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| author | Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz> | 2003-03-08 10:47:28 +0100 |
|---|---|---|
| committer | Zdenek Dvorak <rakdver@gcc.gnu.org> | 2003-03-08 09:47:28 +0000 |
| commit | 72b8d451f1b0c3bef4b3afc688ada5d5175d97d0 (patch) | |
| tree | 2049f3fc3ca464bc5ba32b5c28fce7018ba25366 /gcc/gcse.c | |
| parent | 612dc71803c6a8419ad07b13462dd15732d650b4 (diff) | |
| download | gcc-72b8d451f1b0c3bef4b3afc688ada5d5175d97d0.tar.gz | |
gcse.c (bypass_block, [...]): Do not create irreducible loops.
* gcse.c (bypass_block, bypass_conditional_jumps): Do not create
irreducible loops.
* loop-unroll.c (unroll_loop_runtime_iterations): Update irreducible
loops info correctly.
From-SVN: r63980
Diffstat (limited to 'gcc/gcse.c')
| -rw-r--r-- | gcc/gcse.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/gcc/gcse.c b/gcc/gcse.c index f5bb66d0053..f0e588ecd49 100644 --- a/gcc/gcse.c +++ b/gcc/gcse.c @@ -4759,6 +4759,7 @@ bypass_block (bb, setcc, jump) rtx insn, note; edge e, enext; int i, change; + int may_be_loop_header; insn = (setcc != NULL) ? setcc : jump; @@ -4769,6 +4770,14 @@ bypass_block (bb, setcc, jump) if (note) find_used_regs (&XEXP (note, 0), NULL); + may_be_loop_header = false; + for (e = bb->pred; e; e = e->pred_next) + if (e->flags & EDGE_DFS_BACK) + { + may_be_loop_header = true; + break; + } + change = 0; for (e = bb->pred; e; e = enext) { @@ -4780,6 +4789,13 @@ bypass_block (bb, setcc, jump) if (e->src->index >= bypass_last_basic_block) continue; + /* The irreducible loops created by redirecting of edges entering the + loop from outside would decrease effectivity of some of the following + optimalizations, so prevent this. */ + if (may_be_loop_header + && !(e->flags & EDGE_DFS_BACK)) + continue; + for (i = 0; i < reg_use_count; i++) { struct reg_use *reg_used = ®_use_table[i]; @@ -4866,6 +4882,7 @@ bypass_conditional_jumps () return 0; bypass_last_basic_block = last_basic_block; + mark_dfs_back_edges (); changed = 0; FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, |