Make SetLevels do substitution properly (fixes Trac #8714)
Nowadays SetLevels floats case expressions as well as let-bindings, and case expressions bind type variables. We need to clone all such floated binders, to avoid accidental name capture. But I'd forgotten to substitute for the cloned type variables, causing #8714. (In the olden days only Ids were cloned, from let-bindings.) This patch fixes the bug and does quite a bit of clean-up refactoring as well, by putting the context level in the LvlEnv. There is no effect on performance, except that nofib 'rewrite' improves allocations by 3%. On investigation I think it was a fluke to do with loop-cutting in big letrec nests. But at least it's a fluke in the right direction. Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- Min -0.4% -3.0% -19.4% -19.4% -26.7% Max -0.0% +0.0% +17.9% +17.9% 0.0% Geometric Mean -0.1% -0.0% -0.7% -0.7% -0.4%
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- compiler/coreSyn/CoreSubst.lhs 1 addition, 1 deletioncompiler/coreSyn/CoreSubst.lhs
- compiler/coreSyn/CoreSyn.lhs 20 additions, 1 deletioncompiler/coreSyn/CoreSyn.lhs
- compiler/simplCore/SetLevels.lhs 292 additions, 332 deletionscompiler/simplCore/SetLevels.lhs
- testsuite/tests/simplCore/should_compile/T8714.hs 9 additions, 0 deletionstestsuite/tests/simplCore/should_compile/T8714.hs
- testsuite/tests/simplCore/should_compile/all.T 1 addition, 0 deletionstestsuite/tests/simplCore/should_compile/all.T
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