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| author | Justin Lebar <jlebar@google.com> | 2017-01-18 00:08:44 +0000 |
|---|---|---|
| committer | Justin Lebar <jlebar@google.com> | 2017-01-18 00:08:44 +0000 |
| commit | 7dc3d6c3415db5f30d4acafc725a50debdac3bf7 (patch) | |
| tree | 64dd88414a42c2fac71f9f174a1e8ff50f68dbde /llvm/lib/Target/NVPTX | |
| parent | 1091a9f56670e4681acf1d7a7e92b22e7ac3dddb (diff) | |
| download | bcm5719-llvm-7dc3d6c3415db5f30d4acafc725a50debdac3bf7.tar.gz bcm5719-llvm-7dc3d6c3415db5f30d4acafc725a50debdac3bf7.zip | |
[NVPTX] Lower integer absolute value idiom to abs instruction.
Summary: Previously we lowered it literally, to shifts and xors.
Reviewers: tra
Subscribers: jholewinski, llvm-commits
Differential Revision: https://reviews.llvm.org/D28722
llvm-svn: 292303
Diffstat (limited to 'llvm/lib/Target/NVPTX')
| -rw-r--r-- | llvm/lib/Target/NVPTX/NVPTXInstrInfo.td | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/llvm/lib/Target/NVPTX/NVPTXInstrInfo.td b/llvm/lib/Target/NVPTX/NVPTXInstrInfo.td index 179830817ed..ac7b7e0b9f4 100644 --- a/llvm/lib/Target/NVPTX/NVPTXInstrInfo.td +++ b/llvm/lib/Target/NVPTX/NVPTXInstrInfo.td @@ -516,6 +516,18 @@ defm UDIV : I3<"div.u", udiv>; defm SREM : I3<"rem.s", srem>; defm UREM : I3<"rem.u", urem>; +// Integer absolute value. NumBits should be one minus the bit width of RC. +// This idiom implements the algorithm at +// http://graphics.stanford.edu/~seander/bithacks.html#IntegerAbs. +multiclass ABS<RegisterClass RC, int NumBits, string SizeName> { + def : NVPTXInst<(outs RC:$dst), (ins RC:$a), + !strconcat("abs", SizeName, " \t$dst, $a;"), + [(set RC:$dst, (xor (add (sra RC:$a, (i32 NumBits)), RC:$a), + (sra RC:$a, (i32 NumBits))))]>; +} +defm ABS_16 : ABS<Int16Regs, 15, ".s16">; +defm ABS_32 : ABS<Int32Regs, 31, ".s32">; +defm ABS_64 : ABS<Int64Regs, 63, ".s64">; // // Wide multiplication |
