Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 1 | //===-- WebAssemblyPeephole.cpp - WebAssembly Peephole Optimiztions -------===// |
| 2 | // |
Chandler Carruth | 2946cd7 | 2019-01-19 08:50:56 +0000 | [diff] [blame^] | 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | /// |
| 9 | /// \file |
Adrian Prantl | 5f8f34e4 | 2018-05-01 15:54:18 +0000 | [diff] [blame] | 10 | /// Late peephole optimizations for WebAssembly. |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 11 | /// |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 14 | #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 15 | #include "WebAssembly.h" |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 16 | #include "WebAssemblyMachineFunctionInfo.h" |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 17 | #include "WebAssemblySubtarget.h" |
| 18 | #include "llvm/Analysis/TargetLibraryInfo.h" |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 19 | #include "llvm/CodeGen/MachineFunctionPass.h" |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 20 | #include "llvm/CodeGen/MachineInstrBuilder.h" |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 21 | #include "llvm/CodeGen/MachineRegisterInfo.h" |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 22 | using namespace llvm; |
| 23 | |
| 24 | #define DEBUG_TYPE "wasm-peephole" |
| 25 | |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 26 | static cl::opt<bool> DisableWebAssemblyFallthroughReturnOpt( |
| 27 | "disable-wasm-fallthrough-return-opt", cl::Hidden, |
| 28 | cl::desc("WebAssembly: Disable fallthrough-return optimizations."), |
| 29 | cl::init(false)); |
| 30 | |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 31 | namespace { |
| 32 | class WebAssemblyPeephole final : public MachineFunctionPass { |
Mehdi Amini | 117296c | 2016-10-01 02:56:57 +0000 | [diff] [blame] | 33 | StringRef getPassName() const override { |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 34 | return "WebAssembly late peephole optimizer"; |
| 35 | } |
| 36 | |
Dan Gohman | acc0941 | 2015-12-10 14:12:04 +0000 | [diff] [blame] | 37 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
| 38 | AU.setPreservesCFG(); |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 39 | AU.addRequired<TargetLibraryInfoWrapperPass>(); |
Dan Gohman | acc0941 | 2015-12-10 14:12:04 +0000 | [diff] [blame] | 40 | MachineFunctionPass::getAnalysisUsage(AU); |
| 41 | } |
| 42 | |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 43 | bool runOnMachineFunction(MachineFunction &MF) override; |
| 44 | |
| 45 | public: |
| 46 | static char ID; |
| 47 | WebAssemblyPeephole() : MachineFunctionPass(ID) {} |
| 48 | }; |
| 49 | } // end anonymous namespace |
| 50 | |
| 51 | char WebAssemblyPeephole::ID = 0; |
Jacob Gravelle | 4092645 | 2018-03-30 20:36:58 +0000 | [diff] [blame] | 52 | INITIALIZE_PASS(WebAssemblyPeephole, DEBUG_TYPE, |
| 53 | "WebAssembly peephole optimizations", false, false) |
| 54 | |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 55 | FunctionPass *llvm::createWebAssemblyPeephole() { |
| 56 | return new WebAssemblyPeephole(); |
| 57 | } |
| 58 | |
Dan Gohman | 7100809 | 2016-05-17 23:19:03 +0000 | [diff] [blame] | 59 | /// If desirable, rewrite NewReg to a drop register. |
| 60 | static bool MaybeRewriteToDrop(unsigned OldReg, unsigned NewReg, |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 61 | MachineOperand &MO, WebAssemblyFunctionInfo &MFI, |
Dan Gohman | 7100809 | 2016-05-17 23:19:03 +0000 | [diff] [blame] | 62 | MachineRegisterInfo &MRI) { |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 63 | bool Changed = false; |
Dan Gohman | 27a11eef | 2016-02-21 03:27:22 +0000 | [diff] [blame] | 64 | if (OldReg == NewReg) { |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 65 | Changed = true; |
Dan Gohman | 847afa2 | 2016-05-19 21:07:20 +0000 | [diff] [blame] | 66 | unsigned NewReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg)); |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 67 | MO.setReg(NewReg); |
| 68 | MO.setIsDead(); |
| 69 | MFI.stackifyVReg(NewReg); |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 70 | } |
| 71 | return Changed; |
| 72 | } |
| 73 | |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 74 | static bool MaybeRewriteToFallthrough(MachineInstr &MI, MachineBasicBlock &MBB, |
| 75 | const MachineFunction &MF, |
| 76 | WebAssemblyFunctionInfo &MFI, |
| 77 | MachineRegisterInfo &MRI, |
| 78 | const WebAssemblyInstrInfo &TII, |
| 79 | unsigned FallthroughOpc, |
| 80 | unsigned CopyLocalOpc) { |
| 81 | if (DisableWebAssemblyFallthroughReturnOpt) |
| 82 | return false; |
| 83 | if (&MBB != &MF.back()) |
| 84 | return false; |
Sam Clegg | cf2a9e2 | 2018-07-16 23:09:29 +0000 | [diff] [blame] | 85 | |
| 86 | MachineBasicBlock::iterator End = MBB.end(); |
| 87 | --End; |
| 88 | assert(End->getOpcode() == WebAssembly::END_FUNCTION); |
| 89 | --End; |
| 90 | if (&MI != &*End) |
| 91 | return false; |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 92 | |
Dan Gohman | b6afd20 | 2017-02-09 23:19:03 +0000 | [diff] [blame] | 93 | if (FallthroughOpc != WebAssembly::FALLTHROUGH_RETURN_VOID) { |
| 94 | // If the operand isn't stackified, insert a COPY to read the operand and |
| 95 | // stackify it. |
| 96 | MachineOperand &MO = MI.getOperand(0); |
| 97 | unsigned Reg = MO.getReg(); |
| 98 | if (!MFI.isVRegStackified(Reg)) { |
| 99 | unsigned NewReg = MRI.createVirtualRegister(MRI.getRegClass(Reg)); |
| 100 | BuildMI(MBB, MI, MI.getDebugLoc(), TII.get(CopyLocalOpc), NewReg) |
| 101 | .addReg(Reg); |
| 102 | MO.setReg(NewReg); |
| 103 | MFI.stackifyVReg(NewReg); |
| 104 | } |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 105 | } |
| 106 | |
| 107 | // Rewrite the return. |
| 108 | MI.setDesc(TII.get(FallthroughOpc)); |
| 109 | return true; |
| 110 | } |
| 111 | |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 112 | bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) { |
Nicola Zaghen | d34e60c | 2018-05-14 12:53:11 +0000 | [diff] [blame] | 113 | LLVM_DEBUG({ |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 114 | dbgs() << "********** Peephole **********\n" |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 115 | << "********** Function: " << MF.getName() << '\n'; |
| 116 | }); |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 117 | |
| 118 | MachineRegisterInfo &MRI = MF.getRegInfo(); |
| 119 | WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>(); |
Derek Schuff | 5629ec1 | 2016-08-02 23:31:56 +0000 | [diff] [blame] | 120 | const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo(); |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 121 | const WebAssemblyTargetLowering &TLI = |
| 122 | *MF.getSubtarget<WebAssemblySubtarget>().getTargetLowering(); |
| 123 | auto &LibInfo = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); |
| 124 | bool Changed = false; |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 125 | |
| 126 | for (auto &MBB : MF) |
| 127 | for (auto &MI : MBB) |
| 128 | switch (MI.getOpcode()) { |
| 129 | default: |
| 130 | break; |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 131 | case WebAssembly::CALL_I32: |
| 132 | case WebAssembly::CALL_I64: { |
| 133 | MachineOperand &Op1 = MI.getOperand(1); |
| 134 | if (Op1.isSymbol()) { |
| 135 | StringRef Name(Op1.getSymbolName()); |
| 136 | if (Name == TLI.getLibcallName(RTLIB::MEMCPY) || |
| 137 | Name == TLI.getLibcallName(RTLIB::MEMMOVE) || |
| 138 | Name == TLI.getLibcallName(RTLIB::MEMSET)) { |
Derek Schuff | 4b320b7 | 2017-01-24 00:01:18 +0000 | [diff] [blame] | 139 | LibFunc Func; |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 140 | if (LibInfo.getLibFunc(Name, Func)) { |
JF Bastien | 1a6c760 | 2016-01-26 20:22:42 +0000 | [diff] [blame] | 141 | const auto &Op2 = MI.getOperand(2); |
Derek Schuff | e7305cc | 2016-01-26 21:08:27 +0000 | [diff] [blame] | 142 | if (!Op2.isReg()) |
JF Bastien | 1a6c760 | 2016-01-26 20:22:42 +0000 | [diff] [blame] | 143 | report_fatal_error("Peephole: call to builtin function with " |
Derek Schuff | e7305cc | 2016-01-26 21:08:27 +0000 | [diff] [blame] | 144 | "wrong signature, not consuming reg"); |
| 145 | MachineOperand &MO = MI.getOperand(0); |
| 146 | unsigned OldReg = MO.getReg(); |
| 147 | unsigned NewReg = Op2.getReg(); |
Derek Schuff | 90d9e8d | 2016-01-26 22:47:43 +0000 | [diff] [blame] | 148 | |
Dan Gohman | 847afa2 | 2016-05-19 21:07:20 +0000 | [diff] [blame] | 149 | if (MRI.getRegClass(NewReg) != MRI.getRegClass(OldReg)) |
Derek Schuff | e7305cc | 2016-01-26 21:08:27 +0000 | [diff] [blame] | 150 | report_fatal_error("Peephole: call to builtin function with " |
| 151 | "wrong signature, from/to mismatch"); |
Dan Gohman | 7100809 | 2016-05-17 23:19:03 +0000 | [diff] [blame] | 152 | Changed |= MaybeRewriteToDrop(OldReg, NewReg, MO, MFI, MRI); |
Dan Gohman | bdf08d5 | 2016-01-26 04:01:11 +0000 | [diff] [blame] | 153 | } |
| 154 | } |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 155 | } |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 156 | break; |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 157 | } |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 158 | // Optimize away an explicit void return at the end of the function. |
| 159 | case WebAssembly::RETURN_I32: |
| 160 | Changed |= MaybeRewriteToFallthrough( |
| 161 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_I32, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 162 | WebAssembly::COPY_I32); |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 163 | break; |
| 164 | case WebAssembly::RETURN_I64: |
| 165 | Changed |= MaybeRewriteToFallthrough( |
| 166 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_I64, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 167 | WebAssembly::COPY_I64); |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 168 | break; |
| 169 | case WebAssembly::RETURN_F32: |
| 170 | Changed |= MaybeRewriteToFallthrough( |
| 171 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_F32, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 172 | WebAssembly::COPY_F32); |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 173 | break; |
| 174 | case WebAssembly::RETURN_F64: |
| 175 | Changed |= MaybeRewriteToFallthrough( |
| 176 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_F64, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 177 | WebAssembly::COPY_F64); |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 178 | break; |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 179 | case WebAssembly::RETURN_v16i8: |
Derek Schuff | 5629ec1 | 2016-08-02 23:31:56 +0000 | [diff] [blame] | 180 | Changed |= MaybeRewriteToFallthrough( |
| 181 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v16i8, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 182 | WebAssembly::COPY_V128); |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 183 | break; |
| 184 | case WebAssembly::RETURN_v8i16: |
Derek Schuff | 5629ec1 | 2016-08-02 23:31:56 +0000 | [diff] [blame] | 185 | Changed |= MaybeRewriteToFallthrough( |
| 186 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v8i16, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 187 | WebAssembly::COPY_V128); |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 188 | break; |
| 189 | case WebAssembly::RETURN_v4i32: |
Derek Schuff | 5629ec1 | 2016-08-02 23:31:56 +0000 | [diff] [blame] | 190 | Changed |= MaybeRewriteToFallthrough( |
| 191 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v4i32, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 192 | WebAssembly::COPY_V128); |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 193 | break; |
Derek Schuff | 51ed131 | 2018-08-07 21:24:01 +0000 | [diff] [blame] | 194 | case WebAssembly::RETURN_v2i64: |
| 195 | Changed |= MaybeRewriteToFallthrough( |
| 196 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v2i64, |
| 197 | WebAssembly::COPY_V128); |
| 198 | break; |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 199 | case WebAssembly::RETURN_v4f32: |
Derek Schuff | 5629ec1 | 2016-08-02 23:31:56 +0000 | [diff] [blame] | 200 | Changed |= MaybeRewriteToFallthrough( |
| 201 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v4f32, |
Dan Gohman | 4fc4e42 | 2016-10-24 19:49:43 +0000 | [diff] [blame] | 202 | WebAssembly::COPY_V128); |
Derek Schuff | 39bf39f | 2016-08-02 23:16:09 +0000 | [diff] [blame] | 203 | break; |
Derek Schuff | 51ed131 | 2018-08-07 21:24:01 +0000 | [diff] [blame] | 204 | case WebAssembly::RETURN_v2f64: |
| 205 | Changed |= MaybeRewriteToFallthrough( |
| 206 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_v2f64, |
| 207 | WebAssembly::COPY_V128); |
| 208 | break; |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 209 | case WebAssembly::RETURN_VOID: |
Dan Gohman | b6afd20 | 2017-02-09 23:19:03 +0000 | [diff] [blame] | 210 | Changed |= MaybeRewriteToFallthrough( |
| 211 | MI, MBB, MF, MFI, MRI, TII, WebAssembly::FALLTHROUGH_RETURN_VOID, |
| 212 | WebAssembly::INSTRUCTION_LIST_END); |
Dan Gohman | b7c2400 | 2016-05-21 00:21:56 +0000 | [diff] [blame] | 213 | break; |
Dan Gohman | 81719f8 | 2015-11-25 16:55:01 +0000 | [diff] [blame] | 214 | } |
| 215 | |
| 216 | return Changed; |
| 217 | } |