diff options
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/loop.c | 13 |
2 files changed, 17 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b4c81e70acd..8b1ca6fb1ef 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2004-06-16 Dale Johannesen <dalej@apple.com> + + * loop.c (loop_givs_reduce): Avoid miscompilation of + loops entered at bottom. + 2004-06-16 J"orn Rennecke <joern.rennecke@superh.com> * cfglayout.c (fixup_reorder_chain): Handle case where the diff --git a/gcc/loop.c b/gcc/loop.c index fd0c0d64354..aafb18c02f9 100644 --- a/gcc/loop.c +++ b/gcc/loop.c @@ -4699,13 +4699,24 @@ loop_givs_reduce (struct loop *loop, struct iv_class *bl) this is an address giv, then try to put the increment immediately after its use, so that flow can create an auto-increment addressing mode. */ + /* Don't do this for loops entered at the bottom, to avoid + this invalid transformation: + jmp L; -> jmp L; + TOP: TOP: + use giv use giv + L: inc giv + inc biv L: + test biv test giv + cbr TOP cbr TOP + */ if (v->giv_type == DEST_ADDR && bl->biv_count == 1 && bl->biv->always_executed && ! bl->biv->maybe_multiple /* We don't handle reversed biv's because bl->biv->insn does not have a valid INSN_LUID. */ && ! bl->reversed && v->always_executed && ! v->maybe_multiple - && INSN_UID (v->insn) < max_uid_for_loop) + && INSN_UID (v->insn) < max_uid_for_loop + && !loop->top) { /* If other giv's have been combined with this one, then this will work only if all uses of the other giv's occur |