Files
llvm-6502/lib/Target/X86/Utils/X86ShuffleDecode.h
Chandler Carruth 1029c7003f [x86] Largely complete the use of PSHUFB in the new vector shuffle
lowering with a small addition to it and adding PSHUFB combining.

There is one obvious place in the new vector shuffle lowering where we
should form PSHUFBs directly: when without them we will unpack a vector
of i8s across two different registers and do a potentially 4-way blend
as i16s only to re-pack them into i8s afterward. This is the crazy
expensive fallback path for i8 shuffles and we can just directly use
pshufb here as it will always be cheaper (the unpack and pack are
two instructions so even a single shuffle between them hits our
three instruction limit for forming PSHUFB).

However, this doesn't generate very good code in many cases, and it
leaves a bunch of common patterns not using PSHUFB. So this patch also
adds support for extracting a shuffle mask from PSHUFB in the X86
lowering code, and uses it to handle PSHUFBs in the recursive shuffle
combining. This allows us to combine through them, combine multiple ones
together, and generally produce sufficiently high quality code.

Extracting the PSHUFB mask is annoyingly complex because it could be
either pre-legalization or post-legalization. At least this doesn't have
to deal with re-materialized constants. =] I've added decode routines to
handle the different patterns that show up at this level and we dispatch
through them as appropriate.

The two primary test cases are updated. For the v16 test case there is
still a lot of room for improvement. Since I was going through it
systematically I left behind a bunch of FIXME lines that I'm hoping to
turn into ALL lines by the end of this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214628 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-02 10:39:15 +00:00

83 lines
3.0 KiB
C++

//===-- X86ShuffleDecode.h - X86 shuffle decode logic -----------*-C++-*---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Define several functions to decode x86 specific shuffle semantics into a
// generic vector mask.
//
//===----------------------------------------------------------------------===//
#ifndef X86_SHUFFLE_DECODE_H
#define X86_SHUFFLE_DECODE_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/ArrayRef.h"
//===----------------------------------------------------------------------===//
// Vector Mask Decoding
//===----------------------------------------------------------------------===//
namespace llvm {
class ConstantDataSequential;
class MVT;
enum {
SM_SentinelZero = -1
};
void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
// <3,1> or <6,7,2,3>
void DecodeMOVHLPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask);
// <0,2> or <0,1,4,5>
void DecodeMOVLHPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask);
void DecodePALIGNRMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
void DecodePSHUFMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
void DecodePSHUFHWMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
void DecodePSHUFLWMask(MVT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
/// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
/// the type of the vector allowing it to handle different datatypes and vector
/// widths.
void DecodeSHUFPMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
/// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
/// and punpckh*. VT indicates the type of the vector allowing it to handle
/// different datatypes and vector widths.
void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
/// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
/// and punpckl*. VT indicates the type of the vector allowing it to handle
/// different datatypes and vector widths.
void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
/// \brief Decode a PSHUFB mask from an IR-level vector constant.
void DecodePSHUFBMask(const ConstantDataSequential *C,
SmallVectorImpl<int> &ShuffleMask);
/// \brief Decode a PSHUFB mask from a raw array of constants such as from
/// BUILD_VECTOR.
void DecodePSHUFBMask(ArrayRef<uint64_t> RawMask,
SmallVectorImpl<int> &ShuffleMask);
void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask);
/// DecodeVPERMMask - this decodes the shuffle masks for VPERMQ/VPERMPD.
/// No VT provided since it only works on 256-bit, 4 element vectors.
void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
} // llvm namespace
#endif