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[DXIL] Add log, log2, and log10 intrinsic Lowering #86192

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Tracked by #30
farzonl opened this issue Mar 21, 2024 · 0 comments · Fixed by #86569
Closed
Tracked by #30

[DXIL] Add log, log2, and log10 intrinsic Lowering #86192

farzonl opened this issue Mar 21, 2024 · 0 comments · Fixed by #86569
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farzonl commented Mar 21, 2024

Needs to cover the float and half case for all three: https://godbolt.org/z/64fzEq3nd

This is a perfect candidate for instruction expansion:

  • log2
    • This is the simplest case just call unary dxilop 23
  • log
    • Call log2 DXIL op (ie 23)
    • Create a ln2 const value
      • M_LN2_F 0.693147180559945309417232121458176568f
      • M_LN2_H 0.693147180559945309417232121458176568h
    • Floating point multiply the value of M_LN2 with the return value of log2
    • Reference implementation
  • log10
    • Define M_LN10
      • M_LN10_F 2.30258509299404568401799145468436421f
      • M_LN10_H 2.30258509299404568401799145468436421h
    • Call log2 DXIL op (ie 23)
    • Create a log2_10Const = M_LN2 / M_LN10 const value
  • Floating point multiply the value of log2_10Const with the return value of log2
  • Reference implementation
@farzonl farzonl self-assigned this Mar 25, 2024
farzonl added a commit to farzonl/llvm-project that referenced this issue Mar 25, 2024
@farzonl
[DXIL] Implement log intrinsic Lowering
824939e 
Completes llvm#86192
`DXIL.td` - add log2 to dxilop lowering
`DXILIntrinsicExpansion.cpp` - add log and log10 to log2 expansions
@farzonl farzonl mentioned this issue Mar 25, 2024
Merged
@farzonl farzonl moved this to Active in HLSL Support Mar 25, 2024
@farzonl farzonl linked a pull request Mar 25, 2024 that will close this issue
[DXIL] Implement log intrinsic Lowering #86569
Merged
farzonl added a commit to farzonl/llvm-project that referenced this issue Mar 26, 2024
@farzonl
[DXIL] Implement log intrinsic Lowering
8665e4e 
Completes llvm#86192
`DXIL.td` - add log2 to dxilop lowering
`DXILIntrinsicExpansion.cpp` - add log and log10 to log2 expansions
farzonl added a commit that referenced this issue Mar 26, 2024
@farzonl
[DXIL] Implement log intrinsic Lowering (#86569)
5cf1e2e 
Completes #86192
`DXIL.td` - add log2 to dxilop lowering
`DXILIntrinsicExpansion.cpp` - add log and log10 to log2 expansions
@github-project-automation github-project-automation bot moved this from Active to Done in HLSL Support Mar 26, 2024
@farzonl farzonl mentioned this issue Aug 7, 2024
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[DXIL] Implement log intrinsic Lowering farzonl/llvm-project
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