[Clang] VectorExprEvaluator::VisitCallExpr / InterpretBuiltin - Allow GFNI intrinsics to be used in constexpr (llvm#169619)

Resolves llvm#169295

Author: chaitanyav

clang/include/clang/Basic/BuiltinsX86.td

@@ -408,39 +408,21 @@ let Features = "avx512f,vaes", Attributes = [NoThrow, Const, RequiredVectorWidth
   def aesdeclast512 : X86Builtin<"_Vector<8, long long int>(_Vector<8, long long int>, _Vector<8, long long int>)">;
 }
 
-let Features = "gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<128>] in {
+let Features = "gfni", Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<128>] in {
   def vgf2p8affineinvqb_v16qi : X86Builtin<"_Vector<16, char>(_Vector<16, char>, _Vector<16, char>, _Constant char)">;
-}
-
-let Features = "avx,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<256>] in {
-  def vgf2p8affineinvqb_v32qi : X86Builtin<"_Vector<32, char>(_Vector<32, char>, _Vector<32, char>, _Constant char)">;
-}
-
-let Features = "avx512f,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<512>] in {
-  def vgf2p8affineinvqb_v64qi : X86Builtin<"_Vector<64, char>(_Vector<64, char>, _Vector<64, char>, _Constant char)">;
-}
-
-let Features = "gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<128>] in {
   def vgf2p8affineqb_v16qi : X86Builtin<"_Vector<16, char>(_Vector<16, char>, _Vector<16, char>, _Constant char)">;
-}
-
-let Features = "avx,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<256>] in {
-  def vgf2p8affineqb_v32qi : X86Builtin<"_Vector<32, char>(_Vector<32, char>, _Vector<32, char>, _Constant char)">;
-}
-
-let Features = "avx512f,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<512>] in {
-  def vgf2p8affineqb_v64qi : X86Builtin<"_Vector<64, char>(_Vector<64, char>, _Vector<64, char>, _Constant char)">;
-}
-
-let Features = "gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<128>] in {
   def vgf2p8mulb_v16qi : X86Builtin<"_Vector<16, char>(_Vector<16, char>, _Vector<16, char>)">;
 }
 
-let Features = "avx,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<256>] in {
+let Features = "avx,gfni", Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<256>] in {
+  def vgf2p8affineinvqb_v32qi : X86Builtin<"_Vector<32, char>(_Vector<32, char>, _Vector<32, char>, _Constant char)">;
+  def vgf2p8affineqb_v32qi : X86Builtin<"_Vector<32, char>(_Vector<32, char>, _Vector<32, char>, _Constant char)">;
   def vgf2p8mulb_v32qi : X86Builtin<"_Vector<32, char>(_Vector<32, char>, _Vector<32, char>)">;
 }
 
-let Features = "avx512f,gfni", Attributes = [NoThrow, Const, RequiredVectorWidth<512>] in {
+let Features = "avx512f,gfni", Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<512>] in {
+  def vgf2p8affineinvqb_v64qi : X86Builtin<"_Vector<64, char>(_Vector<64, char>, _Vector<64, char>, _Constant char)">;
+  def vgf2p8affineqb_v64qi : X86Builtin<"_Vector<64, char>(_Vector<64, char>, _Vector<64, char>, _Constant char)">;
   def vgf2p8mulb_v64qi : X86Builtin<"_Vector<64, char>(_Vector<64, char>, _Vector<64, char>)">;
 }
 

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -3830,6 +3830,100 @@ static bool interp__builtin_ia32_multishiftqb(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp_builtin_ia32_gfni_affine(InterpState &S, CodePtr OpPC,
+                                            const CallExpr *Call,
+                                            bool Inverse) {
+  assert(Call->getNumArgs() == 3);
+  QualType XType = Call->getArg(0)->getType();
+  QualType AType = Call->getArg(1)->getType();
+  QualType ImmType = Call->getArg(2)->getType();
+  if (!XType->isVectorType() || !AType->isVectorType() ||
+      !ImmType->isIntegerType()) {
+    return false;
+  }
+
+  Pointer X, A;
+  APSInt Imm = popToAPSInt(S, Call->getArg(2));
+  A = S.Stk.pop<Pointer>();
+  X = S.Stk.pop<Pointer>();
+
+  const Pointer &Dst = S.Stk.peek<Pointer>();
+  const auto *XVecT = XType->castAs<VectorType>();
+  const auto *AVecT = AType->castAs<VectorType>();
+  assert(XVecT->getNumElements() == AVecT->getNumElements());
+  unsigned NumBytesInQWord = 8;
+  unsigned NumBytes = AVecT->getNumElements();
+  unsigned NumBitsInQWord = 64;
+  unsigned NumQWords = NumBytes / NumBytesInQWord;
+  unsigned NumBitsInByte = 8;
+  PrimType AElemT = *S.getContext().classify(AVecT->getElementType());
+
+  // computing A*X + Imm
+  for (unsigned QWordIdx = 0; QWordIdx != NumQWords; ++QWordIdx) {
+    // Extract the QWords from X, A
+    APInt XQWord(NumBitsInQWord, 0);
+    APInt AQWord(NumBitsInQWord, 0);
+    for (unsigned ByteIdx = 0; ByteIdx != NumBytesInQWord; ++ByteIdx) {
+      unsigned Idx = QWordIdx * NumBytesInQWord + ByteIdx;
+      uint8_t XByte;
+      uint8_t AByte;
+      INT_TYPE_SWITCH(AElemT, {
+        XByte = static_cast<uint8_t>(X.elem<T>(Idx));
+        AByte = static_cast<uint8_t>(A.elem<T>(Idx));
+      });
+
+      XQWord.insertBits(APInt(NumBitsInByte, XByte), ByteIdx * NumBitsInByte);
+      AQWord.insertBits(APInt(NumBitsInByte, AByte), ByteIdx * NumBitsInByte);
+    }
+
+    for (unsigned ByteIdx = 0; ByteIdx != NumBytesInQWord; ++ByteIdx) {
+      unsigned Idx = QWordIdx * NumBytesInQWord + ByteIdx;
+      uint8_t XByte =
+          XQWord.lshr(ByteIdx * NumBitsInByte).getLoBits(8).getZExtValue();
+      INT_TYPE_SWITCH(AElemT, {
+        Dst.elem<T>(Idx) = T::from(GFNIAffine(XByte, AQWord, Imm, Inverse));
+      });
+    }
+  }
+  Dst.initializeAllElements();
+  return true;
+}
+
+static bool interp__builtin_ia32_gfni_mul(InterpState &S, CodePtr OpPC,
+                                          const CallExpr *Call) {
+  assert(Call->getNumArgs() == 2);
+
+  QualType AType = Call->getArg(0)->getType();
+  QualType BType = Call->getArg(1)->getType();
+  if (!AType->isVectorType() || !BType->isVectorType()) {
+    return false;
+  }
+
+  Pointer A, B;
+  B = S.Stk.pop<Pointer>();
+  A = S.Stk.pop<Pointer>();
+
+  const Pointer &Dst = S.Stk.peek<Pointer>();
+  const auto *AVecT = AType->castAs<VectorType>();
+  const auto *BVecT = BType->castAs<VectorType>();
+  assert(AVecT->getNumElements() == BVecT->getNumElements());
+
+  PrimType AElemT = *S.getContext().classify(AVecT->getElementType());
+  unsigned NumBytes = A.getNumElems();
+
+  for (unsigned ByteIdx = 0; ByteIdx != NumBytes; ++ByteIdx) {
+    uint8_t AByte, BByte;
+    INT_TYPE_SWITCH(AElemT, {
+      AByte = static_cast<uint8_t>(A.elem<T>(ByteIdx));
+      BByte = static_cast<uint8_t>(B.elem<T>(ByteIdx));
+      Dst.elem<T>(ByteIdx) = T::from(GFNIMul(AByte, BByte));
+    });
+  }
+
+  Dst.initializeAllElements();
+  return true;
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
                       uint32_t BuiltinID) {
   if (!S.getASTContext().BuiltinInfo.isConstantEvaluated(BuiltinID))
@@ -4880,6 +4974,21 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
           return std::pair<unsigned, int>{SrcIdx,
                                           static_cast<int>(LaneOffset + Index)};
         });
+
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v64qi:
+    return interp_builtin_ia32_gfni_affine(S, OpPC, Call, true);
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v64qi:
+    return interp_builtin_ia32_gfni_affine(S, OpPC, Call, false);
+
+  case X86::BI__builtin_ia32_vgf2p8mulb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8mulb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8mulb_v64qi:
+    return interp__builtin_ia32_gfni_mul(S, OpPC, Call);
+
   case X86::BI__builtin_ia32_insertps128:
     return interp__builtin_ia32_shuffle_generic(
         S, OpPC, Call, [](unsigned DstIdx, unsigned Mask) {

clang/lib/AST/ExprConstShared.h

@@ -15,9 +15,12 @@
 #define LLVM_CLANG_LIB_AST_EXPRCONSTSHARED_H
 
 #include "clang/Basic/TypeTraits.h"
+#include <cstdint>
 
 namespace llvm {
 class APFloat;
+class APInt;
+class APSInt;
 }
 namespace clang {
 class QualType;
@@ -74,4 +77,9 @@ void HandleComplexComplexDiv(llvm::APFloat A, llvm::APFloat B, llvm::APFloat C,
 CharUnits GetAlignOfExpr(const ASTContext &Ctx, const Expr *E,
                          UnaryExprOrTypeTrait ExprKind);
 
+uint8_t GFNIMultiplicativeInverse(uint8_t Byte);
+uint8_t GFNIMul(uint8_t AByte, uint8_t BByte);
+uint8_t GFNIAffine(uint8_t XByte, const llvm::APInt &AQword,
+                   const llvm::APSInt &Imm, bool Inverse = false);
+
 #endif

clang/lib/AST/ExprConstant.cpp

@@ -13869,6 +13869,89 @@ bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
     return Success(R, E);
   }
 
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8affineinvqb_v64qi:
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8affineqb_v64qi: {
+
+    APValue X, A;
+    APSInt Imm;
+    if (!EvaluateAsRValue(Info, E->getArg(0), X) ||
+        !EvaluateAsRValue(Info, E->getArg(1), A) ||
+        !EvaluateInteger(E->getArg(2), Imm, Info))
+      return false;
+
+    assert(X.isVector() && A.isVector());
+    assert(X.getVectorLength() == A.getVectorLength());
+
+    bool IsInverse = false;
+    switch (E->getBuiltinCallee()) {
+    case X86::BI__builtin_ia32_vgf2p8affineinvqb_v16qi:
+    case X86::BI__builtin_ia32_vgf2p8affineinvqb_v32qi:
+    case X86::BI__builtin_ia32_vgf2p8affineinvqb_v64qi: {
+      IsInverse = true;
+    }
+    }
+
+    unsigned NumBitsInByte = 8;
+    unsigned NumBytesInQWord = 8;
+    unsigned NumBitsInQWord = 64;
+    unsigned NumBytes = A.getVectorLength();
+    unsigned NumQWords = NumBytes / NumBytesInQWord;
+    SmallVector<APValue, 64> Result;
+    Result.reserve(NumBytes);
+
+    // computing A*X + Imm
+    for (unsigned QWordIdx = 0; QWordIdx != NumQWords; ++QWordIdx) {
+      // Extract the QWords from X, A
+      APInt XQWord(NumBitsInQWord, 0);
+      APInt AQWord(NumBitsInQWord, 0);
+      for (unsigned ByteIdx = 0; ByteIdx != NumBytesInQWord; ++ByteIdx) {
+        unsigned Idx = QWordIdx * NumBytesInQWord + ByteIdx;
+        APInt XByte = X.getVectorElt(Idx).getInt();
+        APInt AByte = A.getVectorElt(Idx).getInt();
+        XQWord.insertBits(XByte, ByteIdx * NumBitsInByte);
+        AQWord.insertBits(AByte, ByteIdx * NumBitsInByte);
+      }
+
+      for (unsigned ByteIdx = 0; ByteIdx != NumBytesInQWord; ++ByteIdx) {
+        uint8_t XByte =
+            XQWord.lshr(ByteIdx * NumBitsInByte).getLoBits(8).getZExtValue();
+        Result.push_back(APValue(APSInt(
+            APInt(8, GFNIAffine(XByte, AQWord, Imm, IsInverse)), false)));
+      }
+    }
+
+    return Success(APValue(Result.data(), Result.size()), E);
+  }
+
+  case X86::BI__builtin_ia32_vgf2p8mulb_v16qi:
+  case X86::BI__builtin_ia32_vgf2p8mulb_v32qi:
+  case X86::BI__builtin_ia32_vgf2p8mulb_v64qi: {
+    APValue A, B;
+    if (!EvaluateAsRValue(Info, E->getArg(0), A) ||
+        !EvaluateAsRValue(Info, E->getArg(1), B))
+      return false;
+
+    assert(A.isVector() && B.isVector());
+    assert(A.getVectorLength() == B.getVectorLength());
+
+    unsigned NumBytes = A.getVectorLength();
+    SmallVector<APValue, 64> Result;
+    Result.reserve(NumBytes);
+
+    for (unsigned ByteIdx = 0; ByteIdx != NumBytes; ++ByteIdx) {
+      uint8_t AByte = A.getVectorElt(ByteIdx).getInt().getZExtValue();
+      uint8_t BByte = B.getVectorElt(ByteIdx).getInt().getZExtValue();
+      Result.push_back(APValue(
+          APSInt(APInt(8, GFNIMul(AByte, BByte)), /*IsUnsigned=*/false)));
+    }
+
+    return Success(APValue(Result.data(), Result.size()), E);
+  }
+
   case X86::BI__builtin_ia32_insertf32x4_256:
   case X86::BI__builtin_ia32_inserti32x4_256:
   case X86::BI__builtin_ia32_insertf64x2_256:
@@ -19478,6 +19561,88 @@ bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
   llvm_unreachable("unknown cast resulting in complex value");
 }
 
+uint8_t GFNIMultiplicativeInverse(uint8_t Byte) {
+  // Lookup Table for Multiplicative Inverse in GF(2^8)
+  const uint8_t GFInv[256] = {
+      0x00, 0x01, 0x8d, 0xf6, 0xcb, 0x52, 0x7b, 0xd1, 0xe8, 0x4f, 0x29, 0xc0,
+      0xb0, 0xe1, 0xe5, 0xc7, 0x74, 0xb4, 0xaa, 0x4b, 0x99, 0x2b, 0x60, 0x5f,
+      0x58, 0x3f, 0xfd, 0xcc, 0xff, 0x40, 0xee, 0xb2, 0x3a, 0x6e, 0x5a, 0xf1,
+      0x55, 0x4d, 0xa8, 0xc9, 0xc1, 0x0a, 0x98, 0x15, 0x30, 0x44, 0xa2, 0xc2,
+      0x2c, 0x45, 0x92, 0x6c, 0xf3, 0x39, 0x66, 0x42, 0xf2, 0x35, 0x20, 0x6f,
+      0x77, 0xbb, 0x59, 0x19, 0x1d, 0xfe, 0x37, 0x67, 0x2d, 0x31, 0xf5, 0x69,
+      0xa7, 0x64, 0xab, 0x13, 0x54, 0x25, 0xe9, 0x09, 0xed, 0x5c, 0x05, 0xca,
+      0x4c, 0x24, 0x87, 0xbf, 0x18, 0x3e, 0x22, 0xf0, 0x51, 0xec, 0x61, 0x17,
+      0x16, 0x5e, 0xaf, 0xd3, 0x49, 0xa6, 0x36, 0x43, 0xf4, 0x47, 0x91, 0xdf,
+      0x33, 0x93, 0x21, 0x3b, 0x79, 0xb7, 0x97, 0x85, 0x10, 0xb5, 0xba, 0x3c,
+      0xb6, 0x70, 0xd0, 0x06, 0xa1, 0xfa, 0x81, 0x82, 0x83, 0x7e, 0x7f, 0x80,
+      0x96, 0x73, 0xbe, 0x56, 0x9b, 0x9e, 0x95, 0xd9, 0xf7, 0x02, 0xb9, 0xa4,
+      0xde, 0x6a, 0x32, 0x6d, 0xd8, 0x8a, 0x84, 0x72, 0x2a, 0x14, 0x9f, 0x88,
+      0xf9, 0xdc, 0x89, 0x9a, 0xfb, 0x7c, 0x2e, 0xc3, 0x8f, 0xb8, 0x65, 0x48,
+      0x26, 0xc8, 0x12, 0x4a, 0xce, 0xe7, 0xd2, 0x62, 0x0c, 0xe0, 0x1f, 0xef,
+      0x11, 0x75, 0x78, 0x71, 0xa5, 0x8e, 0x76, 0x3d, 0xbd, 0xbc, 0x86, 0x57,
+      0x0b, 0x28, 0x2f, 0xa3, 0xda, 0xd4, 0xe4, 0x0f, 0xa9, 0x27, 0x53, 0x04,
+      0x1b, 0xfc, 0xac, 0xe6, 0x7a, 0x07, 0xae, 0x63, 0xc5, 0xdb, 0xe2, 0xea,
+      0x94, 0x8b, 0xc4, 0xd5, 0x9d, 0xf8, 0x90, 0x6b, 0xb1, 0x0d, 0xd6, 0xeb,
+      0xc6, 0x0e, 0xcf, 0xad, 0x08, 0x4e, 0xd7, 0xe3, 0x5d, 0x50, 0x1e, 0xb3,
+      0x5b, 0x23, 0x38, 0x34, 0x68, 0x46, 0x03, 0x8c, 0xdd, 0x9c, 0x7d, 0xa0,
+      0xcd, 0x1a, 0x41, 0x1c};
+
+  return GFInv[Byte];
+}
+
+uint8_t GFNIAffine(uint8_t XByte, const APInt &AQword, const APSInt &Imm,
+                   bool Inverse) {
+  unsigned NumBitsInByte = 8;
+  // Computing the affine transformation
+  uint8_t RetByte = 0;
+  for (uint32_t BitIdx = 0; BitIdx != NumBitsInByte; ++BitIdx) {
+    uint8_t AByte =
+        AQword.lshr((7 - static_cast<int32_t>(BitIdx)) * NumBitsInByte)
+            .getLoBits(8)
+            .getZExtValue();
+    uint8_t Product;
+    if (Inverse) {
+      Product = AByte & GFNIMultiplicativeInverse(XByte);
+    } else {
+      Product = AByte & XByte;
+    }
+    uint8_t Parity = 0;
+
+    // Dot product in GF(2) uses XOR instead of addition
+    for (unsigned PBitIdx = 0; PBitIdx != NumBitsInByte; ++PBitIdx) {
+      Parity = Parity ^ ((Product >> PBitIdx) & 0x1);
+    }
+
+    uint8_t Temp = Imm[BitIdx] ? 1 : 0;
+    RetByte |= (Temp ^ Parity) << BitIdx;
+  }
+  return RetByte;
+}
+
+uint8_t GFNIMul(uint8_t AByte, uint8_t BByte) {
+  // Multiplying two polynomials of degree 7
+  // Polynomial of degree 7
+  // x^7 + x^6 + x^5 + x^4 + x^3 + x^2 + x + 1
+  uint16_t TWord = 0;
+  unsigned NumBitsInByte = 8;
+  for (unsigned BitIdx = 0; BitIdx != NumBitsInByte; ++BitIdx) {
+    if ((BByte >> BitIdx) & 0x1) {
+      TWord = TWord ^ (AByte << BitIdx);
+    }
+  }
+
+  // When multiplying two polynomials of degree 7
+  // results in a polynomial of degree 14
+  // so the result has to be reduced to 7
+  // Reduction polynomial is x^8 + x^4 + x^3 + x + 1 i.e. 0x11B
+  for (int32_t BitIdx = 14; BitIdx > 7; --BitIdx) {
+    if ((TWord >> BitIdx) & 0x1) {
+      TWord = TWord ^ (0x11B << (BitIdx - 8));
+    }
+  }
+  return (TWord & 0xFF);
+}
+
 void HandleComplexComplexMul(APFloat A, APFloat B, APFloat C, APFloat D,
                              APFloat &ResR, APFloat &ResI) {
   // This is an implementation of complex multiplication according to the