This patch introduces more optimized implementations for the 6 cstoresi4
insn comparison methods (eq/ne/lt/le/gt/ge, however, required TARGET_NSA
for eq).
gcc/ChangeLog:
* config/xtensa/xtensa.cc (xtensa_expand_scc):
Add dedicated optimization code for cstoresi4 (eq/ne/gt/ge/lt/le).
* config/xtensa/xtensa.md (xtensa_ge_zero):
Rename from '*signed_ge_zero', because it had to be called from
'xtensa_expand_scc()'.
---
gcc/config/xtensa/xtensa.cc | 106 ++++++++++++++++++++++++++++++++----
gcc/config/xtensa/xtensa.md | 14 ++---
2 files changed, 102 insertions(+), 18 deletions(-)
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index 3b5d25b660a..64efd3d7287 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -991,24 +991,108 @@ xtensa_expand_conditional_move (rtx *operands, int isflt)
int
xtensa_expand_scc (rtx operands[4], machine_mode cmp_mode)
{
- rtx dest = operands[0];
- rtx cmp;
- rtx one_tmp, zero_tmp;
+ rtx dest = operands[0], op0 = operands[2], op1 = operands[3];
+ enum rtx_code code = GET_CODE (operands[1]);
+ rtx cmp, tmp0, tmp1;
rtx (*gen_fn) (rtx, rtx, rtx, rtx, rtx);
- if (!(cmp = gen_conditional_move (GET_CODE (operands[1]), cmp_mode,
- operands[2], operands[3])))
- return 0;
+ /* Dedicated optimizations for cstoresi4.
+ a. In a magnitude comparison operator, swapping both sides and
+ inverting magnitude does not change the result,
+ eg. '(x >= y) != (y <= x)' is a constant of zero
+ (GE is changed to LE, not LT).
+ b. Due to room for further optimization, we use subtraction rather
+ than XOR (the default for RTL expansion of EQ/NE) as the binary
+ operation which is zero if both sides are the same and non-zero
+ otherwise. */
+ if (cmp_mode == SImode)
+ switch (code)
+ {
+ /* EQ(op0, op1) := clz(op0 - op1) / 32 [requires TARGET_NSA] */
+ case EQ:
+ if (!TARGET_NSA)
+ break;
+ /* EQ to EQZ conversion by subtracting op1 from op0. */
+ emit_move_insn (dest,
+ expand_binop (SImode, sub_optab, op0, op1,
+ 0, 0, OPTAB_LIB_WIDEN));
+ /* NSAU instruction will return 32 iff the source is zero,
+ zero through 31 otherwise (See Xtensa ISA Reference Manual,
+ p. 462) */
+ emit_insn (gen_clzsi2 (dest, dest));
+ emit_insn (gen_lshrsi3 (dest, dest, GEN_INT (5)));
+ return 1;
+
+ /* NE(op0, op1) := (op0 - op1) == 0 ? 0 : 1 */
+ case NE:
+ /* NE to NEZ conversion by subtracting op1 from op0. */
+ emit_move_insn (tmp0 = gen_reg_rtx (SImode),
+ expand_binop (SImode, sub_optab, op0, op1,
+ 0, 0, OPTAB_LIB_WIDEN));
+ emit_move_insn (dest, const_true_rtx);
+ emit_move_insn (dest,
+ gen_rtx_fmt_eee (IF_THEN_ELSE, SImode,
+ gen_rtx_fmt_ee (EQ, VOIDmode,
+ tmp0, const0_rtx),
+ tmp0, dest));
+ return 1;
+
+ case LE:
+ if (REG_P (op1))
+ {
+ /* LE to GE conversion by swapping both sides. */
+ tmp0 = op0, op0 = op1, op1 = tmp0;
+ goto case_GE_reg;
+ }
+ /* LE to LT conversion by adding one to op1. */
+ op1 = GEN_INT (INTVAL (op1) + 1);
+ /* fallthru */
+
+ /* LT(op0, op1) := (unsigned)(op0 - op1) >> 31 */
+ case LT:
+case_LT:
+ /* LT to LTZ conversion by subtracting op1 from op0. */
+ emit_move_insn (dest,
+ expand_binop (SImode, sub_optab, op0, op1,
+ 0, 0, OPTAB_LIB_WIDEN));
+ emit_insn (gen_lshrsi3 (dest, dest, GEN_INT (31)));
+ return 1;
+
+ case GE:
+ if (REG_P (op1))
+ {
+case_GE_reg:
+ /* GE to GEZ conversion by subtracting op1 from op0. */
+ emit_move_insn (dest,
+ expand_binop (SImode, sub_optab, op0, op1,
+ 0, 0, OPTAB_LIB_WIDEN));
+ /* Emitting the dedicated insn pattern. */
+ emit_insn (gen_xtensa_ge_zero (dest, dest));
+ return 1;
+ }
+ /* GE to GT conversion by subtracting one from op1. */
+ op1 = GEN_INT (INTVAL (op1) - 1);
+ /* fallthru */
- one_tmp = gen_reg_rtx (SImode);
- zero_tmp = gen_reg_rtx (SImode);
- emit_insn (gen_movsi (one_tmp, const_true_rtx));
- emit_insn (gen_movsi (zero_tmp, const0_rtx));
+ case GT:
+ /* GT to LT conversion by swapping both sides. */
+ tmp0 = op0, op0 = op1, op1 = tmp0;
+ goto case_LT;
+ default:
+ break;
+ }
+
+ if (! (cmp = gen_conditional_move (code, cmp_mode, op0, op1)))
+ return 0;
+
+ tmp0 = force_reg (SImode, const0_rtx);
+ tmp1 = force_reg (SImode, const_true_rtx);
gen_fn = (cmp_mode == SImode
? gen_movsicc_internal0
: gen_movsicc_internal1);
- emit_insn (gen_fn (dest, XEXP (cmp, 0), one_tmp, zero_tmp, cmp));
+ emit_insn (gen_fn (dest, XEXP (cmp, 0), tmp1, tmp0, cmp));
+
return 1;
}
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 7870fb0bfce..ebc305bd387 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -196,8 +196,8 @@
(match_operand:DI 2 "register_operand")))]
""
{
- rtx_code_label *label = gen_label_rtx ();
rtx lo_dest, hi_dest, lo_op0, hi_op0, lo_op1, hi_op1;
+ rtx_code_label *label;
lo_dest = gen_lowpart (SImode, operands[0]);
hi_dest = gen_highpart (SImode, operands[0]);
lo_op0 = gen_lowpart (SImode, operands[1]);
@@ -209,8 +209,8 @@
emit_clobber (operands[0]);
emit_insn (gen_addsi3 (lo_dest, lo_op0, lo_op1));
emit_insn (gen_addsi3 (hi_dest, hi_op0, hi_op1));
- emit_cmp_and_jump_insns (lo_dest, lo_op1, GEU,
- const0_rtx, SImode, true, label);
+ emit_cmp_and_jump_insns (lo_dest, lo_op1, GEU, const0_rtx,
+ SImode, true, label = gen_label_rtx ());
emit_insn (gen_addsi3 (hi_dest, hi_dest, const1_rtx));
emit_label (label);
DONE;
@@ -269,8 +269,8 @@
(match_operand:DI 2 "register_operand")))]
""
{
- rtx_code_label *label = gen_label_rtx ();
rtx lo_dest, hi_dest, lo_op0, hi_op0, lo_op1, hi_op1;
+ rtx_code_label *label;
lo_dest = gen_lowpart (SImode, operands[0]);
hi_dest = gen_highpart (SImode, operands[0]);
lo_op0 = gen_lowpart (SImode, operands[1]);
@@ -282,8 +282,8 @@
emit_clobber (operands[0]);
emit_insn (gen_subsi3 (lo_dest, lo_op0, lo_op1));
emit_insn (gen_subsi3 (hi_dest, hi_op0, hi_op1));
- emit_cmp_and_jump_insns (lo_op0, lo_op1, GEU,
- const0_rtx, SImode, true, label);
+ emit_cmp_and_jump_insns (lo_op0, lo_op1, GEU, const0_rtx,
+ SImode, true, label = gen_label_rtx ());
emit_insn (gen_addsi3 (hi_dest, hi_dest, constm1_rtx));
emit_label (label);
DONE;
@@ -3136,7 +3136,7 @@
(const_int 5)
(const_int 6)))])
-(define_insn_and_split "*signed_ge_zero"
+(define_insn_and_split "xtensa_ge_zero"
[(set (match_operand:SI 0 "register_operand" "=a")
(ge:SI (match_operand:SI 1 "register_operand" "r")
(const_int 0)))]
--
2.30.2
