Changes in directory llvm/lib/Support:
APInt.cpp updated: 1.76 -> 1.77 --- Log message: Implement a getBitsNeeded method to determine how many bits are needed to represent a string in binary form by an APInt. --- Diffs of the changes: (+37 -0) APInt.cpp | 37 +++++++++++++++++++++++++++++++++++++ 1 files changed, 37 insertions(+) Index: llvm/lib/Support/APInt.cpp diff -u llvm/lib/Support/APInt.cpp:1.76 llvm/lib/Support/APInt.cpp:1.77 --- llvm/lib/Support/APInt.cpp:1.76 Wed Apr 11 08:00:04 2007 +++ llvm/lib/Support/APInt.cpp Fri Apr 13 14:19:07 2007 @@ -659,6 +659,43 @@ return *this; } +uint32_t APInt::getBitsNeeded(const char* str, uint32_t slen, uint8_t radix) { + assert(str != 0 && "Invalid value string"); + assert(slen > 0 && "Invalid string length"); + + // Each computation below needs to know if its negative + uint32_t isNegative = str[0] == '-'; + if (isNegative) { + slen--; + str++; + } + // For radixes of power-of-two values, the bits required is accurately and + // easily computed + if (radix == 2) + return slen + isNegative; + if (radix == 8) + return slen * 3 + isNegative; + if (radix == 16) + return slen * 4 + isNegative; + + // Otherwise it must be radix == 10, the hard case + assert(radix == 10 && "Invalid radix"); + + // This is grossly inefficient but accurate. We could probably do something + // with a computation of roughly slen*64/20 and then adjust by the value of + // the first few digits. But, I'm not sure how accurate that could be. + + // Compute a sufficient number of bits that is always large enough but might + // be too large. This avoids the assertion in the constructor. + uint32_t sufficient = slen*64/18; + + // Convert to the actual binary value. + APInt tmp(sufficient, str, slen, radix); + + // Compute how many bits are required. + return isNegative + tmp.logBase2(); +} + uint64_t APInt::getHashValue() const { // Put the bit width into the low order bits. uint64_t hash = BitWidth; _______________________________________________ llvm-commits mailing list [EMAIL PROTECTED] http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits