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-rw-r--r--llvm/lib/Target/ARM/MVEVPTBlockPass.cpp278
1 files changed, 278 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/MVEVPTBlockPass.cpp b/llvm/lib/Target/ARM/MVEVPTBlockPass.cpp
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+++ b/llvm/lib/Target/ARM/MVEVPTBlockPass.cpp
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+//===-- MVEVPTBlockPass.cpp - Insert MVE VPT blocks -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARM.h"
+#include "ARMMachineFunctionInfo.h"
+#include "ARMSubtarget.h"
+#include "MCTargetDesc/ARMBaseInfo.h"
+#include "Thumb2InstrInfo.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineInstrBundle.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/IR/DebugLoc.h"
+#include "llvm/MC/MCInstrDesc.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+#include <cassert>
+#include <new>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "arm-mve-vpt"
+
+namespace {
+ class MVEVPTBlock : public MachineFunctionPass {
+ public:
+ static char ID;
+ const Thumb2InstrInfo *TII;
+ const TargetRegisterInfo *TRI;
+
+ MVEVPTBlock() : MachineFunctionPass(ID) {}
+
+ bool runOnMachineFunction(MachineFunction &Fn) override;
+
+ MachineFunctionProperties getRequiredProperties() const override {
+ return MachineFunctionProperties().set(
+ MachineFunctionProperties::Property::NoVRegs);
+ }
+
+ StringRef getPassName() const override {
+ return "MVE VPT block insertion pass";
+ }
+
+ private:
+ bool InsertVPTBlocks(MachineBasicBlock &MBB);
+ };
+
+ char MVEVPTBlock::ID = 0;
+
+} // end anonymous namespace
+
+INITIALIZE_PASS(MVEVPTBlock, DEBUG_TYPE, "ARM MVE VPT block pass", false, false)
+
+enum VPTMaskValue {
+ T = 8, // 0b1000
+ TT = 4, // 0b0100
+ TE = 12, // 0b1100
+ TTT = 2, // 0b0010
+ TTE = 6, // 0b0110
+ TEE = 10, // 0b1010
+ TET = 14, // 0b1110
+ TTTT = 1, // 0b0001
+ TTTE = 3, // 0b0011
+ TTEE = 5, // 0b0101
+ TTET = 7, // 0b0111
+ TEEE = 9, // 0b1001
+ TEET = 11, // 0b1011
+ TETT = 13, // 0b1101
+ TETE = 15 // 0b1111
+};
+
+static unsigned VCMPOpcodeToVPT(unsigned Opcode) {
+ switch (Opcode) {
+ case ARM::MVE_VCMPf32:
+ return ARM::MVE_VPTv4f32;
+ case ARM::MVE_VCMPf16:
+ return ARM::MVE_VPTv8f16;
+ case ARM::MVE_VCMPi8:
+ return ARM::MVE_VPTv16i8;
+ case ARM::MVE_VCMPi16:
+ return ARM::MVE_VPTv8i16;
+ case ARM::MVE_VCMPi32:
+ return ARM::MVE_VPTv4i32;
+ case ARM::MVE_VCMPu8:
+ return ARM::MVE_VPTv16u8;
+ case ARM::MVE_VCMPu16:
+ return ARM::MVE_VPTv8u16;
+ case ARM::MVE_VCMPu32:
+ return ARM::MVE_VPTv4u32;
+ case ARM::MVE_VCMPs8:
+ return ARM::MVE_VPTv16s8;
+ case ARM::MVE_VCMPs16:
+ return ARM::MVE_VPTv8s16;
+ case ARM::MVE_VCMPs32:
+ return ARM::MVE_VPTv4s32;
+
+ case ARM::MVE_VCMPf32r:
+ return ARM::MVE_VPTv4f32r;
+ case ARM::MVE_VCMPf16r:
+ return ARM::MVE_VPTv8f16r;
+ case ARM::MVE_VCMPi8r:
+ return ARM::MVE_VPTv16i8r;
+ case ARM::MVE_VCMPi16r:
+ return ARM::MVE_VPTv8i16r;
+ case ARM::MVE_VCMPi32r:
+ return ARM::MVE_VPTv4i32r;
+ case ARM::MVE_VCMPu8r:
+ return ARM::MVE_VPTv16u8r;
+ case ARM::MVE_VCMPu16r:
+ return ARM::MVE_VPTv8u16r;
+ case ARM::MVE_VCMPu32r:
+ return ARM::MVE_VPTv4u32r;
+ case ARM::MVE_VCMPs8r:
+ return ARM::MVE_VPTv16s8r;
+ case ARM::MVE_VCMPs16r:
+ return ARM::MVE_VPTv8s16r;
+ case ARM::MVE_VCMPs32r:
+ return ARM::MVE_VPTv4s32r;
+
+ default:
+ return 0;
+ }
+}
+
+static MachineInstr *findVCMPToFoldIntoVPST(MachineBasicBlock::iterator MI,
+ const TargetRegisterInfo *TRI,
+ unsigned &NewOpcode) {
+ // Search backwards to the instruction that defines VPR. This may or not
+ // be a VCMP, we check that after this loop. If we find another instruction
+ // that reads cpsr, we return nullptr.
+ MachineBasicBlock::iterator CmpMI = MI;
+ while (CmpMI != MI->getParent()->begin()) {
+ --CmpMI;
+ if (CmpMI->modifiesRegister(ARM::VPR, TRI))
+ break;
+ if (CmpMI->readsRegister(ARM::VPR, TRI))
+ break;
+ }
+
+ if (CmpMI == MI)
+ return nullptr;
+ NewOpcode = VCMPOpcodeToVPT(CmpMI->getOpcode());
+ if (NewOpcode == 0)
+ return nullptr;
+
+ // Search forward from CmpMI to MI, checking if either register was def'd
+ if (registerDefinedBetween(CmpMI->getOperand(1).getReg(), std::next(CmpMI),
+ MI, TRI))
+ return nullptr;
+ if (registerDefinedBetween(CmpMI->getOperand(2).getReg(), std::next(CmpMI),
+ MI, TRI))
+ return nullptr;
+ return &*CmpMI;
+}
+
+bool MVEVPTBlock::InsertVPTBlocks(MachineBasicBlock &Block) {
+ bool Modified = false;
+ MachineBasicBlock::instr_iterator MBIter = Block.instr_begin();
+ MachineBasicBlock::instr_iterator EndIter = Block.instr_end();
+
+ while (MBIter != EndIter) {
+ MachineInstr *MI = &*MBIter;
+ unsigned PredReg = 0;
+ DebugLoc dl = MI->getDebugLoc();
+
+ ARMVCC::VPTCodes Pred = getVPTInstrPredicate(*MI, PredReg);
+
+ // The idea of the predicate is that None, Then and Else are for use when
+ // handling assembly language: they correspond to the three possible
+ // suffixes "", "t" and "e" on the mnemonic. So when instructions are read
+ // from assembly source or disassembled from object code, you expect to see
+ // a mixture whenever there's a long VPT block. But in code generation, we
+ // hope we'll never generate an Else as input to this pass.
+ assert(Pred != ARMVCC::Else && "VPT block pass does not expect Else preds");
+
+ if (Pred == ARMVCC::None) {
+ ++MBIter;
+ continue;
+ }
+
+ LLVM_DEBUG(dbgs() << "VPT block created for: "; MI->dump());
+ int VPTInstCnt = 1;
+ ARMVCC::VPTCodes NextPred;
+
+ // Look at subsequent instructions, checking if they can be in the same VPT
+ // block.
+ ++MBIter;
+ while (MBIter != EndIter && VPTInstCnt < 4) {
+ NextPred = getVPTInstrPredicate(*MBIter, PredReg);
+ assert(NextPred != ARMVCC::Else &&
+ "VPT block pass does not expect Else preds");
+ if (NextPred != Pred)
+ break;
+ LLVM_DEBUG(dbgs() << " adding : "; MBIter->dump());
+ ++VPTInstCnt;
+ ++MBIter;
+ };
+
+ unsigned BlockMask = 0;
+ switch (VPTInstCnt) {
+ case 1:
+ BlockMask = VPTMaskValue::T;
+ break;
+ case 2:
+ BlockMask = VPTMaskValue::TT;
+ break;
+ case 3:
+ BlockMask = VPTMaskValue::TTT;
+ break;
+ case 4:
+ BlockMask = VPTMaskValue::TTTT;
+ break;
+ default:
+ llvm_unreachable("Unexpected number of instruction in a VPT block");
+ };
+
+ // Search back for a VCMP that can be folded to create a VPT, or else create
+ // a VPST directly
+ MachineInstrBuilder MIBuilder;
+ unsigned NewOpcode;
+ MachineInstr *VCMP = findVCMPToFoldIntoVPST(MI, TRI, NewOpcode);
+ if (VCMP) {
+ LLVM_DEBUG(dbgs() << " folding VCMP into VPST: "; VCMP->dump());
+ MIBuilder = BuildMI(Block, MI, dl, TII->get(NewOpcode));
+ MIBuilder.addImm(BlockMask);
+ MIBuilder.add(VCMP->getOperand(1));
+ MIBuilder.add(VCMP->getOperand(2));
+ MIBuilder.add(VCMP->getOperand(3));
+ VCMP->eraseFromParent();
+ } else {
+ MIBuilder = BuildMI(Block, MI, dl, TII->get(ARM::MVE_VPST));
+ MIBuilder.addImm(BlockMask);
+ }
+
+ finalizeBundle(
+ Block, MachineBasicBlock::instr_iterator(MIBuilder.getInstr()), MBIter);
+
+ Modified = true;
+ }
+ return Modified;
+}
+
+bool MVEVPTBlock::runOnMachineFunction(MachineFunction &Fn) {
+ const ARMSubtarget &STI =
+ static_cast<const ARMSubtarget &>(Fn.getSubtarget());
+
+ if (!STI.isThumb2() || !STI.hasMVEIntegerOps())
+ return false;
+
+ TII = static_cast<const Thumb2InstrInfo *>(STI.getInstrInfo());
+ TRI = STI.getRegisterInfo();
+
+ LLVM_DEBUG(dbgs() << "********** ARM MVE VPT BLOCKS **********\n"
+ << "********** Function: " << Fn.getName() << '\n');
+
+ bool Modified = false;
+ for (MachineBasicBlock &MBB : Fn)
+ Modified |= InsertVPTBlocks(MBB);
+
+ LLVM_DEBUG(dbgs() << "**************************************\n");
+ return Modified;
+}
+
+/// createMVEVPTBlock - Returns an instance of the MVE VPT block
+/// insertion pass.
+FunctionPass *llvm::createMVEVPTBlockPass() { return new MVEVPTBlock(); }
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