diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/cprop.c | 34 |
2 files changed, 16 insertions, 25 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 53bbd71..f0563db 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,12 @@ 2012-12-21 Richard Biener <rguenther@suse.de> + PR rtl-optimization/52996 + * cprop.c (bypass_block): When loops are to be preserved + do not bypass loop headers. Revert earlier kludge to remove + loops when doing that. + +2012-12-21 Richard Biener <rguenther@suse.de> + PR bootstrap/54659 * system.h: Include gmp.h. * tree-ssa-loop-niter.c: Do not include gmp.h here. diff --git a/gcc/cprop.c b/gcc/cprop.c index ec896a4..463f81f 100644 --- a/gcc/cprop.c +++ b/gcc/cprop.c @@ -1496,7 +1496,7 @@ bypass_block (basic_block bb, rtx setcc, rtx jump) rtx insn, note; edge e, edest; int change; - int may_be_loop_header; + int may_be_loop_header = false; unsigned removed_p; unsigned i; edge_iterator ei; @@ -1510,27 +1510,22 @@ bypass_block (basic_block bb, rtx setcc, rtx jump) if (note) find_used_regs (&XEXP (note, 0), NULL); - /* Determine whether there are more latch edges. Threading through - a loop header with more than one latch is delicate, see e.g. - tree-ssa-threadupdate.c:thread_through_loop_header. */ if (current_loops) { - may_be_loop_header = bb == bb->loop_father->header; - if (may_be_loop_header - && bb->loop_father->latch == NULL) + /* If we are to preserve loop structure then do not bypass + a loop header. This will either rotate the loop, create + multiple entry loops or even irreducible regions. */ + if (bb == bb->loop_father->header) return 0; } else { - unsigned n_back_edges = 0; FOR_EACH_EDGE (e, ei, bb->preds) if (e->flags & EDGE_DFS_BACK) - n_back_edges++; - - may_be_loop_header = n_back_edges > 0; - - if (n_back_edges > 1) - return 0; + { + may_be_loop_header = true; + break; + } } change = 0; @@ -1619,17 +1614,6 @@ bypass_block (basic_block bb, rtx setcc, rtx jump) && dest != old_dest && dest != EXIT_BLOCK_PTR) { - if (current_loops != NULL - && e->src->loop_father->latch == e->src) - { - /* ??? Now we are creating (or may create) a loop - with multiple entries. Simply mark it for - removal. Alternatively we could not do this - threading. */ - e->src->loop_father->header = NULL; - e->src->loop_father->latch = NULL; - } - redirect_edge_and_branch_force (e, dest); /* Copy the register setter to the redirected edge. |