From b09d108b488516d1fc8225ab460799d5e8c6dab9 Mon Sep 17 00:00:00 2001 From: Josef Zlomek Date: Fri, 21 Dec 2001 02:50:10 +0100 Subject: [PATCH] cfgloop.c (flow_loops_find): Use the information of the depth first search order of the CFG correctly when... * cfgloop.c (flow_loops_find): Use the information of the depth first search order of the CFG correctly when finding natural loops. From-SVN: r48227 --- gcc/ChangeLog | 5 +++++ gcc/cfgloop.c | 28 ++++++++++++++-------------- 2 files changed, 19 insertions(+), 14 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5caed01b48d..0db4281e989 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2001-12-20 Josef Zlomek + + * cfgloop.c (flow_loops_find): Use the information of the depth + first search order of the CFG correctly when finding natural loops. + 2001-12-20 Richard Henderson * config/alpha/alpha.md (prologue_mcount): Update for explicit relocs. diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c index cabd2f22299..a94cbfe79b9 100644 --- a/gcc/cfgloop.c +++ b/gcc/cfgloop.c @@ -737,26 +737,26 @@ flow_loops_find (loops, flags) /* Find and record information about all the natural loops in the CFG. */ num_loops = 0; - for (b = 0; b < n_basic_blocks; b++) + for (b = n_basic_blocks - 1; b >= 0; b--) { - basic_block header; + basic_block latch; /* Search the nodes of the CFG in reverse completion order so that we can find outer loops first. */ - header = BASIC_BLOCK (rc_order[b]); + latch = BASIC_BLOCK (rc_order[b]); - /* Look for all the possible latch blocks for this header. */ - for (e = header->pred; e; e = e->pred_next) + /* Look for all the possible headers for this latch block. */ + for (e = latch->succ; e; e = e->succ_next) { - basic_block latch = e->src; - - /* Look for back edges where a predecessor is dominated - by this block. A natural loop has a single entry - node (header) that dominates all the nodes in the - loop. It also has single back edge to the header - from a latch node. Note that multiple natural loops - may share the same header. */ - if (latch != ENTRY_BLOCK_PTR + basic_block header = e->dest; + + /* Look for forward edges where this block is dominated by + a successor of this block. A natural loop has a single + entry node (header) that dominates all the nodes in the + loop. It also has single back edge to the header from a + latch node. Note that multiple natural loops may share + the same header. */ + if (header != EXIT_BLOCK_PTR && TEST_BIT (dom[latch->index], header->index)) { struct loop *loop; -- 2.30.2