Correctly byte-swap APInts with bit-widths greater than 64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145111 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index 3774c52..55cb433 100644
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -870,30 +870,43 @@
return Count;
}
+/// Perform a logical right-shift from Src to Dst, which must be equal or
+/// non-overlapping, of Words words, by Shift, which must be less than 64.
+static void lshrNear(uint64_t *Dst, uint64_t *Src, unsigned Words,
+ unsigned Shift) {
+ uint64_t Carry = 0;
+ for (int I = Words - 1; I >= 0; --I) {
+ uint64_t Tmp = Src[I];
+ Dst[I] = (Tmp >> Shift) | Carry;
+ Carry = Tmp << (64 - Shift);
+ }
+}
+
APInt APInt::byteSwap() const {
assert(BitWidth >= 16 && BitWidth % 16 == 0 && "Cannot byteswap!");
if (BitWidth == 16)
return APInt(BitWidth, ByteSwap_16(uint16_t(VAL)));
- else if (BitWidth == 32)
+ if (BitWidth == 32)
return APInt(BitWidth, ByteSwap_32(unsigned(VAL)));
- else if (BitWidth == 48) {
+ if (BitWidth == 48) {
unsigned Tmp1 = unsigned(VAL >> 16);
Tmp1 = ByteSwap_32(Tmp1);
uint16_t Tmp2 = uint16_t(VAL);
Tmp2 = ByteSwap_16(Tmp2);
return APInt(BitWidth, (uint64_t(Tmp2) << 32) | Tmp1);
- } else if (BitWidth == 64)
- return APInt(BitWidth, ByteSwap_64(VAL));
- else {
- APInt Result(BitWidth, 0);
- char *pByte = (char*)Result.pVal;
- for (unsigned i = 0; i < BitWidth / APINT_WORD_SIZE / 2; ++i) {
- char Tmp = pByte[i];
- pByte[i] = pByte[BitWidth / APINT_WORD_SIZE - 1 - i];
- pByte[BitWidth / APINT_WORD_SIZE - i - 1] = Tmp;
- }
- return Result;
}
+ if (BitWidth == 64)
+ return APInt(BitWidth, ByteSwap_64(VAL));
+
+ APInt Result(getNumWords() * APINT_BITS_PER_WORD, 0);
+ for (unsigned I = 0, N = getNumWords(); I != N; ++I)
+ Result.pVal[I] = ByteSwap_64(pVal[N - I - 1]);
+ if (Result.BitWidth != BitWidth) {
+ lshrNear(Result.pVal, Result.pVal, getNumWords(),
+ Result.BitWidth - BitWidth);
+ Result.BitWidth = BitWidth;
+ }
+ return Result;
}
APInt llvm::APIntOps::GreatestCommonDivisor(const APInt& API1,
@@ -1232,11 +1245,7 @@
// If we are shifting less than a word, compute the shift with a simple carry
if (shiftAmt < APINT_BITS_PER_WORD) {
- uint64_t carry = 0;
- for (int i = getNumWords()-1; i >= 0; --i) {
- val[i] = (pVal[i] >> shiftAmt) | carry;
- carry = pVal[i] << (APINT_BITS_PER_WORD - shiftAmt);
- }
+ lshrNear(val, pVal, getNumWords(), shiftAmt);
return APInt(val, BitWidth).clearUnusedBits();
}