Simon Peyton Jones pushed to branch wip/T27724 at Glasgow Haskell Compiler / GHC

Commits:

• 105054cd
  by Simon Peyton Jones at 2026-10-29T13:01:31+00:00

  Redesign the noinline magic
  
  Main idea:
  
  * When simplifying `noinline (f e1 e2)`, switch off inlining when simplifying `f`
  * Mechanism: see `simplOutId`, the `noinlineIdKey` case
  * If we see `noinline (f e1) e2`, the simplifier moves the `e2` inside; see the `splitContArgs` call.
    This is important so you can write `noinliine f e1 e2` and have it mean the same as `noinline (f e1 e2)`.
  * Now `f` sees all its arguments, henc:
    * Fixes #27724
    * Fixes #23911
  
  * Also fixes #27803 where we were not respecting `noinline` if the RHS
    was trivial
  
  See Note [noinlineId magic] for lots of specifics.  It's surprisingly tricky!
  
  For some reason a couple of perf tests allocate 1.2% less at compile time,n
  namely T29872 and T8095.  Geom mean decease of 0.1%
  
  Metric Decrease:
      T9872d
  

39 changed files:

• + changelog.d/T27724
• compiler/GHC/Builtin/WiredIn/Ids.hs
• compiler/GHC/Builtin/WiredIn/Prim.hs
• compiler/GHC/Builtin/WiredIn/Types/Box.hs
• compiler/GHC/Core/Opt/SetLevels.hs
• compiler/GHC/Core/Opt/Simplify/Env.hs
• compiler/GHC/Core/Opt/Simplify/Iteration.hs
• compiler/GHC/Core/Opt/Simplify/Utils.hs
• compiler/GHC/Core/TyCo/Make.hs
• compiler/GHC/Core/TyCo/Rep.hs
• compiler/GHC/Core/Type.hs
• compiler/GHC/CoreToIface.hs
• compiler/GHC/CoreToStg/Prep.hs
• compiler/GHC/Driver/Config/Core/Opt/Simplify.hs
• compiler/GHC/HsToCore.hs
• compiler/GHC/HsToCore/Expr.hs
• compiler/GHC/HsToCore/Pmc/Solver/Types.hs
• compiler/GHC/Tc/Instance/Class.hs
• compiler/GHC/Tc/Types/Origin.hs
• libraries/ghc-internal/src/GHC/Internal/Exts.hs
• libraries/ghc-internal/src/GHC/Internal/Magic.hs
• testsuite/tests/corelint/LintEtaExpand.hs
• + testsuite/tests/dmdanal/should_compile/T23911.hs
• + testsuite/tests/dmdanal/should_compile/T23911.stderr
• testsuite/tests/dmdanal/should_compile/all.T
• testsuite/tests/interface-stability/base-exports.stdout
• testsuite/tests/interface-stability/base-exports.stdout-mingw32
• testsuite/tests/interface-stability/ghc-experimental-exports.stdout
• testsuite/tests/interface-stability/ghc-experimental-exports.stdout-mingw32
• testsuite/tests/interface-stability/ghc-prim-exports.stdout
• testsuite/tests/interface-stability/ghc-prim-exports.stdout-mingw32
• testsuite/tests/simplCore/should_compile/T18995.stderr
• + testsuite/tests/simplCore/should_compile/T27724a.hs
• + testsuite/tests/simplCore/should_compile/T27724a.stderr
• + testsuite/tests/simplCore/should_compile/T27803.hs
• + testsuite/tests/simplCore/should_compile/T27803.stderr
• testsuite/tests/simplCore/should_compile/all.T
• testsuite/tests/typecheck/should_fail/T17940.stderr
• utils/genprimopcode/Main.hs

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