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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2011-09-23 06:46:30 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2011-09-23 06:46:30 +0100 |
| commit | 24a2353a77111e9f236325521edd233f35954328 (patch) | |
| tree | 4d25308abe4fa1d80404c2daeaf10eb0781849c2 /compiler/simplCore/SimplCore.lhs | |
| parent | 730f6c6e81cd4cd2cf03c6a1e6dbdcb77b1f089e (diff) | |
| download | haskell-24a2353a77111e9f236325521edd233f35954328.tar.gz | |
Add a transformation limit to the simplifier (Trac #5448)
This addresses the rare cases where the simplifier diverges
(see the above ticket). We were already counting how many simplifier
steps were taking place, but with no limit. This patch adds a limit;
at which point we halt compilation, and print out useful stats. The
stats show what is begin inlined, and how often, which points you
directly to the problem. The limit is set based on the size of the
program.
Instead of halting compilation, we could instead just inhibit
inlining, which would let compilation of the module complete. This is
a bit harder to implement, and it's likely to mean that you unrolled
the function 1143 times and then ran out of ticks; you probably don't
want to complete parsing on this highly-unrolled program.
Flags: -dsimpl-tick-factor=N. Default is 100 (percent).
A bigger number increases the allowed maximum tick count.
Diffstat (limited to 'compiler/simplCore/SimplCore.lhs')
| -rw-r--r-- | compiler/simplCore/SimplCore.lhs | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/compiler/simplCore/SimplCore.lhs b/compiler/simplCore/SimplCore.lhs index 20425db8f6..3c89b0fa5d 100644 --- a/compiler/simplCore/SimplCore.lhs +++ b/compiler/simplCore/SimplCore.lhs @@ -18,7 +18,7 @@ import Rules ( RuleBase, emptyRuleBase, mkRuleBase, unionRuleBase, import PprCore ( pprCoreBindings, pprCoreExpr ) import OccurAnal ( occurAnalysePgm, occurAnalyseExpr ) import IdInfo -import CoreUtils ( coreBindsSize ) +import CoreUtils ( coreBindsSize, exprSize ) import Simplify ( simplTopBinds, simplExpr ) import SimplUtils ( simplEnvForGHCi, activeRule ) import SimplEnv @@ -478,7 +478,8 @@ simplifyExpr dflags expr ; us <- mkSplitUniqSupply 's' - ; let (expr', _counts) = initSmpl dflags emptyRuleBase emptyFamInstEnvs us $ + ; let sz = exprSize expr + (expr', _counts) = initSmpl dflags emptyRuleBase emptyFamInstEnvs us sz $ simplExprGently (simplEnvForGHCi dflags) expr ; Err.dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression" @@ -581,7 +582,8 @@ simplifyPgmIO pass@(CoreDoSimplify max_iterations mode) -- Try and force thunks off the binds; significantly reduces -- space usage, especially with -O. JRS, 000620. - | let sz = coreBindsSize binds in sz == sz + | let sz = coreBindsSize binds + , sz == sz -- Force it = do { -- Occurrence analysis let { -- During the 'InitialPhase' (i.e., before vectorisation), we need to make sure @@ -620,7 +622,7 @@ simplifyPgmIO pass@(CoreDoSimplify max_iterations mode) -- case t of {(_,counts1) -> if counts1=0 then ... } -- So the conditional didn't force counts1, because the -- selection got duplicated. Sigh! - case initSmpl dflags rule_base2 fam_envs us1 simpl_binds of { + case initSmpl dflags rule_base2 fam_envs us1 sz simpl_binds of { (env1, counts1) -> do { let { binds1 = getFloats env1 |