lib/CodeGen/IntrinsicLowering.cpp

   1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
   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 implements the IntrinsicLowering class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/CodeGen/IntrinsicLowering.h"
  14 #include "llvm/ADT/SmallVector.h"
  15 #include "llvm/IR/CallSite.h"
  16 #include "llvm/IR/Constants.h"
  17 #include "llvm/IR/DataLayout.h"
  18 #include "llvm/IR/DerivedTypes.h"
  19 #include "llvm/IR/IRBuilder.h"
  20 #include "llvm/IR/Module.h"
  21 #include "llvm/IR/Type.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/Support/raw_ostream.h"
  24 using namespace llvm;
  25
  26 /// This function is used when we want to lower an intrinsic call to a call of
  27 /// an external function. This handles hard cases such as when there was already
  28 /// a prototype for the external function, but that prototype doesn't match the
  29 /// arguments we expect to pass in.
  30 template <class ArgIt>
  31 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
  32                                  ArgIt ArgBegin, ArgIt ArgEnd,
  33                                  Type *RetTy) {
  34   // If we haven't already looked up this function, check to see if the
  35   // program already contains a function with this name.
  36   Module *M = CI->getModule();
  37   // Get or insert the definition now.
  38   std::vector<Type *> ParamTys;
  39   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  40     ParamTys.push_back((*I)->getType());
  41   FunctionCallee FCache =
  42       M->getOrInsertFunction(NewFn, FunctionType::get(RetTy, ParamTys, false));
  43
  44   IRBuilder<> Builder(CI->getParent(), CI->getIterator());
  45   SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
  46   CallInst *NewCI = Builder.CreateCall(FCache, Args);
  47   NewCI->setName(CI->getName());
  48   if (!CI->use_empty())
  49     CI->replaceAllUsesWith(NewCI);
  50   return NewCI;
  51 }
  52
  53 // VisualStudio defines setjmp as _setjmp
  54 #if defined(_MSC_VER) && defined(setjmp) && \
  55                          !defined(setjmp_undefined_for_msvc)
  56 #  pragma push_macro("setjmp")
  57 #  undef setjmp
  58 #  define setjmp_undefined_for_msvc
  59 #endif
  60
  61 /// Emit the code to lower bswap of V before the specified instruction IP.
  62 static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
  63   assert(V->getType()->isIntOrIntVectorTy() && "Can't bswap a non-integer type!");
  64
  65   unsigned BitSize = V->getType()->getScalarSizeInBits();
  66
  67   IRBuilder<> Builder(IP);
  68
  69   switch(BitSize) {
  70   default: llvm_unreachable("Unhandled type size of value to byteswap!");
  71   case 16: {
  72     Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
  73                                     "bswap.2");
  74     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
  75                                      "bswap.1");
  76     V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
  77     break;
  78   }
  79   case 32: {
  80     Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
  81                                     "bswap.4");
  82     Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
  83                                     "bswap.3");
  84     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
  85                                      "bswap.2");
  86     Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
  87                                      "bswap.1");
  88     Tmp3 = Builder.CreateAnd(Tmp3,
  89                          ConstantInt::get(V->getType(), 0xFF0000),
  90                              "bswap.and3");
  91     Tmp2 = Builder.CreateAnd(Tmp2,
  92                            ConstantInt::get(V->getType(), 0xFF00),
  93                              "bswap.and2");
  94     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
  95     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
  96     V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
  97     break;
  98   }
  99   case 64: {
 100     Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
 101                                     "bswap.8");
 102     Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
 103                                     "bswap.7");
 104     Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
 105                                     "bswap.6");
 106     Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 107                                     "bswap.5");
 108     Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 109                                      "bswap.4");
 110     Value* Tmp3 = Builder.CreateLShr(V,
 111                                      ConstantInt::get(V->getType(), 24),
 112                                      "bswap.3");
 113     Value* Tmp2 = Builder.CreateLShr(V,
 114                                      ConstantInt::get(V->getType(), 40),
 115                                      "bswap.2");
 116     Value* Tmp1 = Builder.CreateLShr(V,
 117                                      ConstantInt::get(V->getType(), 56),
 118                                      "bswap.1");
 119     Tmp7 = Builder.CreateAnd(Tmp7,
 120                              ConstantInt::get(V->getType(),
 121                                               0xFF000000000000ULL),
 122                              "bswap.and7");
 123     Tmp6 = Builder.CreateAnd(Tmp6,
 124                              ConstantInt::get(V->getType(),
 125                                               0xFF0000000000ULL),
 126                              "bswap.and6");
 127     Tmp5 = Builder.CreateAnd(Tmp5,
 128                         ConstantInt::get(V->getType(),
 129                              0xFF00000000ULL),
 130                              "bswap.and5");
 131     Tmp4 = Builder.CreateAnd(Tmp4,
 132                         ConstantInt::get(V->getType(),
 133                              0xFF000000ULL),
 134                              "bswap.and4");
 135     Tmp3 = Builder.CreateAnd(Tmp3,
 136                              ConstantInt::get(V->getType(),
 137                              0xFF0000ULL),
 138                              "bswap.and3");
 139     Tmp2 = Builder.CreateAnd(Tmp2,
 140                              ConstantInt::get(V->getType(),
 141                              0xFF00ULL),
 142                              "bswap.and2");
 143     Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
 144     Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
 145     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
 146     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
 147     Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
 148     Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
 149     V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
 150     break;
 151   }
 152   }
 153   return V;
 154 }
 155
 156 /// Emit the code to lower ctpop of V before the specified instruction IP.
 157 static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
 158   assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");
 159
 160   static const uint64_t MaskValues[6] = {
 161     0x5555555555555555ULL, 0x3333333333333333ULL,
 162     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
 163     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
 164   };
 165
 166   IRBuilder<> Builder(IP);
 167
 168   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 169   unsigned WordSize = (BitSize + 63) / 64;
 170   Value *Count = ConstantInt::get(V->getType(), 0);
 171
 172   for (unsigned n = 0; n < WordSize; ++n) {
 173     Value *PartValue = V;
 174     for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
 175          i <<= 1, ++ct) {
 176       Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
 177       Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
 178       Value *VShift = Builder.CreateLShr(PartValue,
 179                                         ConstantInt::get(V->getType(), i),
 180                                          "ctpop.sh");
 181       Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
 182       PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
 183     }
 184     Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
 185     if (BitSize > 64) {
 186       V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
 187                              "ctpop.part.sh");
 188       BitSize -= 64;
 189     }
 190   }
 191
 192   return Count;
 193 }
 194
 195 /// Emit the code to lower ctlz of V before the specified instruction IP.
 196 static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
 197
 198   IRBuilder<> Builder(IP);
 199
 200   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 201   for (unsigned i = 1; i < BitSize; i <<= 1) {
 202     Value *ShVal = ConstantInt::get(V->getType(), i);
 203     ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
 204     V = Builder.CreateOr(V, ShVal, "ctlz.step");
 205   }
 206
 207   V = Builder.CreateNot(V);
 208   return LowerCTPOP(Context, V, IP);
 209 }
 210
 211 static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
 212                                        const char *Dname,
 213                                        const char *LDname) {
 214   CallSite CS(CI);
 215   switch (CI->getArgOperand(0)->getType()->getTypeID()) {
 216   default: llvm_unreachable("Invalid type in intrinsic");
 217   case Type::FloatTyID:
 218     ReplaceCallWith(Fname, CI, CS.arg_begin(), CS.arg_end(),
 219                   Type::getFloatTy(CI->getContext()));
 220     break;
 221   case Type::DoubleTyID:
 222     ReplaceCallWith(Dname, CI, CS.arg_begin(), CS.arg_end(),
 223                   Type::getDoubleTy(CI->getContext()));
 224     break;
 225   case Type::X86_FP80TyID:
 226   case Type::FP128TyID:
 227   case Type::PPC_FP128TyID:
 228     ReplaceCallWith(LDname, CI, CS.arg_begin(), CS.arg_end(),
 229                   CI->getArgOperand(0)->getType());
 230     break;
 231   }
 232 }
 233
 234 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
 235   IRBuilder<> Builder(CI);
 236   LLVMContext &Context = CI->getContext();
 237
 238   const Function *Callee = CI->getCalledFunction();
 239   assert(Callee && "Cannot lower an indirect call!");
 240
 241   CallSite CS(CI);
 242   switch (Callee->getIntrinsicID()) {
 243   case Intrinsic::not_intrinsic:
 244     report_fatal_error("Cannot lower a call to a non-intrinsic function '"+
 245                       Callee->getName() + "'!");
 246   default:
 247     report_fatal_error("Code generator does not support intrinsic function '"+
 248                       Callee->getName()+"'!");
 249
 250   case Intrinsic::expect: {
 251     // Just replace __builtin_expect(exp, c) with EXP.
 252     Value *V = CI->getArgOperand(0);
 253     CI->replaceAllUsesWith(V);
 254     break;
 255   }
 256
 257     // The setjmp/longjmp intrinsics should only exist in the code if it was
 258     // never optimized (ie, right out of the CFE), or if it has been hacked on
 259     // by the lowerinvoke pass.  In both cases, the right thing to do is to
 260     // convert the call to an explicit setjmp or longjmp call.
 261   case Intrinsic::setjmp: {
 262     Value *V = ReplaceCallWith("setjmp", CI, CS.arg_begin(), CS.arg_end(),
 263                                Type::getInt32Ty(Context));
 264     if (!CI->getType()->isVoidTy())
 265       CI->replaceAllUsesWith(V);
 266     break;
 267   }
 268   case Intrinsic::sigsetjmp:
 269      if (!CI->getType()->isVoidTy())
 270        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 271      break;
 272
 273   case Intrinsic::longjmp: {
 274     ReplaceCallWith("longjmp", CI, CS.arg_begin(), CS.arg_end(),
 275                     Type::getVoidTy(Context));
 276     break;
 277   }
 278
 279   case Intrinsic::siglongjmp: {
 280     // Insert the call to abort
 281     ReplaceCallWith("abort", CI, CS.arg_end(), CS.arg_end(),
 282                     Type::getVoidTy(Context));
 283     break;
 284   }
 285   case Intrinsic::ctpop:
 286     CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI));
 287     break;
 288
 289   case Intrinsic::bswap:
 290     CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI));
 291     break;
 292
 293   case Intrinsic::ctlz:
 294     CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI));
 295     break;
 296
 297   case Intrinsic::cttz: {
 298     // cttz(x) -> ctpop(~X & (X-1))
 299     Value *Src = CI->getArgOperand(0);
 300     Value *NotSrc = Builder.CreateNot(Src);
 301     NotSrc->setName(Src->getName() + ".not");
 302     Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
 303     SrcM1 = Builder.CreateSub(Src, SrcM1);
 304     Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
 305     CI->replaceAllUsesWith(Src);
 306     break;
 307   }
 308
 309   case Intrinsic::stacksave:
 310   case Intrinsic::stackrestore: {
 311     if (!Warned)
 312       errs() << "WARNING: this target does not support the llvm.stack"
 313              << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
 314                "save" : "restore") << " intrinsic.\n";
 315     Warned = true;
 316     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
 317       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 318     break;
 319   }
 320
 321   case Intrinsic::get_dynamic_area_offset:
 322     errs() << "WARNING: this target does not support the custom llvm.get."
 323               "dynamic.area.offset.  It is being lowered to a constant 0\n";
 324     // Just lower it to a constant 0 because for most targets
 325     // @llvm.get.dynamic.area.offset is lowered to zero.
 326     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0));
 327     break;
 328   case Intrinsic::returnaddress:
 329   case Intrinsic::frameaddress:
 330     errs() << "WARNING: this target does not support the llvm."
 331            << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
 332              "return" : "frame") << "address intrinsic.\n";
 333     CI->replaceAllUsesWith(
 334         ConstantPointerNull::get(cast<PointerType>(CI->getType())));
 335     break;
 336   case Intrinsic::addressofreturnaddress:
 337     errs() << "WARNING: this target does not support the "
 338               "llvm.addressofreturnaddress intrinsic.\n";
 339     CI->replaceAllUsesWith(
 340         ConstantPointerNull::get(cast<PointerType>(CI->getType())));
 341     break;
 342
 343   case Intrinsic::prefetch:
 344     break;    // Simply strip out prefetches on unsupported architectures
 345
 346   case Intrinsic::pcmarker:
 347     break;    // Simply strip out pcmarker on unsupported architectures
 348   case Intrinsic::readcyclecounter: {
 349     errs() << "WARNING: this target does not support the llvm.readcyclecoun"
 350            << "ter intrinsic.  It is being lowered to a constant 0\n";
 351     CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
 352     break;
 353   }
 354
 355   case Intrinsic::dbg_declare:
 356   case Intrinsic::dbg_label:
 357     break;    // Simply strip out debugging intrinsics
 358
 359   case Intrinsic::eh_typeid_for:
 360     // Return something different to eh_selector.
 361     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 362     break;
 363
 364   case Intrinsic::annotation:
 365   case Intrinsic::ptr_annotation:
 366     // Just drop the annotation, but forward the value
 367     CI->replaceAllUsesWith(CI->getOperand(0));
 368     break;
 369
 370   case Intrinsic::assume:
 371   case Intrinsic::var_annotation:
 372     break;   // Strip out these intrinsics
 373
 374   case Intrinsic::memcpy: {
 375     Type *IntPtr = DL.getIntPtrType(Context);
 376     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
 377                                         /* isSigned */ false);
 378     Value *Ops[3];
 379     Ops[0] = CI->getArgOperand(0);
 380     Ops[1] = CI->getArgOperand(1);
 381     Ops[2] = Size;
 382     ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
 383     break;
 384   }
 385   case Intrinsic::memmove: {
 386     Type *IntPtr = DL.getIntPtrType(Context);
 387     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
 388                                         /* isSigned */ false);
 389     Value *Ops[3];
 390     Ops[0] = CI->getArgOperand(0);
 391     Ops[1] = CI->getArgOperand(1);
 392     Ops[2] = Size;
 393     ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
 394     break;
 395   }
 396   case Intrinsic::memset: {
 397     Value *Op0 = CI->getArgOperand(0);
 398     Type *IntPtr = DL.getIntPtrType(Op0->getType());
 399     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
 400                                         /* isSigned */ false);
 401     Value *Ops[3];
 402     Ops[0] = Op0;
 403     // Extend the amount to i32.
 404     Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1),
 405                                    Type::getInt32Ty(Context),
 406                                    /* isSigned */ false);
 407     Ops[2] = Size;
 408     ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
 409     break;
 410   }
 411   case Intrinsic::sqrt: {
 412     ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
 413     break;
 414   }
 415   case Intrinsic::log: {
 416     ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
 417     break;
 418   }
 419   case Intrinsic::log2: {
 420     ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
 421     break;
 422   }
 423   case Intrinsic::log10: {
 424     ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
 425     break;
 426   }
 427   case Intrinsic::exp: {
 428     ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
 429     break;
 430   }
 431   case Intrinsic::exp2: {
 432     ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
 433     break;
 434   }
 435   case Intrinsic::pow: {
 436     ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
 437     break;
 438   }
 439   case Intrinsic::sin: {
 440     ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl");
 441     break;
 442   }
 443   case Intrinsic::cos: {
 444     ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl");
 445     break;
 446   }
 447   case Intrinsic::floor: {
 448     ReplaceFPIntrinsicWithCall(CI, "floorf", "floor", "floorl");
 449     break;
 450   }
 451   case Intrinsic::ceil: {
 452     ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill");
 453     break;
 454   }
 455   case Intrinsic::trunc: {
 456     ReplaceFPIntrinsicWithCall(CI, "truncf", "trunc", "truncl");
 457     break;
 458   }
 459   case Intrinsic::round: {
 460     ReplaceFPIntrinsicWithCall(CI, "roundf", "round", "roundl");
 461     break;
 462   }
 463   case Intrinsic::copysign: {
 464     ReplaceFPIntrinsicWithCall(CI, "copysignf", "copysign", "copysignl");
 465     break;
 466   }
 467   case Intrinsic::flt_rounds:
 468      // Lower to "round to the nearest"
 469      if (!CI->getType()->isVoidTy())
 470        CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 471      break;
 472   case Intrinsic::invariant_start:
 473   case Intrinsic::lifetime_start:
 474     // Discard region information.
 475     CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
 476     break;
 477   case Intrinsic::invariant_end:
 478   case Intrinsic::lifetime_end:
 479     // Discard region information.
 480     break;
 481   }
 482
 483   assert(CI->use_empty() &&
 484          "Lowering should have eliminated any uses of the intrinsic call!");
 485   CI->eraseFromParent();
 486 }
 487
 488 bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) {
 489   // Verify this is a simple bswap.
 490   if (CI->getNumArgOperands() != 1 ||
 491       CI->getType() != CI->getArgOperand(0)->getType() ||
 492       !CI->getType()->isIntegerTy())
 493     return false;
 494
 495   IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
 496   if (!Ty)
 497     return false;
 498
 499   // Okay, we can do this xform, do so now.
 500   Module *M = CI->getModule();
 501   Function *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty);
 502
 503   Value *Op = CI->getArgOperand(0);
 504   Op = CallInst::Create(Int, Op, CI->getName(), CI);
 505
 506   CI->replaceAllUsesWith(Op);
 507   CI->eraseFromParent();
 508   return true;
 509 }