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[Qemu-devel] [PATCH 02/17] tcg/optimize: optimize temps tracking
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH 02/17] tcg/optimize: optimize temps tracking |
Date: |
Mon, 17 Aug 2015 12:38:25 -0700 |
From: Aurelien Jarno <address@hidden>
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;
--
2.4.3
- [Qemu-devel] [PATCH 00/17] queued tcg improvements, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 01/17] tcg/optimize: fix constant signedness, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 02/17] tcg/optimize: optimize temps tracking,
Richard Henderson <=
- [Qemu-devel] [PATCH 04/17] tcg/optimize: track const/copy status separately, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 05/17] tcg/optimize: allow constant to have copies, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 03/17] tcg/optimize: add temp_is_const and temp_is_copy functions, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 06/17] tcg: rename trunc_shr_i32 into trunc_shr_i64_i32, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 07/17] tcg: don't abuse TCG type in tcg_gen_trunc_shr_i64_i32, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 14/17] tcg/i386: use softmmu fast path for unaligned accesses, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 15/17] tcg/ppc: Improve unaligned load/store handling on 64-bit backend, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 12/17] tcg: Split trunc_shr_i32 opcode into extr[lh]_i64_i32, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 16/17] tcg/s390: Use softmmu fast path for unaligned accesses, Richard Henderson, 2015/08/17
- [Qemu-devel] [PATCH 11/17] tcg: update README about size changing ops, Richard Henderson, 2015/08/17