Hexagon (target/hexagon) Remove gen_log_predicated_reg_write[_pair]

We assign the instruction destination register to hex_new_value[num]
instead of a TCG temp that gets copied back to hex_new_value[num].

We introduce new functions get_result_gpr[_pair] to facilitate getting
the proper destination register.

Since we preload hex_new_value for predicated instructions, we don't
need the check for slot_cancelled.  So, we call gen_log_reg_write instead.

We update the helper function generation and gen_tcg.h to maintain the
disable-hexagon-idef-parser configuration.

Here is a simple example of the differences in the TCG code generated:

IN:
0x00400094:  0xf900c102 {       if (P0) R2 = and(R0,R1) }

BEFORE
 ---- 00400094
 mov_i32 slot_cancelled,$0x0
 mov_i32 new_r2,r2
 mov_i32 loc2,$0x0
 and_i32 tmp0,p0,$0x1
 brcond_i32 tmp0,$0x0,eq,$L1
 and_i32 tmp0,r0,r1
 mov_i32 loc2,tmp0
 br $L2
 set_label $L1
 or_i32 slot_cancelled,slot_cancelled,$0x8
 set_label $L2
 and_i32 tmp0,slot_cancelled,$0x8
 movcond_i32 new_r2,tmp0,$0x0,loc2,new_r2,eq
 mov_i32 r2,new_r2

AFTER
 ---- 00400094
 mov_i32 slot_cancelled,$0x0
 mov_i32 new_r2,r2
 and_i32 tmp0,p0,$0x1
 brcond_i32 tmp0,$0x0,eq,$L1
 and_i32 tmp0,r0,r1
 mov_i32 new_r2,tmp0
 br $L2
 set_label $L1
 or_i32 slot_cancelled,slot_cancelled,$0x8
 set_label $L2
 mov_i32 r2,new_r2

We'll remove the unnecessary manipulation of slot_cancelled in a
subsequent patch.

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230307025828.1612809-13-tsimpson@quicinc.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/target/hexagon/idef-parser/parser-helpers.c b/target/hexagon/idef-parser/parser-helpers.c
index 4e0c643cae..9720ef4ad1 100644
--- a/target/hexagon/idef-parser/parser-helpers.c
+++ b/target/hexagon/idef-parser/parser-helpers.c
@@ -1668,9 +1668,7 @@ void gen_inst_init_args(Context *c, YYLTYPE *locp)
     for (unsigned i = 0; i < c->inst.init_list->len; i++) {
         HexValue *val = &g_array_index(c->inst.init_list, HexValue, i);
         if (val->type == REGISTER_ARG) {
-            char reg_id[5];
-            reg_compose(c, locp, &val->reg, reg_id);
-            EMIT_HEAD(c, "tcg_gen_movi_i%u(%s, 0);\n", val->bit_width, reg_id);
+            /* Nothing to do here */
         } else if (val->type == PREDICATE) {
             char suffix = val->is_dotnew ? 'N' : 'V';
             EMIT_HEAD(c, "tcg_gen_movi_i%u(P%c%c, 0);\n", val->bit_width,