Hi, The patch splits the live_edge for move_insn_for_shrink_wrap to sink the copy out of the entry block.
Bootstrap and no make check regression on X86-64 and ARM. OK for trunk? Thanks! -Zhenqiang ChangeLog: 2014-05-08 Zhenqiang Chen <zhenqiang.c...@linaro.org> * function.c (next_block_for_reg): Allow live_edge->dest has two predecessors. (move_insn_for_shrink_wrap): Split live_edge. (prepre_shrink_wrap): One more parameter for move_insn_for_shrink_wrap. diff --git a/gcc/function.c b/gcc/function.c index 764ac82..0be58e2 100644 --- a/gcc/function.c +++ b/gcc/function.c @@ -5381,7 +5381,7 @@ requires_stack_frame_p (rtx insn, HARD_REG_SET prologue_used, and if BB is its only predecessor. Return that block if so, otherwise return null. */ -static basic_block +static edge next_block_for_reg (basic_block bb, int regno, int end_regno) { edge e, live_edge; @@ -5415,10 +5415,12 @@ next_block_for_reg (basic_block bb, int regno, int end_regno) if (live_edge->flags & EDGE_ABNORMAL) return NULL; - if (EDGE_COUNT (live_edge->dest->preds) > 1) + /* When live_edge->dest->preds == 2, we can create a new block on + the edge to make it meet the requirement. */ + if (EDGE_COUNT (live_edge->dest->preds) > 2) return NULL; - return live_edge->dest; + return live_edge; } /* Check whether INSN is the last insn in BB or @@ -5545,20 +5547,25 @@ try_copy_prop (basic_block bb, rtx insn, rtx src, rtx dest, return ret; } - /* Try to move INSN from BB to a successor. Return true on success. - USES and DEFS are the set of registers that are used and defined - after INSN in BB. */ +/* Try to move INSN from BB to a successor. Return true on success. + LAST_USES is the set of registers that are used by the COMPARE or JUMP + instructions in the block. USES is the set of registers that are used + by others after INSN except COMARE and JUMP. DEFS are the set of registers + that are used and defined others after INSN. SPLIT_P indicates whether + a live edge from BB is splitted or not. */ static bool move_insn_for_shrink_wrap (basic_block bb, rtx insn, const HARD_REG_SET uses, const HARD_REG_SET defs, - HARD_REG_SET *last_uses) + HARD_REG_SET *last_uses, + bool *split_p) { rtx set, src, dest; bitmap live_out, live_in, bb_uses, bb_defs; unsigned int i, dregno, end_dregno, sregno, end_sregno; basic_block next_block; + edge live_edge; /* Look for a simple register copy. */ set = single_set (insn); @@ -5582,17 +5589,31 @@ move_insn_for_shrink_wrap (basic_block bb, rtx insn, || overlaps_hard_reg_set_p (defs, GET_MODE (dest), dregno)) return false; - /* See whether there is a successor block to which we could move INSN. */ - next_block = next_block_for_reg (bb, dregno, end_dregno); - if (!next_block) + live_edge = next_block_for_reg (bb, dregno, end_dregno); + if (!live_edge) return false; + next_block = live_edge->dest; + /* If the destination register is referred in later insn, try to forward it. */ if (overlaps_hard_reg_set_p (*last_uses, GET_MODE (dest), dregno) && !try_copy_prop (bb, insn, src, dest, last_uses)) return false; + /* Create a new basic block on the edge. */ + if (EDGE_COUNT (next_block->preds) == 2) + { + next_block = split_edge (live_edge); + + bitmap_copy (df_get_live_in (next_block), df_get_live_out (bb)); + df_set_bb_dirty (next_block); + + /* We should not split more than once for a function. */ + gcc_assert (!(*split_p)); + *split_p = true; + } + /* At this point we are committed to moving INSN, but let's try to move it as far as we can. */ do @@ -5610,7 +5631,10 @@ move_insn_for_shrink_wrap (basic_block bb, rtx insn, { for (i = dregno; i < end_dregno; i++) { - if (REGNO_REG_SET_P (bb_uses, i) || REGNO_REG_SET_P (bb_defs, i) + + if (*split_p + || REGNO_REG_SET_P (bb_uses, i) + || REGNO_REG_SET_P (bb_defs, i) || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i)) next_block = NULL; CLEAR_REGNO_REG_SET (live_out, i); @@ -5621,7 +5645,8 @@ move_insn_for_shrink_wrap (basic_block bb, rtx insn, Either way, SRC is now live on entry. */ for (i = sregno; i < end_sregno; i++) { - if (REGNO_REG_SET_P (bb_defs, i) + if (*split_p + || REGNO_REG_SET_P (bb_defs, i) || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i)) next_block = NULL; SET_REGNO_REG_SET (live_out, i); @@ -5650,21 +5675,31 @@ move_insn_for_shrink_wrap (basic_block bb, rtx insn, /* If we don't need to add the move to BB, look for a single successor block. */ if (next_block) - next_block = next_block_for_reg (next_block, dregno, end_dregno); + { + live_edge = next_block_for_reg (next_block, dregno, end_dregno); + if (!live_edge || EDGE_COUNT (live_edge->dest->preds) > 1) + break; + next_block = live_edge->dest; + } } while (next_block); - /* BB now defines DEST. It only uses the parts of DEST that overlap SRC - (next loop). */ - for (i = dregno; i < end_dregno; i++) + /* For the new created basic block, there is no dataflow info at all. + So skip the following dataflow update and check. */ + if (!(*split_p)) { - CLEAR_REGNO_REG_SET (bb_uses, i); - SET_REGNO_REG_SET (bb_defs, i); - } + /* BB now defines DEST. It only uses the parts of DEST that overlap SRC + (next loop). */ + for (i = dregno; i < end_dregno; i++) + { + CLEAR_REGNO_REG_SET (bb_uses, i); + SET_REGNO_REG_SET (bb_defs, i); + } - /* BB now uses SRC. */ - for (i = sregno; i < end_sregno; i++) - SET_REGNO_REG_SET (bb_uses, i); + /* BB now uses SRC. */ + for (i = sregno; i < end_sregno; i++) + SET_REGNO_REG_SET (bb_uses, i); + } emit_insn_after (PATTERN (insn), bb_note (bb)); delete_insn (insn); @@ -5684,6 +5719,7 @@ prepare_shrink_wrap (basic_block entry_block) rtx insn, curr, x; HARD_REG_SET uses, defs, last_uses; df_ref *ref; + bool split_p = false; if (!JUMP_P (BB_END (entry_block))) return; @@ -5693,7 +5729,7 @@ prepare_shrink_wrap (basic_block entry_block) FOR_BB_INSNS_REVERSE_SAFE (entry_block, insn, curr) if (NONDEBUG_INSN_P (insn) && !move_insn_for_shrink_wrap (entry_block, insn, uses, defs, - &last_uses)) + &last_uses, &split_p)) { /* Add all defined registers to DEFs. */ for (ref = DF_INSN_DEFS (insn); *ref; ref++)