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[taken from gcc-2.96]

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Mon Jul 31 22:19:24 2000  Jeffrey A Law  (law@cygnus.com)
   * loop.c (check_dbra_loop): Make change from July 17, 2000 work
   on targets which need more than one insn for a compare/cbranch
   operation.
	* gcc-c-torture/execute/20000731-2.c: New test.


git-svn-id: file:///srv/svn/repos/haiku/trunk/buildtools@9610 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Oliver Tappe 2004-10-28 18:29:22 +00:00
parent 3428817f1c
commit 1e55f532cb
1 changed files with 18 additions and 3 deletions
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21
gcc/gcc/loop.c
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@ -330,7 +330,7 @@ static int basic_induction_var PROTO((rtx, enum machine_mode, rtx, rtx, rtx *, r
static rtx simplify_giv_expr PROTO((rtx, int *));
static int general_induction_var PROTO((rtx, rtx *, rtx *, rtx *, int, int *));
static int consec_sets_giv PROTO((int, rtx, rtx, rtx, rtx *, rtx *, rtx *));
static int check_dbra_loop PROTO((rtx, int, rtx, struct loop_info *));
static int check_dbra_loop PROTO((rtx, int, rtx, struct loop_info *, rtx));
static rtx express_from_1 PROTO((rtx, rtx, rtx));
static rtx combine_givs_p PROTO((struct induction *, struct induction *));
static void combine_givs PROTO((struct iv_class *));
@ -4602,7 +4602,7 @@ strength_reduce (scan_start, end, loop_top, insn_count,
/* Try to prove that the loop counter variable (if any) is always
nonnegative; if so, record that fact with a REG_NONNEG note
so that "decrement and branch until zero" insn can be used. */
check_dbra_loop (loop_end, insn_count, loop_start, loop_info);
check_dbra_loop (loop_end, insn_count, loop_start, loop_info, loop_cont);
/* Create reg_map to hold substitutions for replaceable giv regs.
Some givs might have been made from biv increments, so look at
@ -7699,11 +7699,12 @@ product_cheap_p (a, b)
final_[bg]iv_value. */
static int
check_dbra_loop (loop_end, insn_count, loop_start, loop_info)
check_dbra_loop (loop_end, insn_count, loop_start, loop_info, loop_cont)
rtx loop_end;
int insn_count;
rtx loop_start;
struct loop_info *loop_info;
rtx loop_cont;
{
struct iv_class *bl;
rtx reg;
@ -7736,6 +7737,20 @@ check_dbra_loop (loop_end, insn_count, loop_start, loop_info)
else
return 0;
{
/* If more than one condition is present to control the loop, then
do not proceed, as this function does not know how to rewrite
loop tests with more than one condition.
Look backwards from the first insn in the last comparison
sequence and see if we've got another comparison sequence. */
rtx jump1;
if ((jump1 = prev_nonnote_insn (first_compare)) != loop_cont)
if (GET_CODE (jump1) == JUMP_INSN)
return 0;
}
/* Check all of the bivs to see if the compare uses one of them.
Skip biv's set more than once because we can't guarantee that
it will be zero on the last iteration. Also skip if the biv is