1 //===-- VEFrameLowering.cpp - VE Frame Information ------------------------===// 2 // 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 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file contains the VE implementation of TargetFrameLowering class. 10 // 11 // On VE, stack frames are structured as follows: 12 // 13 // The stack grows downward. 14 // 15 // All of the individual frame areas on the frame below are optional, i.e. it's 16 // possible to create a function so that the particular area isn't present 17 // in the frame. 18 // 19 // At function entry, the "frame" looks as follows: 20 // 21 // | | Higher address 22 // |----------------------------------------------| 23 // | Parameter area for this function | 24 // |----------------------------------------------| 25 // | Register save area (RSA) for this function | 26 // |----------------------------------------------| 27 // | Return address for this function | 28 // |----------------------------------------------| 29 // | Frame pointer for this function | 30 // |----------------------------------------------| <- sp 31 // | | Lower address 32 // 33 // VE doesn't use on demand stack allocation, so user code generated by LLVM 34 // needs to call VEOS to allocate stack frame. VE's ABI want to reduce the 35 // number of VEOS calls, so ABI requires to allocate not only RSA (in general 36 // CSR, callee saved register) area but also call frame at the prologue of 37 // caller function. 38 // 39 // After the prologue has run, the frame has the following general structure. 40 // Note that technically the last frame area (VLAs) doesn't get created until 41 // in the main function body, after the prologue is run. However, it's depicted 42 // here for completeness. 43 // 44 // | | Higher address 45 // |----------------------------------------------| 46 // | Parameter area for this function | 47 // |----------------------------------------------| 48 // | Register save area (RSA) for this function | 49 // |----------------------------------------------| 50 // | Return address for this function | 51 // |----------------------------------------------| 52 // | Frame pointer for this function | 53 // |----------------------------------------------| <- fp(=old sp) 54 // |.empty.space.to.make.part.below.aligned.in....| 55 // |.case.it.needs.more.than.the.standard.16-byte.| (size of this area is 56 // |.alignment....................................| unknown at compile time) 57 // |----------------------------------------------| 58 // | Local variables of fixed size including spill| 59 // | slots | 60 // |----------------------------------------------| <- bp(not defined by ABI, 61 // |.variable-sized.local.variables.(VLAs)........| LLVM chooses SX17) 62 // |..............................................| (size of this area is 63 // |..............................................| unknown at compile time) 64 // |----------------------------------------------| <- stack top (returned by 65 // | Parameter area for callee | alloca) 66 // |----------------------------------------------| 67 // | Register save area (RSA) for callee | 68 // |----------------------------------------------| 69 // | Return address for callee | 70 // |----------------------------------------------| 71 // | Frame pointer for callee | 72 // |----------------------------------------------| <- sp 73 // | | Lower address 74 // 75 // To access the data in a frame, at-compile time, a constant offset must be 76 // computable from one of the pointers (fp, bp, sp) to access it. The size 77 // of the areas with a dotted background cannot be computed at compile-time 78 // if they are present, making it required to have all three of fp, bp and 79 // sp to be set up to be able to access all contents in the frame areas, 80 // assuming all of the frame areas are non-empty. 81 // 82 // For most functions, some of the frame areas are empty. For those functions, 83 // it may not be necessary to set up fp or bp: 84 // * A base pointer is definitely needed when there are both VLAs and local 85 // variables with more-than-default alignment requirements. 86 // * A frame pointer is definitely needed when there are local variables with 87 // more-than-default alignment requirements. 88 // 89 // In addition, VE ABI defines RSA frame, return address, and frame pointer 90 // as follows: 91 // 92 // |----------------------------------------------| <- sp+176 93 // | %s18...%s33 | 94 // |----------------------------------------------| <- sp+48 95 // | Linkage area register (%s17) | 96 // |----------------------------------------------| <- sp+40 97 // | Procedure linkage table register (%plt=%s16) | 98 // |----------------------------------------------| <- sp+32 99 // | Global offset table register (%got=%s15) | 100 // |----------------------------------------------| <- sp+24 101 // | Thread pointer register (%tp=%s14) | 102 // |----------------------------------------------| <- sp+16 103 // | Return address | 104 // |----------------------------------------------| <- sp+8 105 // | Frame pointer | 106 // |----------------------------------------------| <- sp+0 107 // 108 // NOTE: This description is based on VE ABI and description in 109 // AArch64FrameLowering.cpp. Thanks a lot. 110 //===----------------------------------------------------------------------===// 111 112 #include "VEFrameLowering.h" 113 #include "VEInstrInfo.h" 114 #include "VEMachineFunctionInfo.h" 115 #include "VESubtarget.h" 116 #include "llvm/CodeGen/MachineFrameInfo.h" 117 #include "llvm/CodeGen/MachineFunction.h" 118 #include "llvm/CodeGen/MachineInstrBuilder.h" 119 #include "llvm/CodeGen/MachineModuleInfo.h" 120 #include "llvm/CodeGen/MachineRegisterInfo.h" 121 #include "llvm/CodeGen/RegisterScavenging.h" 122 #include "llvm/IR/DataLayout.h" 123 #include "llvm/IR/Function.h" 124 #include "llvm/Support/CommandLine.h" 125 #include "llvm/Target/TargetOptions.h" 126 #include "llvm/Support/MathExtras.h" 127 128 using namespace llvm; 129 130 VEFrameLowering::VEFrameLowering(const VESubtarget &ST) 131 : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, Align(16), 0, 132 Align(16)), 133 STI(ST) {} 134 135 void VEFrameLowering::emitPrologueInsns(MachineFunction &MF, 136 MachineBasicBlock &MBB, 137 MachineBasicBlock::iterator MBBI, 138 uint64_t NumBytes, 139 bool RequireFPUpdate) const { 140 const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 141 DebugLoc DL; 142 const VEInstrInfo &TII = *STI.getInstrInfo(); 143 144 // Insert following codes here as prologue 145 // 146 // st %fp, 0(, %sp) iff !isLeafProc 147 // st %lr, 8(, %sp) iff !isLeafProc 148 // st %got, 24(, %sp) iff hasGOT 149 // st %plt, 32(, %sp) iff hasGOT 150 // st %s17, 40(, %sp) iff hasBP 151 if (!FuncInfo->isLeafProc()) { 152 BuildMI(MBB, MBBI, DL, TII.get(VE::STrii)) 153 .addReg(VE::SX11) 154 .addImm(0) 155 .addImm(0) 156 .addReg(VE::SX9); 157 BuildMI(MBB, MBBI, DL, TII.get(VE::STrii)) 158 .addReg(VE::SX11) 159 .addImm(0) 160 .addImm(8) 161 .addReg(VE::SX10); 162 } 163 if (hasGOT(MF)) { 164 BuildMI(MBB, MBBI, DL, TII.get(VE::STrii)) 165 .addReg(VE::SX11) 166 .addImm(0) 167 .addImm(24) 168 .addReg(VE::SX15); 169 BuildMI(MBB, MBBI, DL, TII.get(VE::STrii)) 170 .addReg(VE::SX11) 171 .addImm(0) 172 .addImm(32) 173 .addReg(VE::SX16); 174 } 175 if (hasBP(MF)) 176 BuildMI(MBB, MBBI, DL, TII.get(VE::STrii)) 177 .addReg(VE::SX11) 178 .addImm(0) 179 .addImm(40) 180 .addReg(VE::SX17); 181 } 182 183 void VEFrameLowering::emitEpilogueInsns(MachineFunction &MF, 184 MachineBasicBlock &MBB, 185 MachineBasicBlock::iterator MBBI, 186 uint64_t NumBytes, 187 bool RequireFPUpdate) const { 188 const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 189 DebugLoc DL; 190 const VEInstrInfo &TII = *STI.getInstrInfo(); 191 192 // Insert following codes here as epilogue 193 // 194 // ld %s17, 40(, %sp) iff hasBP 195 // ld %plt, 32(, %sp) iff hasGOT 196 // ld %got, 24(, %sp) iff hasGOT 197 // ld %lr, 8(, %sp) iff !isLeafProc 198 // ld %fp, 0(, %sp) iff !isLeafProc 199 if (hasBP(MF)) 200 BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX17) 201 .addReg(VE::SX11) 202 .addImm(0) 203 .addImm(40); 204 if (hasGOT(MF)) { 205 BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX16) 206 .addReg(VE::SX11) 207 .addImm(0) 208 .addImm(32); 209 BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX15) 210 .addReg(VE::SX11) 211 .addImm(0) 212 .addImm(24); 213 } 214 if (!FuncInfo->isLeafProc()) { 215 BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX10) 216 .addReg(VE::SX11) 217 .addImm(0) 218 .addImm(8); 219 BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX9) 220 .addReg(VE::SX11) 221 .addImm(0) 222 .addImm(0); 223 } 224 } 225 226 void VEFrameLowering::emitSPAdjustment(MachineFunction &MF, 227 MachineBasicBlock &MBB, 228 MachineBasicBlock::iterator MBBI, 229 int64_t NumBytes, 230 MaybeAlign MaybeAlign) const { 231 DebugLoc DL; 232 const VEInstrInfo &TII = *STI.getInstrInfo(); 233 234 if (NumBytes == 0) { 235 // Nothing to do here. 236 } else if (isInt<7>(NumBytes)) { 237 // adds.l %s11, NumBytes@lo, %s11 238 BuildMI(MBB, MBBI, DL, TII.get(VE::ADDSLri), VE::SX11) 239 .addReg(VE::SX11) 240 .addImm(NumBytes); 241 } else if (isInt<32>(NumBytes)) { 242 // lea %s11, NumBytes@lo(, %s11) 243 BuildMI(MBB, MBBI, DL, TII.get(VE::LEArii), VE::SX11) 244 .addReg(VE::SX11) 245 .addImm(0) 246 .addImm(Lo_32(NumBytes)); 247 } else { 248 // Emit following codes. This clobbers SX13 which we always know is 249 // available here. 250 // lea %s13, NumBytes@lo 251 // and %s13, %s13, (32)0 252 // lea.sl %sp, NumBytes@hi(%s13, %sp) 253 BuildMI(MBB, MBBI, DL, TII.get(VE::LEAzii), VE::SX13) 254 .addImm(0) 255 .addImm(0) 256 .addImm(Lo_32(NumBytes)); 257 BuildMI(MBB, MBBI, DL, TII.get(VE::ANDrm), VE::SX13) 258 .addReg(VE::SX13) 259 .addImm(M0(32)); 260 BuildMI(MBB, MBBI, DL, TII.get(VE::LEASLrri), VE::SX11) 261 .addReg(VE::SX11) 262 .addReg(VE::SX13) 263 .addImm(Hi_32(NumBytes)); 264 } 265 266 if (MaybeAlign) { 267 // and %sp, %sp, Align-1 268 BuildMI(MBB, MBBI, DL, TII.get(VE::ANDrm), VE::SX11) 269 .addReg(VE::SX11) 270 .addImm(M1(64 - Log2_64(MaybeAlign.valueOrOne().value()))); 271 } 272 } 273 274 void VEFrameLowering::emitSPExtend(MachineFunction &MF, MachineBasicBlock &MBB, 275 MachineBasicBlock::iterator MBBI) const { 276 DebugLoc DL; 277 const VEInstrInfo &TII = *STI.getInstrInfo(); 278 279 // Emit following codes. It is not possible to insert multiple 280 // BasicBlocks in PEI pass, so we emit two pseudo instructions here. 281 // 282 // EXTEND_STACK // pseudo instrcution 283 // EXTEND_STACK_GUARD // pseudo instrcution 284 // 285 // EXTEND_STACK pseudo will be converted by ExpandPostRA pass into 286 // following instructions with multiple basic blocks later. 287 // 288 // thisBB: 289 // brge.l.t %sp, %sl, sinkBB 290 // syscallBB: 291 // ld %s61, 0x18(, %tp) // load param area 292 // or %s62, 0, %s0 // spill the value of %s0 293 // lea %s63, 0x13b // syscall # of grow 294 // shm.l %s63, 0x0(%s61) // store syscall # at addr:0 295 // shm.l %sl, 0x8(%s61) // store old limit at addr:8 296 // shm.l %sp, 0x10(%s61) // store new limit at addr:16 297 // monc // call monitor 298 // or %s0, 0, %s62 // restore the value of %s0 299 // sinkBB: 300 // 301 // EXTEND_STACK_GUARD pseudo will be simply eliminated by ExpandPostRA 302 // pass. This pseudo is required to be at the next of EXTEND_STACK 303 // pseudo in order to protect iteration loop in ExpandPostRA. 304 BuildMI(MBB, MBBI, DL, TII.get(VE::EXTEND_STACK)); 305 BuildMI(MBB, MBBI, DL, TII.get(VE::EXTEND_STACK_GUARD)); 306 } 307 308 void VEFrameLowering::emitPrologue(MachineFunction &MF, 309 MachineBasicBlock &MBB) const { 310 const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 311 assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported"); 312 MachineFrameInfo &MFI = MF.getFrameInfo(); 313 const VEInstrInfo &TII = *STI.getInstrInfo(); 314 const VERegisterInfo &RegInfo = *STI.getRegisterInfo(); 315 MachineBasicBlock::iterator MBBI = MBB.begin(); 316 bool NeedsStackRealignment = RegInfo.shouldRealignStack(MF); 317 318 // Debug location must be unknown since the first debug location is used 319 // to determine the end of the prologue. 320 DebugLoc DL; 321 322 if (NeedsStackRealignment && !RegInfo.canRealignStack(MF)) 323 report_fatal_error("Function \"" + Twine(MF.getName()) + 324 "\" required " 325 "stack re-alignment, but LLVM couldn't handle it " 326 "(probably because it has a dynamic alloca)."); 327 328 // Get the number of bytes to allocate from the FrameInfo. 329 // This number of bytes is already aligned to ABI stack alignment. 330 uint64_t NumBytes = MFI.getStackSize(); 331 332 // Adjust stack size if this function is not a leaf function since the 333 // VE ABI requires a reserved area at the top of stack as described in 334 // VEFrameLowering.cpp. 335 if (!FuncInfo->isLeafProc()) { 336 // NOTE: The number is aligned to ABI stack alignment after adjustment. 337 NumBytes = STI.getAdjustedFrameSize(NumBytes); 338 } 339 340 // Finally, ensure that the size is sufficiently aligned for the 341 // data on the stack. 342 NumBytes = alignTo(NumBytes, MFI.getMaxAlign()); 343 344 // Update stack size with corrected value. 345 MFI.setStackSize(NumBytes); 346 347 // Emit Prologue instructions to save multiple registers. 348 emitPrologueInsns(MF, MBB, MBBI, NumBytes, true); 349 350 // Emit instructions to save SP in FP as follows if this is not a leaf 351 // function: 352 // or %fp, 0, %sp 353 if (!FuncInfo->isLeafProc()) 354 BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX9) 355 .addReg(VE::SX11) 356 .addImm(0); 357 358 // Emit stack adjust instructions 359 MaybeAlign RuntimeAlign = 360 NeedsStackRealignment ? MaybeAlign(MFI.getMaxAlign()) : std::nullopt; 361 assert((RuntimeAlign == std::nullopt || !FuncInfo->isLeafProc()) && 362 "SP has to be saved in order to align variable sized stack object!"); 363 emitSPAdjustment(MF, MBB, MBBI, -(int64_t)NumBytes, RuntimeAlign); 364 365 if (hasBP(MF)) { 366 // Copy SP to BP. 367 BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX17) 368 .addReg(VE::SX11) 369 .addImm(0); 370 } 371 372 // Emit stack extend instructions 373 if (NumBytes != 0) 374 emitSPExtend(MF, MBB, MBBI); 375 } 376 377 MachineBasicBlock::iterator VEFrameLowering::eliminateCallFramePseudoInstr( 378 MachineFunction &MF, MachineBasicBlock &MBB, 379 MachineBasicBlock::iterator I) const { 380 if (!hasReservedCallFrame(MF)) { 381 MachineInstr &MI = *I; 382 int64_t Size = MI.getOperand(0).getImm(); 383 if (MI.getOpcode() == VE::ADJCALLSTACKDOWN) 384 Size = -Size; 385 386 if (Size) 387 emitSPAdjustment(MF, MBB, I, Size); 388 } 389 return MBB.erase(I); 390 } 391 392 void VEFrameLowering::emitEpilogue(MachineFunction &MF, 393 MachineBasicBlock &MBB) const { 394 const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 395 DebugLoc DL; 396 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 397 MachineFrameInfo &MFI = MF.getFrameInfo(); 398 const VEInstrInfo &TII = *STI.getInstrInfo(); 399 400 uint64_t NumBytes = MFI.getStackSize(); 401 402 // Emit instructions to retrieve original SP. 403 if (!FuncInfo->isLeafProc()) { 404 // If SP is saved in FP, retrieve it as follows: 405 // or %sp, 0, %fp iff !isLeafProc 406 BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX11) 407 .addReg(VE::SX9) 408 .addImm(0); 409 } else { 410 // Emit stack adjust instructions. 411 emitSPAdjustment(MF, MBB, MBBI, NumBytes, std::nullopt); 412 } 413 414 // Emit Epilogue instructions to restore multiple registers. 415 emitEpilogueInsns(MF, MBB, MBBI, NumBytes, true); 416 } 417 418 // hasFP - Return true if the specified function should have a dedicated frame 419 // pointer register. This is true if the function has variable sized allocas 420 // or if frame pointer elimination is disabled. 421 bool VEFrameLowering::hasFP(const MachineFunction &MF) const { 422 const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo(); 423 424 const MachineFrameInfo &MFI = MF.getFrameInfo(); 425 return MF.getTarget().Options.DisableFramePointerElim(MF) || 426 RegInfo->hasStackRealignment(MF) || MFI.hasVarSizedObjects() || 427 MFI.isFrameAddressTaken(); 428 } 429 430 bool VEFrameLowering::hasBP(const MachineFunction &MF) const { 431 const MachineFrameInfo &MFI = MF.getFrameInfo(); 432 const TargetRegisterInfo *TRI = STI.getRegisterInfo(); 433 434 return MFI.hasVarSizedObjects() && TRI->hasStackRealignment(MF); 435 } 436 437 bool VEFrameLowering::hasGOT(const MachineFunction &MF) const { 438 const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 439 440 // If a global base register is assigned (!= 0), GOT is used. 441 return FuncInfo->getGlobalBaseReg() != 0; 442 } 443 444 StackOffset VEFrameLowering::getFrameIndexReference(const MachineFunction &MF, 445 int FI, 446 Register &FrameReg) const { 447 const MachineFrameInfo &MFI = MF.getFrameInfo(); 448 const VERegisterInfo *RegInfo = STI.getRegisterInfo(); 449 bool isFixed = MFI.isFixedObjectIndex(FI); 450 451 int64_t FrameOffset = MF.getFrameInfo().getObjectOffset(FI); 452 453 if (!hasFP(MF)) { 454 // If FP is not used, frame indexies are based on a %sp regiter. 455 FrameReg = VE::SX11; // %sp 456 return StackOffset::getFixed(FrameOffset + 457 MF.getFrameInfo().getStackSize()); 458 } 459 if (RegInfo->hasStackRealignment(MF) && !isFixed) { 460 // If data on stack require realignemnt, frame indexies are based on a %sp 461 // or %s17 (bp) register. If there is a variable sized object, bp is used. 462 if (hasBP(MF)) 463 FrameReg = VE::SX17; // %bp 464 else 465 FrameReg = VE::SX11; // %sp 466 return StackOffset::getFixed(FrameOffset + 467 MF.getFrameInfo().getStackSize()); 468 } 469 // Use %fp by default. 470 FrameReg = RegInfo->getFrameRegister(MF); 471 return StackOffset::getFixed(FrameOffset); 472 } 473 474 bool VEFrameLowering::isLeafProc(MachineFunction &MF) const { 475 476 MachineRegisterInfo &MRI = MF.getRegInfo(); 477 MachineFrameInfo &MFI = MF.getFrameInfo(); 478 479 return !MFI.hasCalls() // No calls 480 && !MRI.isPhysRegUsed(VE::SX18) // Registers within limits 481 // (s18 is first CSR) 482 && !MRI.isPhysRegUsed(VE::SX11) // %sp un-used 483 && !hasFP(MF); // Don't need %fp 484 } 485 486 void VEFrameLowering::determineCalleeSaves(MachineFunction &MF, 487 BitVector &SavedRegs, 488 RegScavenger *RS) const { 489 TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS); 490 491 // Functions having BP need to emit prologue and epilogue to allocate local 492 // buffer on the stack even if the function is a leaf function. 493 if (isLeafProc(MF) && !hasBP(MF)) { 494 VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>(); 495 FuncInfo->setLeafProc(true); 496 } 497 } 498