From: Simon Marlow Date: Tue, 24 May 2011 12:18:55 +0000 (+0100) Subject: make the change to go_pap suggested in #4978. According to nofib, one X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=f43bedeef3ecdf4d037a2484a0f0a3672ab60299 make the change to go_pap suggested in #4978. According to nofib, one program is improved quite dramatically (fft2 30% less allocation), and everything else was unchanged. --- diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs index a0a229f..4146b62 100644 --- a/compiler/coreSyn/CoreUtils.lhs +++ b/compiler/coreSyn/CoreUtils.lhs @@ -589,12 +589,10 @@ exprIsCheap' good_app other_expr -- Applications and variables go _ _ = False -------------- - go_pap args = all exprIsTrivial args - -- For constructor applications and primops, check that all - -- the args are trivial. We don't want to treat as cheap, say, - -- (1:2:3:4:5:[]) - -- We'll put up with one constructor application, but not dozens - + go_pap args = all (exprIsCheap' good_app) args + -- Used to be "all exprIsTrivial args" due to concerns about + -- duplicating nested constructor applications, but see #4978. + -------------- go_primop op args = primOpIsCheap op && all (exprIsCheap' good_app) args -- In principle we should worry about primops