llvm/lib/CodeGen/ExpandLargeFpConvert.cpp

   1 //===--- ExpandLargeFpConvert.cpp - Expand large fp convert----------------===//
   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
  10 // This pass expands ‘fptoui .. to’, ‘fptosi .. to’, ‘uitofp .. to’,
  11 // ‘sitofp .. to’ instructions with a bitwidth above a threshold into
  12 // auto-generated functions. This is useful for targets like x86_64 that cannot
  13 // lower fp convertions with more than 128 bits.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/CodeGen/ExpandLargeFpConvert.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/Analysis/GlobalsModRef.h"
  20 #include "llvm/CodeGen/Passes.h"
  21 #include "llvm/CodeGen/TargetLowering.h"
  22 #include "llvm/CodeGen/TargetPassConfig.h"
  23 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  24 #include "llvm/IR/IRBuilder.h"
  25 #include "llvm/IR/InstIterator.h"
  26 #include "llvm/IR/PassManager.h"
  27 #include "llvm/InitializePasses.h"
  28 #include "llvm/Pass.h"
  29 #include "llvm/Support/CommandLine.h"
  30 #include "llvm/Target/TargetMachine.h"
  31
  32 using namespace llvm;
  33
  34 static cl::opt<unsigned>
  35     ExpandFpConvertBits("expand-fp-convert-bits", cl::Hidden,
  36                      cl::init(llvm::IntegerType::MAX_INT_BITS),
  37                      cl::desc("fp convert instructions on integers with "
  38                               "more than <N> bits are expanded."));
  39
  40 /// Generate code to convert a fp number to integer, replacing FPToS(U)I with
  41 /// the generated code. This currently generates code similarly to compiler-rt's
  42 /// implementations.
  43 ///
  44 /// An example IR generated from compiler-rt/fixsfdi.c looks like below:
  45 /// define dso_local i64 @foo(float noundef %a) local_unnamed_addr #0 {
  46 /// entry:
  47 ///   %0 = bitcast float %a to i32
  48 ///   %conv.i = zext i32 %0 to i64
  49 ///   %tobool.not = icmp sgt i32 %0, -1
  50 ///   %conv = select i1 %tobool.not, i64 1, i64 -1
  51 ///   %and = lshr i64 %conv.i, 23
  52 ///   %shr = and i64 %and, 255
  53 ///   %and2 = and i64 %conv.i, 8388607
  54 ///   %or = or i64 %and2, 8388608
  55 ///   %cmp = icmp ult i64 %shr, 127
  56 ///   br i1 %cmp, label %cleanup, label %if.end
  57 ///
  58 /// if.end:                                           ; preds = %entry
  59 ///   %sub = add nuw nsw i64 %shr, 4294967169
  60 ///   %conv5 = and i64 %sub, 4294967232
  61 ///   %cmp6.not = icmp eq i64 %conv5, 0
  62 ///   br i1 %cmp6.not, label %if.end12, label %if.then8
  63 ///
  64 /// if.then8:                                         ; preds = %if.end
  65 ///   %cond11 = select i1 %tobool.not, i64 9223372036854775807, i64 -9223372036854775808
  66 ///   br label %cleanup
  67 ///
  68 /// if.end12:                                         ; preds = %if.end
  69 ///   %cmp13 = icmp ult i64 %shr, 150
  70 ///   br i1 %cmp13, label %if.then15, label %if.else
  71 ///
  72 /// if.then15:                                        ; preds = %if.end12
  73 ///   %sub16 = sub nuw nsw i64 150, %shr
  74 ///   %shr17 = lshr i64 %or, %sub16
  75 ///   %mul = mul nsw i64 %shr17, %conv
  76 ///   br label %cleanup
  77 ///
  78 /// if.else:                                          ; preds = %if.end12
  79 ///   %sub18 = add nsw i64 %shr, -150
  80 ///   %shl = shl i64 %or, %sub18
  81 ///   %mul19 = mul nsw i64 %shl, %conv
  82 ///   br label %cleanup
  83 ///
  84 /// cleanup:                                          ; preds = %entry, %if.else, %if.then15, %if.then8
  85 ///   %retval.0 = phi i64 [ %cond11, %if.then8 ], [ %mul, %if.then15 ], [ %mul19, %if.else ], [ 0, %entry ]
  86 ///   ret i64 %retval.0
  87 /// }
  88 ///
  89 /// Replace fp to integer with generated code.
  90 static void expandFPToI(Instruction *FPToI) {
  91   IRBuilder<> Builder(FPToI);
  92   auto *FloatVal = FPToI->getOperand(0);
  93   IntegerType *IntTy = cast<IntegerType>(FPToI->getType());
  94
  95   unsigned BitWidth = FPToI->getType()->getIntegerBitWidth();
  96   unsigned FPMantissaWidth = FloatVal->getType()->getFPMantissaWidth() - 1;
  97
  98   // FIXME: fp16's range is covered by i32. So `fptoi half` can convert
  99   // to i32 first following a sext/zext to target integer type.
 100   Value *A1 = nullptr;
 101   if (FloatVal->getType()->isHalfTy()) {
 102     if (FPToI->getOpcode() == Instruction::FPToUI) {
 103       Value *A0 = Builder.CreateFPToUI(FloatVal, Builder.getIntNTy(32));
 104       A1 = Builder.CreateZExt(A0, IntTy);
 105     } else { // FPToSI
 106       Value *A0 = Builder.CreateFPToSI(FloatVal, Builder.getIntNTy(32));
 107       A1 = Builder.CreateSExt(A0, IntTy);
 108     }
 109     FPToI->replaceAllUsesWith(A1);
 110     FPToI->dropAllReferences();
 111     FPToI->eraseFromParent();
 112     return;
 113   }
 114
 115   // fp80 conversion is implemented by fpext to fp128 first then do the
 116   // conversion.
 117   FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
 118   unsigned FloatWidth =
 119       PowerOf2Ceil(FloatVal->getType()->getScalarSizeInBits());
 120   unsigned ExponentWidth = FloatWidth - FPMantissaWidth - 1;
 121   unsigned ExponentBias = (1 << (ExponentWidth - 1)) - 1;
 122   Value *ImplicitBit = Builder.CreateShl(
 123       Builder.getIntN(BitWidth, 1), Builder.getIntN(BitWidth, FPMantissaWidth));
 124   Value *SignificandMask =
 125       Builder.CreateSub(ImplicitBit, Builder.getIntN(BitWidth, 1));
 126   Value *NegOne = Builder.CreateSExt(
 127       ConstantInt::getSigned(Builder.getInt32Ty(), -1), IntTy);
 128   Value *NegInf =
 129       Builder.CreateShl(ConstantInt::getSigned(IntTy, 1),
 130                         ConstantInt::getSigned(IntTy, BitWidth - 1));
 131
 132   BasicBlock *Entry = Builder.GetInsertBlock();
 133   Function *F = Entry->getParent();
 134   Entry->setName(Twine(Entry->getName(), "fp-to-i-entry"));
 135   BasicBlock *End =
 136       Entry->splitBasicBlock(Builder.GetInsertPoint(), "fp-to-i-cleanup");
 137   BasicBlock *IfEnd =
 138       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end", F, End);
 139   BasicBlock *IfThen5 =
 140       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then5", F, End);
 141   BasicBlock *IfEnd9 =
 142       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end9", F, End);
 143   BasicBlock *IfThen12 =
 144       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then12", F, End);
 145   BasicBlock *IfElse =
 146       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-else", F, End);
 147
 148   Entry->getTerminator()->eraseFromParent();
 149
 150   // entry:
 151   Builder.SetInsertPoint(Entry);
 152   Value *FloatVal0 = FloatVal;
 153   // fp80 conversion is implemented by fpext to fp128 first then do the
 154   // conversion.
 155   if (FloatVal->getType()->isX86_FP80Ty())
 156     FloatVal0 =
 157         Builder.CreateFPExt(FloatVal, Type::getFP128Ty(Builder.getContext()));
 158   Value *ARep0 =
 159       Builder.CreateBitCast(FloatVal0, Builder.getIntNTy(FloatWidth));
 160   Value *ARep = Builder.CreateZExt(ARep0, FPToI->getType());
 161   Value *PosOrNeg = Builder.CreateICmpSGT(
 162       ARep0, ConstantInt::getSigned(Builder.getIntNTy(FloatWidth), -1));
 163   Value *Sign = Builder.CreateSelect(PosOrNeg, ConstantInt::getSigned(IntTy, 1),
 164                                      ConstantInt::getSigned(IntTy, -1));
 165   Value *And =
 166       Builder.CreateLShr(ARep, Builder.getIntN(BitWidth, FPMantissaWidth));
 167   Value *And2 = Builder.CreateAnd(
 168       And, Builder.getIntN(BitWidth, (1 << ExponentWidth) - 1));
 169   Value *Abs = Builder.CreateAnd(ARep, SignificandMask);
 170   Value *Or = Builder.CreateOr(Abs, ImplicitBit);
 171   Value *Cmp =
 172       Builder.CreateICmpULT(And2, Builder.getIntN(BitWidth, ExponentBias));
 173   Builder.CreateCondBr(Cmp, End, IfEnd);
 174
 175   // if.end:
 176   Builder.SetInsertPoint(IfEnd);
 177   Value *Add1 = Builder.CreateAdd(
 178       And2, ConstantInt::getSigned(
 179                 IntTy, -static_cast<int64_t>(ExponentBias + BitWidth)));
 180   Value *Cmp3 = Builder.CreateICmpULT(
 181       Add1, ConstantInt::getSigned(IntTy, -static_cast<int64_t>(BitWidth)));
 182   Builder.CreateCondBr(Cmp3, IfThen5, IfEnd9);
 183
 184   // if.then5:
 185   Builder.SetInsertPoint(IfThen5);
 186   Value *PosInf = Builder.CreateXor(NegOne, NegInf);
 187   Value *Cond8 = Builder.CreateSelect(PosOrNeg, PosInf, NegInf);
 188   Builder.CreateBr(End);
 189
 190   // if.end9:
 191   Builder.SetInsertPoint(IfEnd9);
 192   Value *Cmp10 = Builder.CreateICmpULT(
 193       And2, Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth));
 194   Builder.CreateCondBr(Cmp10, IfThen12, IfElse);
 195
 196   // if.then12:
 197   Builder.SetInsertPoint(IfThen12);
 198   Value *Sub13 = Builder.CreateSub(
 199       Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth), And2);
 200   Value *Shr14 = Builder.CreateLShr(Or, Sub13);
 201   Value *Mul = Builder.CreateMul(Shr14, Sign);
 202   Builder.CreateBr(End);
 203
 204   // if.else:
 205   Builder.SetInsertPoint(IfElse);
 206   Value *Sub15 = Builder.CreateAdd(
 207       And2, ConstantInt::getSigned(
 208                 IntTy, -static_cast<int64_t>(ExponentBias + FPMantissaWidth)));
 209   Value *Shl = Builder.CreateShl(Or, Sub15);
 210   Value *Mul16 = Builder.CreateMul(Shl, Sign);
 211   Builder.CreateBr(End);
 212
 213   // cleanup:
 214   Builder.SetInsertPoint(End, End->begin());
 215   PHINode *Retval0 = Builder.CreatePHI(FPToI->getType(), 4);
 216
 217   Retval0->addIncoming(Cond8, IfThen5);
 218   Retval0->addIncoming(Mul, IfThen12);
 219   Retval0->addIncoming(Mul16, IfElse);
 220   Retval0->addIncoming(Builder.getIntN(BitWidth, 0), Entry);
 221
 222   FPToI->replaceAllUsesWith(Retval0);
 223   FPToI->dropAllReferences();
 224   FPToI->eraseFromParent();
 225 }
 226
 227 /// Generate code to convert a fp number to integer, replacing S(U)IToFP with
 228 /// the generated code. This currently generates code similarly to compiler-rt's
 229 /// implementations. This implementation has an implicit assumption that integer
 230 /// width is larger than fp.
 231 ///
 232 /// An example IR generated from compiler-rt/floatdisf.c looks like below:
 233 /// define dso_local float @__floatdisf(i64 noundef %a) local_unnamed_addr #0 {
 234 /// entry:
 235 ///   %cmp = icmp eq i64 %a, 0
 236 ///   br i1 %cmp, label %return, label %if.end
 237 ///
 238 /// if.end:                                           ; preds = %entry
 239 ///   %shr = ashr i64 %a, 63
 240 ///   %xor = xor i64 %shr, %a
 241 ///   %sub = sub nsw i64 %xor, %shr
 242 ///   %0 = tail call i64 @llvm.ctlz.i64(i64 %sub, i1 true), !range !5
 243 ///   %cast = trunc i64 %0 to i32
 244 ///   %sub1 = sub nuw nsw i32 64, %cast
 245 ///   %sub2 = xor i32 %cast, 63
 246 ///   %cmp3 = icmp ult i32 %cast, 40
 247 ///   br i1 %cmp3, label %if.then4, label %if.else
 248 ///
 249 /// if.then4:                                         ; preds = %if.end
 250 ///   switch i32 %sub1, label %sw.default [
 251 ///     i32 25, label %sw.bb
 252 ///     i32 26, label %sw.epilog
 253 ///   ]
 254 ///
 255 /// sw.bb:                                            ; preds = %if.then4
 256 ///   %shl = shl i64 %sub, 1
 257 ///   br label %sw.epilog
 258 ///
 259 /// sw.default:                                       ; preds = %if.then4
 260 ///   %sub5 = sub nsw i64 38, %0
 261 ///   %sh_prom = and i64 %sub5, 4294967295
 262 ///   %shr6 = lshr i64 %sub, %sh_prom
 263 ///   %shr9 = lshr i64 274877906943, %0
 264 ///   %and = and i64 %shr9, %sub
 265 ///   %cmp10 = icmp ne i64 %and, 0
 266 ///   %conv11 = zext i1 %cmp10 to i64
 267 ///   %or = or i64 %shr6, %conv11
 268 ///   br label %sw.epilog
 269 ///
 270 /// sw.epilog:                                        ; preds = %sw.default, %if.then4, %sw.bb
 271 ///   %a.addr.0 = phi i64 [ %or, %sw.default ], [ %sub, %if.then4 ], [ %shl, %sw.bb ]
 272 ///   %1 = lshr i64 %a.addr.0, 2
 273 ///   %2 = and i64 %1, 1
 274 ///   %or16 = or i64 %2, %a.addr.0
 275 ///   %inc = add nsw i64 %or16, 1
 276 ///   %3 = and i64 %inc, 67108864
 277 ///   %tobool.not = icmp eq i64 %3, 0
 278 ///   %spec.select.v = select i1 %tobool.not, i64 2, i64 3
 279 ///   %spec.select = ashr i64 %inc, %spec.select.v
 280 ///   %spec.select56 = select i1 %tobool.not, i32 %sub2, i32 %sub1
 281 ///   br label %if.end26
 282 ///
 283 /// if.else:                                          ; preds = %if.end
 284 ///   %sub23 = add nuw nsw i64 %0, 4294967256
 285 ///   %sh_prom24 = and i64 %sub23, 4294967295
 286 ///   %shl25 = shl i64 %sub, %sh_prom24
 287 ///   br label %if.end26
 288 ///
 289 /// if.end26:                                         ; preds = %sw.epilog, %if.else
 290 ///   %a.addr.1 = phi i64 [ %shl25, %if.else ], [ %spec.select, %sw.epilog ]
 291 ///   %e.0 = phi i32 [ %sub2, %if.else ], [ %spec.select56, %sw.epilog ]
 292 ///   %conv27 = trunc i64 %shr to i32
 293 ///   %and28 = and i32 %conv27, -2147483648
 294 ///   %add = shl nuw nsw i32 %e.0, 23
 295 ///   %shl29 = add nuw nsw i32 %add, 1065353216
 296 ///   %conv31 = trunc i64 %a.addr.1 to i32
 297 ///   %and32 = and i32 %conv31, 8388607
 298 ///   %or30 = or i32 %and32, %and28
 299 ///   %or33 = or i32 %or30, %shl29
 300 ///   %4 = bitcast i32 %or33 to float
 301 ///   br label %return
 302 ///
 303 /// return:                                           ; preds = %entry, %if.end26
 304 ///   %retval.0 = phi float [ %4, %if.end26 ], [ 0.000000e+00, %entry ]
 305 ///   ret float %retval.0
 306 /// }
 307 ///
 308 /// Replace integer to fp with generated code.
 309 static void expandIToFP(Instruction *IToFP) {
 310   IRBuilder<> Builder(IToFP);
 311   auto *IntVal = IToFP->getOperand(0);
 312   IntegerType *IntTy = cast<IntegerType>(IntVal->getType());
 313
 314   unsigned BitWidth = IntVal->getType()->getIntegerBitWidth();
 315   unsigned FPMantissaWidth = IToFP->getType()->getFPMantissaWidth() - 1;
 316   // fp80 conversion is implemented by conversion tp fp128 first following
 317   // a fptrunc to fp80.
 318   FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
 319   // FIXME: As there is no related builtins added in compliler-rt,
 320   // here currently utilized the fp32 <-> fp16 lib calls to implement.
 321   FPMantissaWidth = FPMantissaWidth == 10 ? 23 : FPMantissaWidth;
 322   FPMantissaWidth = FPMantissaWidth == 7 ? 23 : FPMantissaWidth;
 323   unsigned FloatWidth = PowerOf2Ceil(FPMantissaWidth);
 324   bool IsSigned = IToFP->getOpcode() == Instruction::SIToFP;
 325
 326   assert(BitWidth > FloatWidth && "Unexpected conversion. expandIToFP() "
 327                                   "assumes integer width is larger than fp.");
 328
 329   Value *Temp1 =
 330       Builder.CreateShl(Builder.getIntN(BitWidth, 1),
 331                         Builder.getIntN(BitWidth, FPMantissaWidth + 3));
 332
 333   BasicBlock *Entry = Builder.GetInsertBlock();
 334   Function *F = Entry->getParent();
 335   Entry->setName(Twine(Entry->getName(), "itofp-entry"));
 336   BasicBlock *End =
 337       Entry->splitBasicBlock(Builder.GetInsertPoint(), "itofp-return");
 338   BasicBlock *IfEnd =
 339       BasicBlock::Create(Builder.getContext(), "itofp-if-end", F, End);
 340   BasicBlock *IfThen4 =
 341       BasicBlock::Create(Builder.getContext(), "itofp-if-then4", F, End);
 342   BasicBlock *SwBB =
 343       BasicBlock::Create(Builder.getContext(), "itofp-sw-bb", F, End);
 344   BasicBlock *SwDefault =
 345       BasicBlock::Create(Builder.getContext(), "itofp-sw-default", F, End);
 346   BasicBlock *SwEpilog =
 347       BasicBlock::Create(Builder.getContext(), "itofp-sw-epilog", F, End);
 348   BasicBlock *IfThen20 =
 349       BasicBlock::Create(Builder.getContext(), "itofp-if-then20", F, End);
 350   BasicBlock *IfElse =
 351       BasicBlock::Create(Builder.getContext(), "itofp-if-else", F, End);
 352   BasicBlock *IfEnd26 =
 353       BasicBlock::Create(Builder.getContext(), "itofp-if-end26", F, End);
 354
 355   Entry->getTerminator()->eraseFromParent();
 356
 357   Function *CTLZ =
 358       Intrinsic::getOrInsertDeclaration(F->getParent(), Intrinsic::ctlz, IntTy);
 359   ConstantInt *True = Builder.getTrue();
 360
 361   // entry:
 362   Builder.SetInsertPoint(Entry);
 363   Value *Cmp = Builder.CreateICmpEQ(IntVal, ConstantInt::getSigned(IntTy, 0));
 364   Builder.CreateCondBr(Cmp, End, IfEnd);
 365
 366   // if.end:
 367   Builder.SetInsertPoint(IfEnd);
 368   Value *Shr =
 369       Builder.CreateAShr(IntVal, Builder.getIntN(BitWidth, BitWidth - 1));
 370   Value *Xor = Builder.CreateXor(Shr, IntVal);
 371   Value *Sub = Builder.CreateSub(Xor, Shr);
 372   Value *Call = Builder.CreateCall(CTLZ, {IsSigned ? Sub : IntVal, True});
 373   Value *Cast = Builder.CreateTrunc(Call, Builder.getInt32Ty());
 374   int BitWidthNew = FloatWidth == 128 ? BitWidth : 32;
 375   Value *Sub1 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth),
 376                                   FloatWidth == 128 ? Call : Cast);
 377   Value *Sub2 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth - 1),
 378                                   FloatWidth == 128 ? Call : Cast);
 379   Value *Cmp3 = Builder.CreateICmpSGT(
 380       Sub1, Builder.getIntN(BitWidthNew, FPMantissaWidth + 1));
 381   Builder.CreateCondBr(Cmp3, IfThen4, IfElse);
 382
 383   // if.then4:
 384   Builder.SetInsertPoint(IfThen4);
 385   llvm::SwitchInst *SI = Builder.CreateSwitch(Sub1, SwDefault);
 386   SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 2), SwBB);
 387   SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 3), SwEpilog);
 388
 389   // sw.bb:
 390   Builder.SetInsertPoint(SwBB);
 391   Value *Shl =
 392       Builder.CreateShl(IsSigned ? Sub : IntVal, Builder.getIntN(BitWidth, 1));
 393   Builder.CreateBr(SwEpilog);
 394
 395   // sw.default:
 396   Builder.SetInsertPoint(SwDefault);
 397   Value *Sub5 = Builder.CreateSub(
 398       Builder.getIntN(BitWidthNew, BitWidth - FPMantissaWidth - 3),
 399       FloatWidth == 128 ? Call : Cast);
 400   Value *ShProm = Builder.CreateZExt(Sub5, IntTy);
 401   Value *Shr6 = Builder.CreateLShr(IsSigned ? Sub : IntVal,
 402                                    FloatWidth == 128 ? Sub5 : ShProm);
 403   Value *Sub8 =
 404       Builder.CreateAdd(FloatWidth == 128 ? Call : Cast,
 405                         Builder.getIntN(BitWidthNew, FPMantissaWidth + 3));
 406   Value *ShProm9 = Builder.CreateZExt(Sub8, IntTy);
 407   Value *Shr9 = Builder.CreateLShr(ConstantInt::getSigned(IntTy, -1),
 408                                    FloatWidth == 128 ? Sub8 : ShProm9);
 409   Value *And = Builder.CreateAnd(Shr9, IsSigned ? Sub : IntVal);
 410   Value *Cmp10 = Builder.CreateICmpNE(And, Builder.getIntN(BitWidth, 0));
 411   Value *Conv11 = Builder.CreateZExt(Cmp10, IntTy);
 412   Value *Or = Builder.CreateOr(Shr6, Conv11);
 413   Builder.CreateBr(SwEpilog);
 414
 415   // sw.epilog:
 416   Builder.SetInsertPoint(SwEpilog);
 417   PHINode *AAddr0 = Builder.CreatePHI(IntTy, 3);
 418   AAddr0->addIncoming(Or, SwDefault);
 419   AAddr0->addIncoming(IsSigned ? Sub : IntVal, IfThen4);
 420   AAddr0->addIncoming(Shl, SwBB);
 421   Value *A0 = Builder.CreateTrunc(AAddr0, Builder.getInt32Ty());
 422   Value *A1 = Builder.CreateLShr(A0, Builder.getIntN(32, 2));
 423   Value *A2 = Builder.CreateAnd(A1, Builder.getIntN(32, 1));
 424   Value *Conv16 = Builder.CreateZExt(A2, IntTy);
 425   Value *Or17 = Builder.CreateOr(AAddr0, Conv16);
 426   Value *Inc = Builder.CreateAdd(Or17, Builder.getIntN(BitWidth, 1));
 427   Value *Shr18 = nullptr;
 428   if (IsSigned)
 429     Shr18 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 2));
 430   else
 431     Shr18 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 2));
 432   Value *A3 = Builder.CreateAnd(Inc, Temp1, "a3");
 433   Value *PosOrNeg = Builder.CreateICmpEQ(A3, Builder.getIntN(BitWidth, 0));
 434   Value *ExtractT60 = Builder.CreateTrunc(Shr18, Builder.getIntNTy(FloatWidth));
 435   Value *Extract63 = Builder.CreateLShr(Shr18, Builder.getIntN(BitWidth, 32));
 436   Value *ExtractT64 = nullptr;
 437   if (FloatWidth > 80)
 438     ExtractT64 = Builder.CreateTrunc(Sub2, Builder.getInt64Ty());
 439   else
 440     ExtractT64 = Builder.CreateTrunc(Extract63, Builder.getInt32Ty());
 441   Builder.CreateCondBr(PosOrNeg, IfEnd26, IfThen20);
 442
 443   // if.then20
 444   Builder.SetInsertPoint(IfThen20);
 445   Value *Shr21 = nullptr;
 446   if (IsSigned)
 447     Shr21 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 3));
 448   else
 449     Shr21 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 3));
 450   Value *ExtractT = Builder.CreateTrunc(Shr21, Builder.getIntNTy(FloatWidth));
 451   Value *Extract = Builder.CreateLShr(Shr21, Builder.getIntN(BitWidth, 32));
 452   Value *ExtractT62 = nullptr;
 453   if (FloatWidth > 80)
 454     ExtractT62 = Builder.CreateTrunc(Sub1, Builder.getIntNTy(64));
 455   else
 456     ExtractT62 = Builder.CreateTrunc(Extract, Builder.getIntNTy(32));
 457   Builder.CreateBr(IfEnd26);
 458
 459   // if.else:
 460   Builder.SetInsertPoint(IfElse);
 461   Value *Sub24 = Builder.CreateAdd(
 462       FloatWidth == 128 ? Call : Cast,
 463       ConstantInt::getSigned(Builder.getIntNTy(BitWidthNew),
 464                              -(BitWidth - FPMantissaWidth - 1)));
 465   Value *ShProm25 = Builder.CreateZExt(Sub24, IntTy);
 466   Value *Shl26 = Builder.CreateShl(IsSigned ? Sub : IntVal,
 467                                    FloatWidth == 128 ? Sub24 : ShProm25);
 468   Value *ExtractT61 = Builder.CreateTrunc(Shl26, Builder.getIntNTy(FloatWidth));
 469   Value *Extract65 = Builder.CreateLShr(Shl26, Builder.getIntN(BitWidth, 32));
 470   Value *ExtractT66 = nullptr;
 471   if (FloatWidth > 80)
 472     ExtractT66 = Builder.CreateTrunc(Sub2, Builder.getIntNTy(64));
 473   else
 474     ExtractT66 = Builder.CreateTrunc(Extract65, Builder.getInt32Ty());
 475   Builder.CreateBr(IfEnd26);
 476
 477   // if.end26:
 478   Builder.SetInsertPoint(IfEnd26);
 479   PHINode *AAddr1Off0 = Builder.CreatePHI(Builder.getIntNTy(FloatWidth), 3);
 480   AAddr1Off0->addIncoming(ExtractT, IfThen20);
 481   AAddr1Off0->addIncoming(ExtractT60, SwEpilog);
 482   AAddr1Off0->addIncoming(ExtractT61, IfElse);
 483   PHINode *AAddr1Off32 = nullptr;
 484   if (FloatWidth > 32) {
 485     AAddr1Off32 =
 486         Builder.CreatePHI(Builder.getIntNTy(FloatWidth > 80 ? 64 : 32), 3);
 487     AAddr1Off32->addIncoming(ExtractT62, IfThen20);
 488     AAddr1Off32->addIncoming(ExtractT64, SwEpilog);
 489     AAddr1Off32->addIncoming(ExtractT66, IfElse);
 490   }
 491   PHINode *E0 = nullptr;
 492   if (FloatWidth <= 80) {
 493     E0 = Builder.CreatePHI(Builder.getIntNTy(BitWidthNew), 3);
 494     E0->addIncoming(Sub1, IfThen20);
 495     E0->addIncoming(Sub2, SwEpilog);
 496     E0->addIncoming(Sub2, IfElse);
 497   }
 498   Value *And29 = nullptr;
 499   if (FloatWidth > 80) {
 500     Value *Temp2 = Builder.CreateShl(Builder.getIntN(BitWidth, 1),
 501                                      Builder.getIntN(BitWidth, 63));
 502     And29 = Builder.CreateAnd(Shr, Temp2, "and29");
 503   } else {
 504     Value *Conv28 = Builder.CreateTrunc(Shr, Builder.getIntNTy(32));
 505     And29 = Builder.CreateAnd(
 506         Conv28, ConstantInt::getSigned(Builder.getIntNTy(32), 0x80000000));
 507   }
 508   unsigned TempMod = FPMantissaWidth % 32;
 509   Value *And34 = nullptr;
 510   Value *Shl30 = nullptr;
 511   if (FloatWidth > 80) {
 512     TempMod += 32;
 513     Value *Add = Builder.CreateShl(AAddr1Off32, Builder.getIntN(64, TempMod));
 514     Shl30 = Builder.CreateAdd(
 515         Add,
 516         Builder.getIntN(64, ((1ull << (62ull - TempMod)) - 1ull) << TempMod));
 517     And34 = Builder.CreateZExt(Shl30, Builder.getIntNTy(128));
 518   } else {
 519     Value *Add = Builder.CreateShl(E0, Builder.getIntN(32, TempMod));
 520     Shl30 = Builder.CreateAdd(
 521         Add, Builder.getIntN(32, ((1 << (30 - TempMod)) - 1) << TempMod));
 522     And34 = Builder.CreateAnd(FloatWidth > 32 ? AAddr1Off32 : AAddr1Off0,
 523                               Builder.getIntN(32, (1 << TempMod) - 1));
 524   }
 525   Value *Or35 = nullptr;
 526   if (FloatWidth > 80) {
 527     Value *And29Trunc = Builder.CreateTrunc(And29, Builder.getIntNTy(128));
 528     Value *Or31 = Builder.CreateOr(And29Trunc, And34);
 529     Value *Or34 = Builder.CreateShl(Or31, Builder.getIntN(128, 64));
 530     Value *Temp3 = Builder.CreateShl(Builder.getIntN(128, 1),
 531                                      Builder.getIntN(128, FPMantissaWidth));
 532     Value *Temp4 = Builder.CreateSub(Temp3, Builder.getIntN(128, 1));
 533     Value *A6 = Builder.CreateAnd(AAddr1Off0, Temp4);
 534     Or35 = Builder.CreateOr(Or34, A6);
 535   } else {
 536     Value *Or31 = Builder.CreateOr(And34, And29);
 537     Or35 = Builder.CreateOr(IsSigned ? Or31 : And34, Shl30);
 538   }
 539   Value *A4 = nullptr;
 540   if (IToFP->getType()->isDoubleTy()) {
 541     Value *ZExt1 = Builder.CreateZExt(Or35, Builder.getIntNTy(FloatWidth));
 542     Value *Shl1 = Builder.CreateShl(ZExt1, Builder.getIntN(FloatWidth, 32));
 543     Value *And1 =
 544         Builder.CreateAnd(AAddr1Off0, Builder.getIntN(FloatWidth, 0xFFFFFFFF));
 545     Value *Or1 = Builder.CreateOr(Shl1, And1);
 546     A4 = Builder.CreateBitCast(Or1, IToFP->getType());
 547   } else if (IToFP->getType()->isX86_FP80Ty()) {
 548     Value *A40 =
 549         Builder.CreateBitCast(Or35, Type::getFP128Ty(Builder.getContext()));
 550     A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
 551   } else if (IToFP->getType()->isHalfTy() || IToFP->getType()->isBFloatTy()) {
 552     // Deal with "half" situation. This is a workaround since we don't have
 553     // floattihf.c currently as referring.
 554     Value *A40 =
 555         Builder.CreateBitCast(Or35, Type::getFloatTy(Builder.getContext()));
 556     A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
 557   } else // float type
 558     A4 = Builder.CreateBitCast(Or35, IToFP->getType());
 559   Builder.CreateBr(End);
 560
 561   // return:
 562   Builder.SetInsertPoint(End, End->begin());
 563   PHINode *Retval0 = Builder.CreatePHI(IToFP->getType(), 2);
 564   Retval0->addIncoming(A4, IfEnd26);
 565   Retval0->addIncoming(ConstantFP::getZero(IToFP->getType(), false), Entry);
 566
 567   IToFP->replaceAllUsesWith(Retval0);
 568   IToFP->dropAllReferences();
 569   IToFP->eraseFromParent();
 570 }
 571
 572 static void scalarize(Instruction *I, SmallVectorImpl<Instruction *> &Replace) {
 573   VectorType *VTy = cast<FixedVectorType>(I->getType());
 574
 575   IRBuilder<> Builder(I);
 576
 577   unsigned NumElements = VTy->getElementCount().getFixedValue();
 578   Value *Result = PoisonValue::get(VTy);
 579   for (unsigned Idx = 0; Idx < NumElements; ++Idx) {
 580     Value *Ext = Builder.CreateExtractElement(I->getOperand(0), Idx);
 581     Value *Cast = Builder.CreateCast(cast<CastInst>(I)->getOpcode(), Ext,
 582                                      I->getType()->getScalarType());
 583     Result = Builder.CreateInsertElement(Result, Cast, Idx);
 584     if (isa<Instruction>(Cast))
 585       Replace.push_back(cast<Instruction>(Cast));
 586   }
 587   I->replaceAllUsesWith(Result);
 588   I->dropAllReferences();
 589   I->eraseFromParent();
 590 }
 591
 592 static bool runImpl(Function &F, const TargetLowering &TLI) {
 593   SmallVector<Instruction *, 4> Replace;
 594   SmallVector<Instruction *, 4> ReplaceVector;
 595   bool Modified = false;
 596
 597   unsigned MaxLegalFpConvertBitWidth =
 598       TLI.getMaxLargeFPConvertBitWidthSupported();
 599   if (ExpandFpConvertBits != llvm::IntegerType::MAX_INT_BITS)
 600     MaxLegalFpConvertBitWidth = ExpandFpConvertBits;
 601
 602   if (MaxLegalFpConvertBitWidth >= llvm::IntegerType::MAX_INT_BITS)
 603     return false;
 604
 605   for (auto &I : instructions(F)) {
 606     switch (I.getOpcode()) {
 607     case Instruction::FPToUI:
 608     case Instruction::FPToSI: {
 609       // TODO: This pass doesn't handle scalable vectors.
 610       if (I.getOperand(0)->getType()->isScalableTy())
 611         continue;
 612
 613       auto *IntTy = cast<IntegerType>(I.getType()->getScalarType());
 614       if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
 615         continue;
 616
 617       if (I.getOperand(0)->getType()->isVectorTy())
 618         ReplaceVector.push_back(&I);
 619       else
 620         Replace.push_back(&I);
 621       Modified = true;
 622       break;
 623     }
 624     case Instruction::UIToFP:
 625     case Instruction::SIToFP: {
 626       // TODO: This pass doesn't handle scalable vectors.
 627       if (I.getOperand(0)->getType()->isScalableTy())
 628         continue;
 629
 630       auto *IntTy =
 631           cast<IntegerType>(I.getOperand(0)->getType()->getScalarType());
 632       if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
 633         continue;
 634
 635       if (I.getOperand(0)->getType()->isVectorTy())
 636         ReplaceVector.push_back(&I);
 637       else
 638         Replace.push_back(&I);
 639       Modified = true;
 640       break;
 641     }
 642     default:
 643       break;
 644     }
 645   }
 646
 647   while (!ReplaceVector.empty()) {
 648     Instruction *I = ReplaceVector.pop_back_val();
 649     scalarize(I, Replace);
 650   }
 651
 652   if (Replace.empty())
 653     return false;
 654
 655   while (!Replace.empty()) {
 656     Instruction *I = Replace.pop_back_val();
 657     if (I->getOpcode() == Instruction::FPToUI ||
 658         I->getOpcode() == Instruction::FPToSI) {
 659       expandFPToI(I);
 660     } else {
 661       expandIToFP(I);
 662     }
 663   }
 664
 665   return Modified;
 666 }
 667
 668 namespace {
 669 class ExpandLargeFpConvertLegacyPass : public FunctionPass {
 670 public:
 671   static char ID;
 672
 673   ExpandLargeFpConvertLegacyPass() : FunctionPass(ID) {
 674     initializeExpandLargeFpConvertLegacyPassPass(
 675         *PassRegistry::getPassRegistry());
 676   }
 677
 678   bool runOnFunction(Function &F) override {
 679     auto *TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
 680     auto *TLI = TM->getSubtargetImpl(F)->getTargetLowering();
 681     return runImpl(F, *TLI);
 682   }
 683
 684   void getAnalysisUsage(AnalysisUsage &AU) const override {
 685     AU.addRequired<TargetPassConfig>();
 686     AU.addPreserved<AAResultsWrapperPass>();
 687     AU.addPreserved<GlobalsAAWrapperPass>();
 688   }
 689 };
 690 } // namespace
 691
 692 PreservedAnalyses ExpandLargeFpConvertPass::run(Function &F,
 693                                                 FunctionAnalysisManager &FAM) {
 694   const TargetSubtargetInfo *STI = TM->getSubtargetImpl(F);
 695   return runImpl(F, *STI->getTargetLowering()) ? PreservedAnalyses::none()
 696                                                : PreservedAnalyses::all();
 697 }
 698
 699 char ExpandLargeFpConvertLegacyPass::ID = 0;
 700 INITIALIZE_PASS_BEGIN(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
 701                       "Expand large fp convert", false, false)
 702 INITIALIZE_PASS_END(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
 703                     "Expand large fp convert", false, false)
 704
 705 FunctionPass *llvm::createExpandLargeFpConvertPass() {
 706   return new ExpandLargeFpConvertLegacyPass();
 707 }