Perform actual constant folding for ADD, SUB and MUL operations.
Signed-off-by: Kirill Batuzov <batuz...@ispras.ru>
---
tcg/optimize.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 156 insertions(+), 0 deletions(-)
diff --git a/tcg/optimize.c b/tcg/optimize.c
index 7996798..29da6fa 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -89,9 +89,15 @@ static int op_bits(int op)
{
switch (op) {
case INDEX_op_mov_i32:
+ case INDEX_op_add_i32:
+ case INDEX_op_sub_i32:
+ case INDEX_op_mul_i32:
return 32;
#if TCG_TARGET_REG_BITS == 64
case INDEX_op_mov_i64:
+ case INDEX_op_add_i64:
+ case INDEX_op_sub_i64:
+ case INDEX_op_mul_i64:
return 64;
#endif
default:
@@ -113,6 +119,58 @@ static int op_to_movi(int op)
tcg_abort();
}
+static int op_to_mov(int op)
+{
+ if (op_bits(op) == 32) {
+ return INDEX_op_mov_i32;
+ }
+#if TCG_TARGET_REG_BITS == 64
+ if (op_bits(op) == 64) {
+ return INDEX_op_mov_i64;
+ }
+#endif
+ tcg_abort();
+}
+
+static TCGArg do_constant_folding_2(int op, TCGArg x, TCGArg y)
+{
+ switch (op) {
+ case INDEX_op_add_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_add_i64:
+#endif
+ return x + y;
+
+ case INDEX_op_sub_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_sub_i64:
+#endif
+ return x - y;
+
+ case INDEX_op_mul_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_mul_i64:
+#endif
+ return x * y;
+
+ default:
+ fprintf(stderr,
+ "Unrecognized operation %d in do_constant_folding.\n", op);
+ tcg_abort();
+ }
+}
+
+static TCGArg do_constant_folding(int op, TCGArg x, TCGArg y)
+{
+ TCGArg res = do_constant_folding_2(op, x, y);
+#if TCG_TARGET_REG_BITS == 64
+ if (op_bits(op) == 32) {
+ res &= 0xffffffff;
+ }
+#endif
+ return res;
+}
+
/* Propagate constants and copies, fold constant expressions. */
static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
TCGArg *args, TCGOpDef *tcg_op_defs)
@@ -120,6 +178,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t
*tcg_opc_ptr,
int i, nb_ops, op_index, op, nb_temps, nb_globals;
const TCGOpDef *def;
TCGArg *gen_args;
+ TCGArg tmp;
/* Array VALS has an element for each temp.
If this temp holds a constant then its value is kept in VALS' element.
If this temp is a copy of other ones then this equivalence class'
@@ -149,6 +208,72 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
uint16_t *tcg_opc_ptr,
}
}
+ /* Simplify expression if possible. */
+ switch (op) {
+ case INDEX_op_add_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_add_i64:
+#endif
+ if (temps[args[1]].state == TCG_TEMP_CONST) {
+ /* 0 + x == x + 0 */
+ tmp = args[1];
+ args[1] = args[2];
+ args[2] = tmp;
+ }
+ /* Fallthrough */
+ case INDEX_op_sub_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_sub_i64:
+#endif
+ if (temps[args[1]].state == TCG_TEMP_CONST) {
+ /* Proceed with possible constant folding. */
+ break;
+ }
+ if (temps[args[2]].state == TCG_TEMP_CONST
+ && temps[args[2]].val == 0) {
+ if ((temps[args[0]].state == TCG_TEMP_COPY
+ && temps[args[0]].val == args[1])
+ || args[0] == args[1]) {
+ args += 3;
+ gen_opc_buf[op_index] = INDEX_op_nop;
+ } else {
+ reset_temp(temps, args[0], nb_temps, nb_globals);
+ if (args[1] >= s->nb_globals) {
+ temps[args[0]].state = TCG_TEMP_COPY;
+ temps[args[0]].val = args[1];
+ temps[args[1]].num_copies++;
+ }
+ gen_opc_buf[op_index] = op_to_mov(op);
+ gen_args[0] = args[0];
+ gen_args[1] = args[1];
+ gen_args += 2;
+ args += 3;
+ }
+ continue;
+ }
+ break;
+ case INDEX_op_mul_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_mul_i64:
+#endif
+ if ((temps[args[1]].state == TCG_TEMP_CONST
+ && temps[args[1]].val == 0)
+ || (temps[args[2]].state == TCG_TEMP_CONST
+ && temps[args[2]].val == 0)) {
+ reset_temp(temps, args[0], nb_temps, nb_globals);
+ temps[args[0]].state = TCG_TEMP_CONST;
+ temps[args[0]].val = 0;
+ assert(temps[args[0]].num_copies == 0);
+ gen_opc_buf[op_index] = op_to_movi(op);
+ gen_args[0] = args[0];
+ gen_args[1] = 0;
+ args += 3;
+ gen_args += 2;
+ continue;
+ }
+ break;
+ }
+
/* Propagate constants through copy operations and do constant
folding. Constants will be substituted to arguments by register
allocator where needed and possible. Also detect copies. */
@@ -196,6 +321,37 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
uint16_t *tcg_opc_ptr,
gen_args += 2;
args += 2;
break;
+ case INDEX_op_add_i32:
+ case INDEX_op_sub_i32:
+ case INDEX_op_mul_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_add_i64:
+ case INDEX_op_sub_i64:
+ case INDEX_op_mul_i64:
+#endif
+ if (temps[args[1]].state == TCG_TEMP_CONST
+ && temps[args[2]].state == TCG_TEMP_CONST) {
+ gen_opc_buf[op_index] = op_to_movi(op);
+ gen_args[0] = args[0];
+ gen_args[1] =
+ do_constant_folding(op, temps[args[1]].val,
+ temps[args[2]].val);
+ reset_temp(temps, gen_args[0], nb_temps, nb_globals);
+ temps[gen_args[0]].state = TCG_TEMP_CONST;
+ temps[gen_args[0]].val = gen_args[1];
+ assert(temps[gen_args[0]].num_copies == 0);
+ gen_args += 2;
+ args += 3;
+ break;
+ } else {
+ reset_temp(temps, args[0], nb_temps, nb_globals);
+ gen_args[0] = args[0];
+ gen_args[1] = args[1];
+ gen_args[2] = args[2];
+ gen_args += 3;
+ args += 3;
+ break;
+ }
case INDEX_op_call:
for (i = 0; i < nb_globals; i++) {
reset_temp(temps, i, nb_temps, nb_globals);
--
1.7.4.1
