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      1 //===---- llvm/Support/Discriminator.h -- Discriminator Utils ---*- C++ -*-===//
      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 defines the constants and utility functions for discriminators.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #ifndef LLVM_SUPPORT_DISCRIMINATOR_H
     14 #define LLVM_SUPPORT_DISCRIMINATOR_H
     15 
     16 // Utility functions for encoding / decoding discriminators.
     17 /// With a given unsigned int \p U, use up to 13 bits to represent it.
     18 /// old_bit 1~5  --> new_bit 1~5
     19 /// old_bit 6~12 --> new_bit 7~13
     20 /// new_bit_6 is 0 if higher bits (7~13) are all 0
     21 static inline unsigned getPrefixEncodingFromUnsigned(unsigned U) {
     22   U &= 0xfff;
     23   return U > 0x1f ? (((U & 0xfe0) << 1) | (U & 0x1f) | 0x20) : U;
     24 }
     25 
     26 /// Reverse transformation as getPrefixEncodingFromUnsigned.
     27 static inline unsigned getUnsignedFromPrefixEncoding(unsigned U) {
     28   if (U & 1)
     29     return 0;
     30   U >>= 1;
     31   return (U & 0x20) ? (((U >> 1) & 0xfe0) | (U & 0x1f)) : (U & 0x1f);
     32 }
     33 
     34 /// Returns the next component stored in discriminator.
     35 static inline unsigned getNextComponentInDiscriminator(unsigned D) {
     36   if ((D & 1) == 0)
     37     return D >> ((D & 0x40) ? 14 : 7);
     38   else
     39     return D >> 1;
     40 }
     41 
     42 static inline unsigned encodeComponent(unsigned C) {
     43   return (C == 0) ? 1U : (getPrefixEncodingFromUnsigned(C) << 1);
     44 }
     45 
     46 static inline unsigned encodingBits(unsigned C) {
     47   return (C == 0) ? 1 : (C > 0x1f ? 14 : 7);
     48 }
     49 
     50 // Some constants used in FS Discriminators.
     51 #define BASE_DIS_BIT_BEG 0
     52 #define BASE_DIS_BIT_END 7
     53 
     54 #define PASS_1_DIS_BIT_BEG 8
     55 #define PASS_1_DIS_BIT_END 13
     56 
     57 #define PASS_2_DIS_BIT_BEG 14
     58 #define PASS_2_DIS_BIT_END 19
     59 
     60 #define PASS_3_DIS_BIT_BEG 20
     61 #define PASS_3_DIS_BIT_END 25
     62 
     63 #define PASS_LAST_DIS_BIT_BEG 26
     64 #define PASS_LAST_DIS_BIT_END 31
     65 
     66 // Set bits range [0 .. n] to 1. Used in FS Discriminators.
     67 static inline unsigned getN1Bits(int N) {
     68   if (N >= 31)
     69     return 0xFFFFFFFF;
     70   return (1 << (N + 1)) - 1;
     71 }
     72 
     73 #endif /* LLVM_SUPPORT_DISCRIMINATOR_H */
     74