.h" #include "PPCRegisterInfo.h" #include "PPCSubtarget.h" #include "llvm/CodeGen/SelectionDAG.h" @@ -327,6 +328,7 @@ namespace llvm { class PPCTargetLowering : public TargetLowering { const PPCSubtarget &PPCSubTarget; const PPCRegisterInfo *PPCRegInfo; + const PPCInstrInfo *PPCII; public: explicit PPCTargetLowering(PPCTargetMachine &TM); diff --git a/lib/Target/PowerPC/PPCInstrInfo.cpp b/lib/Target/PowerPC/PPCInstrInfo.cpp index 69c54ed084b..b0dc99977c3 100644 --- a/lib/Target/PowerPC/PPCInstrInfo.cpp +++ b/lib/Target/PowerPC/PPCInstrInfo.cpp @@ -417,6 +417,105 @@ PPCInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, return 2; } +// Select analysis. +bool PPCInstrInfo::canInsertSelect(const MachineBasicBlock &MBB, + const SmallVectorImpl &Cond, + unsigned TrueReg, unsigned FalseReg, + int &CondCycles, int &TrueCycles, int &FalseCycles) const { + if (!TM.getSubtargetImpl()->hasISEL()) + return false; + + if (Cond.size() != 2) + return false; + + // If this is really a bdnz-like condition, then it cannot be turned into a + // select. + if (Cond[1].getReg() == PPC::CTR || Cond[1].getReg() == PPC::CTR8) + return false; + + // Check register classes. + const MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo(); + const TargetRegisterClass *RC = + RI.getCommonSubClass(MRI.getRegClass(TrueReg), MRI.getRegClass(FalseReg)); + if (!RC) + return false; + + // isel is for regular integer GPRs only. + if (!PPC::GPRCRegClass.hasSubClassEq(RC) && + !PPC::G8RCRegClass.hasSubClassEq(RC)) + return false; + + // FIXME: These numbers are for the A2, how well they work for other cores is + // an open question. On the A2, the isel instruction has a 2-cycle latency + // but single-cycle throughput. These numbers are used in combination with + // the MispredictPenalty setting from the active SchedMachineModel. + CondCycles = 1; + TrueCycles = 1; + FalseCycles = 1; + + return true; +} + +void PPCInstrInfo::insertSelect(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MI, DebugLoc dl, + unsigned DestReg, + const SmallVectorImpl &Cond, + unsigned TrueReg, unsigned FalseReg) const { + assert(Cond.size() == 2 && + "PPC branch conditions have two components!"); + + assert(TM.getSubtargetImpl()->hasISEL() && + "Cannot insert select on target without ISEL support"); + + // Get the register classes. + MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo(); + const TargetRegisterClass *RC = + RI.getCommonSubClass(MRI.getRegClass(TrueReg), MRI.getRegClass(FalseReg)); + assert(RC && "TrueReg and FalseReg must have overlapping register classes"); + assert((PPC::GPRCRegClass.hasSubClassEq(RC) || + PPC::G8RCRegClass.hasSubClassEq(RC)) && + "isel is for regular integer GPRs only"); + + unsigned OpCode = + PPC::GPRCRegClass.hasSubClassEq(RC) ? PPC::ISEL : PPC::ISEL8; + unsigned SelectPred = Cond[0].getImm(); + + unsigned SubIdx; + bool SwapOps; + switch (SelectPred) { + default: llvm_unreachable("invalid predicate for isel"); + case PPC::PRED_EQ: SubIdx = PPC::sub_eq; SwapOps = false; break; + case PPC::PRED_NE: SubIdx = PPC::sub_eq; SwapOps = true; break; + case PPC::PRED_LT: SubIdx = PPC::sub_lt; SwapOps = false; break; + case PPC::PRED_GE: SubIdx = PPC::sub_lt; SwapOps = true; break; + case PPC::PRED_GT: SubIdx = PPC::sub_gt; SwapOps = false; break; + case PPC::PRED_LE: SubIdx = PPC::sub_gt; SwapOps = true; break; + case PPC::PRED_UN: SubIdx = PPC::sub_un; SwapOps = false; break; + case PPC::PRED_NU: SubIdx = PPC::sub_un; SwapOps = true; break; + } + + unsigned FirstReg = SwapOps ? FalseReg : TrueReg, + SecondReg = SwapOps ? TrueReg : FalseReg; + + // The first input register of isel cannot be r0. If it is a member + // of a register class that can be r0, then copy it first (the + // register allocator should eliminate the copy). + if (MRI.getRegClass(FirstReg)->contains(PPC::R0) || + MRI.getRegClass(FirstReg)->contains(PPC::X0)) { + const TargetRegisterClass *FirstRC = + MRI.getRegClass(FirstReg)->contains(PPC::X0) ? + &PPC::G8RC_NOX0RegClass : &PPC::GPRC_NOR0RegClass; + unsigned OldFirstReg = FirstReg; + FirstReg = MRI.createVirtualRegister(FirstRC); + BuildMI(MBB, MI, dl, get(TargetOpcode::COPY), FirstReg) + .addReg(OldFirstReg); + } + + BuildMI(MBB, MI, dl, get(OpCode), DestReg) + .addReg(FirstReg).addReg(SecondReg) + .addReg(Cond[1].getReg(), 0, SubIdx); +} + void PPCInstrInfo::copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I, DebugLoc DL, unsigned DestReg, unsigned SrcReg, diff --git a/lib/Target/PowerPC/PPCInstrInfo.h b/lib/Target/PowerPC/PPCInstrInfo.h index 635e3480b06..b851216ebce 100644 --- a/lib/Target/PowerPC/PPCInstrInfo.h +++ b/lib/Target/PowerPC/PPCInstrInfo.h @@ -120,6 +120,17 @@ public: MachineBasicBlock *FBB, const SmallVectorImpl &Cond, DebugLoc DL) const; + + // Select analysis. + virtual bool canInsertSelect(const MachineBasicBlock&, + const SmallVectorImpl &Cond, + unsigned, unsigned, int&, int&, int&) const; + virtual void insertSelect(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MI, DebugLoc DL, + unsigned DstReg, + const SmallVectorImpl &Cond, + unsigned TrueReg, unsigned FalseReg) const; + virtual void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I, DebugLoc DL, unsigned DestReg, unsigned SrcReg, diff --git a/lib/Target/PowerPC/PPCTargetMachine.cpp b/lib/Target/PowerPC/PPCTargetMachine.cpp index fe851c1b6fb..59c82f6cc99 100644 --- a/lib/Target/PowerPC/PPCTargetMachine.cpp +++ b/lib/Target/PowerPC/PPCTargetMachine.cpp @@ -86,7 +86,12 @@ public: return getTM(); } + const PPCSubtarget &getPPCSubtarget() const { + return *getPPCTargetMachine().getSubtargetImpl(); + } + virtual bool addPreRegAlloc(); + virtual bool addILPOpts(); virtual bool addInstSelector(); virtual bool addPreEmitPass(); }; @@ -103,6 +108,15 @@ bool PPCPassConfig::addPreRegAlloc() { return false; } +bool PPCPassConfig::addILPOpts() { + if (getPPCSubtarget().hasISEL()) { + addPass(&EarlyIfConverterID); + return true; + } + + return false; +} + bool PPCPassConfig::addInstSelector() { // Install an instruction selector. addPass(createPPCISelDag(getPPCTargetMachine())); diff --git a/test/CodeGen/PowerPC/ifcvt.ll b/test/CodeGen/PowerPC/ifcvt.ll new file mode 100644 index 00000000000..9c966c95b72 --- /dev/null +++ b/test/CodeGen/PowerPC/ifcvt.ll @@ -0,0 +1,34 @@ +; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -verify-machineinstrs | FileCheck %s +target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64" +target triple = "powerpc64-unknown-linux-gnu" + +define i32 @test(i32 %a, i32 %b, i32 %c, i32 %d) { +entry: + %sext82 = shl i32 %d, 16 + %conv29 = ashr exact i32 %sext82, 16 + %cmp = icmp slt i32 %sext82, 0 + br i1 %cmp, label %cond.true, label %cond.false + +cond.true: ; preds = %sw.epilog + %and33 = and i32 %conv29, 32767 + %sub34 = sub nsw i32 %a, %and33 + br label %cond.end + +cond.false: ; preds = %sw.epilog + %add37 = add nsw i32 %conv29, %a + br label %cond.end + +; CHECK: @test +; CHECK: add [[REG:[0-9]+]], +; CHECK: subf [[REG2:[0-9]+]], +; CHECK: isel {{[0-9]+}}, [[REG]], [[REG2]], + +cond.end: ; preds = %cond.false, %cond.true + %cond = phi i32 [ %sub34, %cond.true ], [ %add37, %cond.false ] + %sext83 = shl i32 %cond, 16 + %conv39 = ashr exact i32 %sext83, 16 + %add41 = sub i32 %b, %a + %sub43 = add i32 %add41, %conv39 + ret i32 %sub43 +} + -- 2.34.1