From 4fb735e4bff30d180a4cfe05582d9f5c1fa8db7a Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Sat, 18 Dec 2004 15:26:32 +0000 Subject: [PATCH] ifcvt.c (total_bb_rtx_cost): Rename function to cheap_bb_rtx_cost_p. * ifcvt.c (total_bb_rtx_cost): Rename function to cheap_bb_rtx_cost_p. Take a max_cost argument to avoid scanning large blocks, by returning a Boolean instead of a total. Include the cost of a "fstp %st(0)" instruction required to pop dead values off of a register stack. From-SVN: r92352 --- gcc/ChangeLog | 7 +++++++ gcc/ifcvt.c | 43 ++++++++++++++++++++++++++++--------------- 2 files changed, 35 insertions(+), 15 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 024e48bbcef..55c29f99660 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2004-12-18 Roger Sayle + + * ifcvt.c (total_bb_rtx_cost): Rename function to cheap_bb_rtx_cost_p. + Take a max_cost argument to avoid scanning large blocks, by returning + a Boolean instead of a total. Include the cost of a "fstp %st(0)" + instruction required to pop dead values off of a register stack. + 2004-12-18 Roger Sayle PR middle-end/18548 diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 7f67a9a61a5..98fbd667a01 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -86,7 +86,7 @@ static bool life_data_ok; /* Forward references. */ static int count_bb_insns (basic_block); -static int total_bb_rtx_cost (basic_block); +static bool cheap_bb_rtx_cost_p (basic_block, int); static rtx first_active_insn (basic_block); static rtx last_active_insn (basic_block, int); static basic_block block_fallthru (basic_block); @@ -162,12 +162,12 @@ count_bb_insns (basic_block bb) return count; } -/* Count the total insn_rtx_cost of non-jump active insns in BB. - This function returns -1, if the cost of any instruction could - not be estimated. */ +/* Determine whether the total insn_rtx_cost on non-jump insns in + basic block BB is less than MAX_COST. This function returns + false if the cost of any instruction could not be estimated. */ -static int -total_bb_rtx_cost (basic_block bb) +static bool +cheap_bb_rtx_cost_p (basic_block bb, int max_cost) { int count = 0; rtx insn = BB_HEAD (bb); @@ -178,18 +178,34 @@ total_bb_rtx_cost (basic_block bb) { int cost = insn_rtx_cost (PATTERN (insn)); if (cost == 0) - return -1; + return false; + + /* If this instruction is the load or set of a "stack" register, + such as a floating point register on x87, then the cost of + speculatively executing this instruction needs to include + the additional cost of popping this register off of the + register stack. */ +#ifdef STACK_REGS + { + rtx set = single_set (insn); + if (set && STACK_REG_P (SET_DEST (set))) + cost += COSTS_N_INSNS (1); + } +#endif + count += cost; + if (count >= max_cost) + return false; } else if (CALL_P (insn)) - return -1; + return false; if (insn == BB_END (bb)) break; insn = NEXT_INSN (insn); } - return count; + return true; } /* Return the first non-jump active insn in the basic block. */ @@ -2853,7 +2869,7 @@ find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge) { basic_block then_bb = then_edge->dest; basic_block else_bb = else_edge->dest, new_bb; - int then_bb_index, bb_cost; + int then_bb_index; /* If we are partitioning hot/cold basic blocks, we don't want to mess up unconditional or indirect jumps that cross between hot @@ -2896,8 +2912,7 @@ find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge) test_bb->index, then_bb->index); /* THEN is small. */ - bb_cost = total_bb_rtx_cost (then_bb); - if (bb_cost < 0 || bb_cost >= COSTS_N_INSNS (BRANCH_COST)) + if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST))) return FALSE; /* Registers set are dead, or are predicable. */ @@ -2944,7 +2959,6 @@ find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge) basic_block then_bb = then_edge->dest; basic_block else_bb = else_edge->dest; edge else_succ; - int bb_cost; rtx note; /* If we are partitioning hot/cold basic blocks, we don't want to @@ -3001,8 +3015,7 @@ find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge) test_bb->index, else_bb->index); /* ELSE is small. */ - bb_cost = total_bb_rtx_cost (else_bb); - if (bb_cost < 0 || bb_cost >= COSTS_N_INSNS (BRANCH_COST)) + if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST))) return FALSE; /* Registers set are dead, or are predicable. */