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[Qemu-devel] [PATCH v2 for-2.5 03/12] tcg/optimize: optimize temps track
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] [PATCH v2 for-2.5 03/12] tcg/optimize: optimize temps tracking |
Date: |
Mon, 27 Jul 2015 12:55:59 +0200 |
The tcg_temp_info structure uses 24 bytes per temp. Now that we emulate
vector registers on most guests, it's not uncommon to have more than 100
used temps. This means we have initialize more than 2kB at least twice
per TB, often more when there is a few goto_tb.
Instead used a TCGTempSet bit array to track which temps are in used in
the current basic block. This means there are only around 16 bytes to
initialize.
This improves the boot time of a MIPS guest on an x86-64 host by around
7% and moves out tcg_optimize from the the top of the profiler list.
Cc: Richard Henderson <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
tcg/optimize.c | 36 +++++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)
diff --git a/tcg/optimize.c b/tcg/optimize.c
index cd0e793..425c14b 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -50,6 +50,7 @@ struct tcg_temp_info {
};
static struct tcg_temp_info temps[TCG_MAX_TEMPS];
+static TCGTempSet temps_used;
/* Reset TEMP's state to TCG_TEMP_UNDEF. If TEMP only had one copy, remove
the copy flag from the left temp. */
@@ -67,6 +68,22 @@ static void reset_temp(TCGArg temp)
temps[temp].mask = -1;
}
+/* Reset all temporaries, given that there are NB_TEMPS of them. */
+static void reset_all_temps(int nb_temps)
+{
+ bitmap_zero(temps_used.l, nb_temps);
+}
+
+/* Initialize and activate a temporary. */
+static void init_temp_info(TCGArg temp)
+{
+ if (!test_bit(temp, temps_used.l)) {
+ temps[temp].state = TCG_TEMP_UNDEF;
+ temps[temp].mask = -1;
+ set_bit(temp, temps_used.l);
+ }
+}
+
static TCGOp *insert_op_before(TCGContext *s, TCGOp *old_op,
TCGOpcode opc, int nargs)
{
@@ -98,16 +115,6 @@ static TCGOp *insert_op_before(TCGContext *s, TCGOp *old_op,
return new_op;
}
-/* Reset all temporaries, given that there are NB_TEMPS of them. */
-static void reset_all_temps(int nb_temps)
-{
- int i;
- for (i = 0; i < nb_temps; i++) {
- temps[i].state = TCG_TEMP_UNDEF;
- temps[i].mask = -1;
- }
-}
-
static int op_bits(TCGOpcode op)
{
const TCGOpDef *def = &tcg_op_defs[op];
@@ -606,6 +613,11 @@ void tcg_optimize(TCGContext *s)
nb_iargs = def->nb_iargs;
}
+ /* Initialize the temps that are going to be used */
+ for (i = 0; i < nb_oargs + nb_iargs; i++) {
+ init_temp_info(args[i]);
+ }
+
/* Do copy propagation */
for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
if (temps[args[i]].state == TCG_TEMP_COPY) {
@@ -1299,7 +1311,9 @@ void tcg_optimize(TCGContext *s)
if (!(args[nb_oargs + nb_iargs + 1]
& (TCG_CALL_NO_READ_GLOBALS | TCG_CALL_NO_WRITE_GLOBALS))) {
for (i = 0; i < nb_globals; i++) {
- reset_temp(i);
+ if (test_bit(i, temps_used.l)) {
+ reset_temp(i);
+ }
}
}
goto do_reset_output;
--
2.1.4
- [Qemu-devel] [PATCH v2 for-2.5 00/12] tcg: improve optimizer, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 08/12] tcg: don't abuse TCG type in tcg_gen_trunc_shr_i64_i32, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 12/12] tcg: update README about size changing ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 10/12] tcg/optimize: add optimizations for ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 03/12] tcg/optimize: optimize temps tracking,
Aurelien Jarno <=
- [Qemu-devel] [PATCH v2 for-2.5 11/12] tcg/optimize: do not remember garbage high bits for 32-bit ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 07/12] tcg: rename trunc_shr_i32 into trunc_shr_i64_i32, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 09/12] tcg: implement real ext_i32_i64 and extu_i32_i64 ops, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 04/12] tcg/optimize: add temp_is_const and temp_is_copy functions, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH for-2.4 02/12] tcg: mark temps as mem_coherent = 0 for mov with a constant, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH for-2.4 01/12] tcg: correctly mark dead inputs for mov with a constant, Aurelien Jarno, 2015/07/27
- [Qemu-devel] [PATCH v2 for-2.5 06/12] tcg/optimize: allow constant to have copies, Aurelien Jarno, 2015/07/27