This is the first part in fixing PR target/120372.
The current code for canonicalize_comparison, uses gen_move_insn and rtx_cost
to find
out the cost of generating a constant. This is ok in most cases except sometimes
the comparison instruction can handle different constants than a simple set
intruction can do. This changes to use rtx_cost directly with the outer being
COMPARE
just like how prepare_cmp_insn handles that.
Note this is also a small speedup and small memory improvement because we are
not creating
a move for the constant any more. Since we are not creating a psedu-register
any more, this
also removes the check on that.
Also adds a dump so we can see why one choice was chosen over the other.
Build and tested for aarch64-linux-gnu.
gcc/ChangeLog:
* expmed.cc (canonicalize_comparison): Use rtx_cost directly
instead of gen_move_insn. Print out the choice if dump is enabled.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
gcc/expmed.cc | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/gcc/expmed.cc b/gcc/expmed.cc
index 72dbafe5d9f..d5da199d033 100644
--- a/gcc/expmed.cc
+++ b/gcc/expmed.cc
@@ -6408,18 +6408,25 @@ canonicalize_comparison (machine_mode mode, enum
rtx_code *code, rtx *imm)
if (overflow)
return;
- /* The following creates a pseudo; if we cannot do that, bail out. */
- if (!can_create_pseudo_p ())
- return;
-
- rtx reg = gen_rtx_REG (mode, LAST_VIRTUAL_REGISTER + 1);
rtx new_imm = immed_wide_int_const (imm_modif, mode);
- rtx_insn *old_rtx = gen_move_insn (reg, *imm);
- rtx_insn *new_rtx = gen_move_insn (reg, new_imm);
+ int old_cost = rtx_cost (*imm, mode, COMPARE, 0, true);
+ int new_cost = rtx_cost (new_imm, mode, COMPARE, 0, true);
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, ";; cmp: %s, old cst: ",
+ GET_RTX_NAME (*code));
+ print_rtl (dump_file, *imm);
+ fprintf (dump_file, " new cst: ");
+ print_rtl (dump_file, new_imm);
+ fprintf (dump_file, "\n");
+ fprintf (dump_file, ";; old cst cost: %d, new cst cost: %d\n",
+ old_cost, new_cost);
+ }
/* Update the immediate and the code. */
- if (insn_cost (old_rtx, true) > insn_cost (new_rtx, true))
+ if (old_cost > new_cost)
{
*code = equivalent_cmp_code (*code);
*imm = new_imm;
--
2.43.0
