From 8da7d65b8350d0f47f47ab496328d9068ac6764d Mon Sep 17 00:00:00 2001 From: Reid Spencer Date: Sat, 24 Mar 2007 23:05:35 +0000 Subject: [PATCH] Implement the getHighBitsSet and getLowBitsSet functions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35308 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/ADT/APInt.h | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h index 90564ef3f8b..31fac9608f8 100644 --- a/include/llvm/ADT/APInt.h +++ b/include/llvm/ADT/APInt.h @@ -346,13 +346,27 @@ public: /// @param numBits the bitwidth of the result /// @param hiBitsSet the number of high-order bits set in the result. /// @brief Get a value with high bits set - static APInt getHighBitsSet(uint32_t numBits, uint32_t hiBitsSet); + static APInt getHighBitsSet(uint32_t numBits, uint32_t hiBitsSet) { + assert(hiBitsSet <= numBits && "Too many bits to set!"); + uint32_t mvBits = numBits - hiBitsSet; + // For small values, return quickly + if (numBits <= APINT_BITS_PER_WORD) + return APInt(numBits, ((1ULL << hiBitsSet) - 1) << mvBits); + APInt Result(numBits, 1); + return (APInt(numBits, 1).shl(hiBitsSet) - APInt(numBits, 1)).shl(mvBits); + } /// Constructs an APInt value that has the bottom loBitsSet bits set. /// @param numBits the bitwidth of the result /// @param loBitsSet the number of low-order bits set in the result. /// @brief Get a value with low bits set - static APInt getLowBitsSet(uint32_t numBits, uint32_t loBitsSet); + static APInt getLowBitsSet(uint32_t numBits, uint32_t loBitsSet) { + assert(loBitsSet <= numBits && "Too many bits to set!"); + // For small values, return quickly + if (numBits <= APINT_BITS_PER_WORD) + return APInt(numBits, (1ULL << loBitsSet) - 1ULL); + return APInt(numBits, 1).shl(loBitsSet) - APInt(numBits, 1); + } /// The hash value is computed as the sum of the words and the bit width. /// @returns A hash value computed from the sum of the APInt words.