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author | Lang Hames <lhames@gmail.com> | 2014-04-21 08:18:53 +0000 |
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committer | Lang Hames <lhames@gmail.com> | 2014-04-21 08:18:53 +0000 |
commit | f69bb5e43c1427d23800e4e678a7c2f2088f0c88 (patch) | |
tree | d0ff7069c0da0d27b4acfaf87c300004cb00711d /lib | |
parent | a21cd0433e7cde887b061ecac08c0de9f1cb8cb9 (diff) | |
download | llvm-f69bb5e43c1427d23800e4e678a7c2f2088f0c88.tar.gz llvm-f69bb5e43c1427d23800e4e678a7c2f2088f0c88.tar.bz2 llvm-f69bb5e43c1427d23800e4e678a7c2f2088f0c88.tar.xz |
[X86] ISEL (and X, <constant mask>) to BZHI when BMI2 is available.
Generating BZHI in the variable mask case, i.e. (and X, (sub (shl 1, N), 1)),
was already supported, but we were missing the constant-mask case. This patch
fixes that.
<rdar://problem/15480077>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206738 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Target/X86/X86ISelLowering.cpp | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 306fb7e199..d867414a98 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -18503,6 +18503,20 @@ static SDValue PerformAndCombine(SDNode *N, SelectionDAG &DAG, } } // BEXTR + // Check for BZHI with contiguous mask: (and X, 0x0..0f..f) + // This should be checked after BEXTR - when X is a shift, a BEXTR is + // preferrable. + if (Subtarget->hasBMI2()) { + if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N1)) { + uint64_t Mask = C->getZExtValue(); + if (isMask_64(Mask)) { + unsigned LZ = CountTrailingOnes_64(Mask); + return DAG.getNode(X86ISD::BZHI, DL, VT, N0, + DAG.getConstant(LZ, MVT::i8)); + } + } + } + return SDValue(); } |