[Git][ghc/ghc][master] Add fused multiply-add instructions

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
87eebf98 by sheaf at 2023-05-11T11:55:22-04:00
Add fused multiply-add instructions

This patch adds eight new primops that fuse a multiplication and an
addition or subtraction:

  - `{fmadd,fmsub,fnmadd,fnmsub}{Float,Double}#`

fmadd x y z is x * y + z, computed with a single rounding step.

This patch implements code generation for these primops in the following
backends:

  - X86, AArch64 and PowerPC NCG,
  - LLVM
  - C

WASM uses the C implementation. The primops are unsupported in the
JavaScript backend.

The following constant folding rules are also provided:

  - compute a * b + c when a, b, c are all literals,
  - x * y + 0 ==> x * y,
  - ±1 * y + z ==> z ± y and x * ±1 + z ==> z ± x.

NB: the constant folding rules incorrectly handle signed zero.
This is a known limitation with GHC's floating-point constant folding
rules (#21227), which we hope to resolve in the future.

- - - - -


30 changed files:

- compiler/GHC/Builtin/primops.txt.pp
- compiler/GHC/Cmm/MachOp.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
- compiler/GHC/CmmToAsm/AArch64/Instr.hs
- compiler/GHC/CmmToAsm/AArch64/Ppr.hs
- compiler/GHC/CmmToAsm/PPC/CodeGen.hs
- compiler/GHC/CmmToAsm/PPC/Instr.hs
- compiler/GHC/CmmToAsm/PPC/Ppr.hs
- compiler/GHC/CmmToAsm/Wasm/FromCmm.hs
- compiler/GHC/CmmToAsm/X86/CodeGen.hs
- compiler/GHC/CmmToAsm/X86/Instr.hs
- compiler/GHC/CmmToAsm/X86/Ppr.hs
- compiler/GHC/CmmToC.hs
- compiler/GHC/CmmToLlvm/CodeGen.hs
- compiler/GHC/Core/Opt/ConstantFold.hs
- compiler/GHC/Driver/Config/StgToCmm.hs
- compiler/GHC/Driver/Pipeline/Execute.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Llvm/Ppr.hs
- compiler/GHC/Llvm/Syntax.hs
- compiler/GHC/Llvm/Types.hs
- compiler/GHC/StgToCmm/Config.hs
- compiler/GHC/StgToCmm/Prim.hs
- compiler/GHC/StgToJS/Prim.hs
- compiler/GHC/SysTools/Cpp.hs
- docs/users_guide/9.8.1-notes.rst
- docs/users_guide/using.rst
- libraries/ghc-prim/changelog.md
- rts/RtsSymbols.c


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/87eebf98cb485f7c9175330051736e147ade9848

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/87eebf98cb485f7c9175330051736e147ade9848
You're receiving this email because of your account on gitlab.haskell.org.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-commits/attachments/20230511/04664583/attachment.html>