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ifcvt.c (total_bb_rtx_cost): Rename function to cheap_bb_rtx_cost_p.

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* 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
This commit is contained in:
Roger Sayle 2004-12-18 15:26:32 +00:00 committed by Roger Sayle
parent dbedefae43
commit 4fb735e4bf
2 changed files with 35 additions and 15 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2004-12-18 Roger Sayle <roger@eyesopen.com>
* 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 <roger@eyesopen.com>
PR middle-end/18548

43
gcc/ifcvt.c
View File

@ -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. */