From: simonpj@microsoft.com <unknown>
Date: Wed, 5 Mar 2008 15:57:08 +0000 (+0000)
Subject: Refactor OccAnal; and improve dead-code elimination
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=6dc702e8e8b744196b5841729d16d03f83218834;hp=6dc702e8e8b744196b5841729d16d03f83218834;p=ghc-hetmet.git

Refactor OccAnal; and improve dead-code elimination

The occurrence analyer is now really rather subtle when dealing
with recursive groups; see Note [Loop breaking and RULES] especially.

This patch refactors this code a bit, notably
  * Introduces a new data type Details instead of a tuple

  * More clearly breaks up a recursive group into its SCCs
	before processing it in a separate function occAnalRec

  * As a result, does better dead-code elimination, becuause it's
   	done per SCC rather than for the whole Rec
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