From 55f7891bb79c49bca34c2866ca94fb754be30a88 Mon Sep 17 00:00:00 2001 From: Jeffrey A Law Date: Sun, 10 Oct 1999 05:30:28 +0000 Subject: [PATCH] gcse.c (gcse_main): Avoid global optimizations if we have a large number of basic blocks and the... * gcse.c (gcse_main): Avoid global optimizations if we have a large number of basic blocks and the ratio of edges to blocks is high. (delete_null_pointer_checks): Likewise. From-SVN: r29882 --- gcc/ChangeLog | 7 +++++++ gcc/gcse.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index da2340a6fea..340125313c9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +Sat Oct 9 23:26:55 1999 Jeffrey A Law (law@cygnus.com) + + * gcse.c (gcse_main): Avoid global optimizations if we have a + large number of basic blocks and the ratio of edges to blocks + is high. + (delete_null_pointer_checks): Likewise. + Sat Oct 9 23:16:01 1999 Ken Raeburn * c-common.c (check_format_info): Warn if format string isn't a diff --git a/gcc/gcse.c b/gcc/gcse.c index def34898cd7..cc9d2666dfb 100644 --- a/gcc/gcse.c +++ b/gcc/gcse.c @@ -672,6 +672,21 @@ gcse_main (f, file) return 0; } + /* Trying to perform global optimizations on flow graphs which have + a high connectivity will take a long time and is unlikely to be + particularly useful. + + In normal circumstances a cfg should have about twice has many edges + as blocks. But we do not want to punish small functions which have + a couple switch statements. So we require a relatively large number + of basic blocks and the ratio of edges to blocks to be high. */ + if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) + { + /* Free storage allocated by find_basic_blocks. */ + free_basic_block_vars (0); + return 0; + } + /* See what modes support reg/reg copy operations. */ if (! can_copy_init_p) { @@ -4908,6 +4923,21 @@ delete_null_pointer_checks (f) return; } + /* Trying to perform global optimizations on flow graphs which have + a high connectivity will take a long time and is unlikely to be + particularly useful. + + In normal circumstances a cfg should have about twice has many edges + as blocks. But we do not want to punish small functions which have + a couple switch statements. So we require a relatively large number + of basic blocks and the ratio of edges to blocks to be high. */ + if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20) + { + /* Free storage allocated by find_basic_blocks. */ + free_basic_block_vars (0); + return 0; + } + /* We need predecessor/successor lists as well as pred/succ counts for each basic block. */ s_preds = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr)); -- 2.30.2