Make tcg_constant_folding do copy and constant propagation. It is a
preparational work before actual constant folding.
Signed-off-by: Kirill Batuzov <batuz...@ispras.ru>
---
tcg/optimize.c | 161 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 161 insertions(+), 0 deletions(-)
diff --git a/tcg/optimize.c b/tcg/optimize.c
index 5daf131..7996798 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -31,23 +31,178 @@
#include "qemu-common.h"
#include "tcg-op.h"
+typedef enum {
+ TCG_TEMP_UNDEF = 0,
+ TCG_TEMP_CONST,
+ TCG_TEMP_COPY,
+ TCG_TEMP_ANY
+} tcg_temp_state;
+
+struct tcg_temp_info {
+ tcg_temp_state state;
+ uint16_t num_copies;
+ tcg_target_ulong val;
+};
+
+/* Reset TEMP's state to TCG_TEMP_ANY. If TEMP was a representative of some
+ class of equivalent temp's, a new representative should be chosen in this
+ class. */
+static void reset_temp(struct tcg_temp_info *temps, TCGArg temp, int nb_temps,
+ int nb_globals)
+{
+ int i;
+ TCGArg new_base;
+ if (temps[temp].state == TCG_TEMP_COPY) {
+ temps[temps[temp].val].num_copies--;
+ }
+ if (temps[temp].num_copies > 0) {
+ new_base = (TCGArg)-1;
+ for (i = nb_globals; i < nb_temps; i++) {
+ if (temps[i].state == TCG_TEMP_COPY && temps[i].val == temp) {
+ if (new_base == ((TCGArg)-1)) {
+ new_base = (TCGArg)i;
+ temps[i].state = TCG_TEMP_ANY;
+ temps[i].num_copies = 0;
+ } else {
+ temps[i].val = new_base;
+ temps[new_base].num_copies++;
+ }
+ }
+ }
+ for (i = 0; i < nb_globals; i++) {
+ if (temps[i].state == TCG_TEMP_COPY && temps[i].val == temp) {
+ if (new_base == ((TCGArg)-1)) {
+ temps[i].state = TCG_TEMP_ANY;
+ temps[i].num_copies = 0;
+ } else {
+ temps[i].val = new_base;
+ temps[new_base].num_copies++;
+ }
+ }
+ }
+ }
+ temps[temp].state = TCG_TEMP_ANY;
+ temps[temp].num_copies = 0;
+}
+
+static int op_bits(int op)
+{
+ switch (op) {
+ case INDEX_op_mov_i32:
+ return 32;
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_mov_i64:
+ return 64;
+#endif
+ default:
+ fprintf(stderr, "Unrecognized operation %d in op_bits.\n", op);
+ tcg_abort();
+ }
+}
+
+static int op_to_movi(int op)
+{
+ if (op_bits(op) == 32) {
+ return INDEX_op_movi_i32;
+ }
+#if TCG_TARGET_REG_BITS == 64
+ if (op_bits(op) == 64) {
+ return INDEX_op_movi_i64;
+ }
+#endif
+ tcg_abort();
+}
+
+/* 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)
{
int i, nb_ops, op_index, op, nb_temps, nb_globals;
const TCGOpDef *def;
TCGArg *gen_args;
+ /* 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'
+ representative is kept in VALS' element.
+ If this temp is neither copy nor constant then corresponding VALS'
+ element is unused. */
+ struct tcg_temp_info temps[TCG_MAX_TEMPS];
nb_temps = s->nb_temps;
nb_globals = s->nb_globals;
+ memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
nb_ops = tcg_opc_ptr - gen_opc_buf;
gen_args = args;
for (op_index = 0; op_index < nb_ops; op_index++) {
op = gen_opc_buf[op_index];
def = &tcg_op_defs[op];
+ /* Do copy propagation */
+ if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
+ assert(op != INDEX_op_call);
+ for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
+ if (temps[args[i]].state == TCG_TEMP_COPY
+ && !(def->args_ct[i].ct & TCG_CT_IALIAS)
+ && (def->args_ct[i].ct & TCG_CT_REG)) {
+ args[i] = temps[args[i]].val;
+ }
+ }
+ }
+
+ /* 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. */
switch (op) {
+ case INDEX_op_mov_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_mov_i64:
+#endif
+ if ((temps[args[1]].state == TCG_TEMP_COPY
+ && temps[args[1]].val == args[0])
+ || args[0] == args[1]) {
+ args += 2;
+ gen_opc_buf[op_index] = INDEX_op_nop;
+ break;
+ }
+ if (temps[args[1]].state != TCG_TEMP_CONST) {
+ 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_args[0] = args[0];
+ gen_args[1] = args[1];
+ gen_args += 2;
+ args += 2;
+ break;
+ }
+ /* Source argument is constant. Rewrite the operation and
+ let movi case handle it. */
+ op = op_to_movi(op);
+ gen_opc_buf[op_index] = op;
+ args[1] = temps[args[1]].val;
+ /* fallthrough */
+ case INDEX_op_movi_i32:
+#if TCG_TARGET_REG_BITS == 64
+ case INDEX_op_movi_i64:
+#endif
+ reset_temp(temps, args[0], nb_temps, nb_globals);
+ temps[args[0]].state = TCG_TEMP_CONST;
+ temps[args[0]].val = args[1];
+ assert(temps[args[0]].num_copies == 0);
+ gen_args[0] = args[0];
+ gen_args[1] = args[1];
+ gen_args += 2;
+ args += 2;
+ break;
case INDEX_op_call:
+ for (i = 0; i < nb_globals; i++) {
+ reset_temp(temps, i, nb_temps, nb_globals);
+ }
+ for (i = 0; i < (args[0] >> 16); i++) {
+ reset_temp(temps, args[i + 1], nb_temps, nb_globals);
+ }
i = (args[0] >> 16) + (args[0] & 0xffff) + 3;
while (i) {
*gen_args = *args;
@@ -63,6 +218,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t
*tcg_opc_ptr,
#if TCG_TARGET_REG_BITS == 64
case INDEX_op_brcond_i64:
#endif
+ memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
for (i = 0; i < def->nb_args; i++) {
*gen_args = *args;
args++;
@@ -70,6 +226,11 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t
*tcg_opc_ptr,
}
break;
default:
+ /* Default case: we do know nothing about operation so no
+ propagation is done. We only trash output args. */
+ for (i = 0; i < def->nb_oargs; i++) {
+ reset_temp(temps, args[i], nb_temps, nb_globals);
+ }
for (i = 0; i < def->nb_args; i++) {
gen_args[i] = args[i];
}
--
1.7.4.1
