Combine can turn a conditional trap into an unconditional trap. If it
does that it should make the code after it unreachable (an unconditional
trap should be the last insn in its bb, and that bb has no successors).
This patch seems to work. It is hard to be sure, this is very hard to
trigger. Quite a few other passes look like they need something similar
as well, but I don't see anything else handling it yet either.
How does this look? Any better ideas?
Segher
---
gcc/combine.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/gcc/combine.c b/gcc/combine.c
index 18777f8..90397f58 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -82,6 +82,7 @@ along with GCC; see the file COPYING3. If not see
#include "target.h"
#include "rtl.h"
#include "tree.h"
+#include "cfghooks.h"
#include "predict.h"
#include "df.h"
#include "memmodel.h"
@@ -4648,6 +4649,25 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1,
rtx_insn *i0,
update_cfg_for_uncondjump (undobuf.other_insn);
}
+ if (GET_CODE (PATTERN (i3)) == TRAP_IF
+ && XEXP (PATTERN (i3), 0) == const1_rtx)
+ {
+ basic_block bb = BLOCK_FOR_INSN (i3);
+ gcc_assert (bb);
+ remove_edge (split_block (bb, i3));
+ *new_direct_jump_p = 1;
+ }
+
+ if (undobuf.other_insn
+ && GET_CODE (PATTERN (undobuf.other_insn)) == TRAP_IF
+ && XEXP (PATTERN (undobuf.other_insn), 0) == const1_rtx)
+ {
+ basic_block bb = BLOCK_FOR_INSN (undobuf.other_insn);
+ gcc_assert (bb);
+ remove_edge (split_block (bb, undobuf.other_insn));
+ *new_direct_jump_p = 1;
+ }
+
/* A noop might also need cleaning up of CFG, if it comes from the
simplification of a jump. */
if (JUMP_P (i3)
--
1.9.3
