This RFC patch implements conversion of COND_EXEC instructions to control flow
for pre-RA selective scheduler. Something like this is needed to employ
predication support before reload.
Each COND_EXEC is converted separately to a new basic block with the
unconditional variant of the instruction, and a conditional jump around it.
I'm not sure what would be an acceptable approach here. I'm also not sure
about the recommended way to emit JUMPs.
2011-10-26 Sergey Grechanik <mouseent...@ispras.ru>
* sel-sched.c (convert_cond_execs): New. Use it...
(sel_global_finish): ... here.
diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index f5c6f8b..b8f2663 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -45,6 +45,7 @@ along with GCC; see the file COPYING3. If not see
#include "rtlhooks-def.h"
#include "output.h"
#include "emit-rtl.h"
+#include "cfghooks.h"
#ifdef INSN_SCHEDULING
#include "sel-sched-ir.h"
@@ -7978,6 +7979,60 @@ sel_global_init (void)
init_hard_regs_data ();
}
+/* Convert cond_execs to jumps before reload. */
+static void
+convert_cond_execs (void)
+{
+ basic_block bb;
+ rtx insn;
+
+ if (reload_completed)
+ return;
+
+ FOR_EACH_BB (bb)
+ /* We don't need the safe variant because we break immediately after
+ removing the current instruction. */
+ FOR_BB_INSNS (bb, insn)
+ if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == COND_EXEC)
+ {
+ rtx jump;
+ rtx cond = COND_EXEC_TEST (PATTERN (insn));
+ rtx rcond = reversed_comparison (cond, GET_MODE (cond));
+ rtx unpredicated = copy_rtx (COND_EXEC_CODE (PATTERN (insn)));
+
+ /* Split bb into BB, NEW_BB, NEXT_BB (in that order). */
+ edge e1 = split_block (bb, insn);
+ basic_block next_bb = e1->dest;
+ edge e2 = split_block (bb, insn);
+ basic_block new_bb = e2->dest;
+
+ /* Emit conditional jump at the end of bb. */
+ rtx label = block_label (next_bb);
+
+ /* FIXME There should be a better way. */
+ rtx jump_pat
+ = gen_rtx_SET (GET_MODE (pc_rtx), pc_rtx,
+ gen_rtx_IF_THEN_ELSE (GET_MODE (pc_rtx),
+ rcond,
+ gen_rtx_LABEL_REF (VOIDmode,
+ label),
+ pc_rtx));
+
+ make_edge (bb, next_bb, 0);
+ jump = emit_jump_insn_after (jump_pat, BB_END (bb));
+ JUMP_LABEL (jump) = label;
+ LABEL_NUSES (label)++;
+
+ emit_insn_after_noloc (unpredicated, BB_HEAD (new_bb), new_bb);
+
+ delete_insn (insn);
+ break;
+ }
+#ifdef ENABLE_CHECKING
+ verify_flow_info ();
+#endif
+}
+
/* Free the global data of the scheduler. */
static void
sel_global_finish (void)
@@ -7998,6 +8053,8 @@ sel_global_finish (void)
free_sched_pools ();
free_dominance_info (CDI_DOMINATORS);
+
+ convert_cond_execs ();
}
/* Return true when we need to skip selective scheduling. Used for debugging.
*/
