From ecc091f771a338fd2d92036f8883c9f49ac3f608 Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Fri, 4 Oct 2024 16:23:32 -0700 Subject: [PATCH] [APInt] Slightly simplify APInt::ashrSlowCase. NFC Use an arithmetic shift for the last word copy when BitShift!=0. This avoids an explicit sign extend after the shift. --- llvm/lib/Support/APInt.cpp | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp index 2348a4c9b795e..23e365f16d8fe 100644 --- a/llvm/lib/Support/APInt.cpp +++ b/llvm/lib/Support/APInt.cpp @@ -1055,11 +1055,10 @@ void APInt::ashrSlowCase(unsigned ShiftAmt) { U.pVal[i] = (U.pVal[i + WordShift] >> BitShift) | (U.pVal[i + WordShift + 1] << (APINT_BITS_PER_WORD - BitShift)); - // Handle the last word which has no high bits to copy. - U.pVal[WordsToMove - 1] = U.pVal[WordShift + WordsToMove - 1] >> BitShift; - // Sign extend one more time. + // Handle the last word which has no high bits to copy. Use an arithmetic + // shift to preserve the sign bit. U.pVal[WordsToMove - 1] = - SignExtend64(U.pVal[WordsToMove - 1], APINT_BITS_PER_WORD - BitShift); + (int64_t)U.pVal[WordShift + WordsToMove - 1] >> BitShift; } }