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The VTBL (and VTBX) instructions are rather permissive concerning the masks they 

accept. If a value in the mask is out of range, it uses the value 0, for VTBL,
or leaves the value unchanged, for VTBX.

llvm-svn: 127700
This commit is contained in:
Bill Wendling 2011-03-15 21:15:20 +00:00
parent e800838170
commit 865f8b592a
1 changed files with 8 additions and 0 deletions
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8
llvm/lib/Target/ARM/ARMISelLowering.cpp
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@ -3541,6 +3541,13 @@ static bool isVREVMask(const SmallVectorImpl<int> &M, EVT VT,
return true;
}
static bool isVTBLMask(const SmallVectorImpl<int> &M, EVT VT) {
// We can handle <8 x i8> vector shuffles. If the index in the mask is out of
// range, then 0 is placed into the resulting vector. So pretty much any mask
// of 8 elements can work here.
return VT == MVT::v8i8 && M.size() == 8;
}
static bool isVTRNMask(const SmallVectorImpl<int> &M, EVT VT,
unsigned &WhichResult) {
unsigned EltSz = VT.getVectorElementType().getSizeInBits();
@ -3980,6 +3987,7 @@ ARMTargetLowering::isShuffleMaskLegal(const SmallVectorImpl<int> &M,
isVREVMask(M, VT, 32) ||
isVREVMask(M, VT, 16) ||
isVEXTMask(M, VT, ReverseVEXT, Imm) ||
isVTBLMask(M, VT) ||
isVTRNMask(M, VT, WhichResult) ||
isVUZPMask(M, VT, WhichResult) ||
isVZIPMask(M, VT, WhichResult) ||