aboutsummaryrefslogtreecommitdiff
path: root/tcg/tcg.c
diff options
context:
space:
mode:
authorAurelien Jarno <aurelien@aurel32.net>2015-06-04 21:47:08 +0200
committerRichard Henderson <rth@twiddle.net>2015-06-09 06:42:27 -0700
commitc19f47bf5e8fe3dbd10206a52d0e6e348f803933 (patch)
treec443f4c78d7a792731603d1f1d8864b626501fe3 /tcg/tcg.c
parent7e1df267a7e8b39fc0cf1d84d2afc2e88ccbfeac (diff)
tcg: fix dead computation for repeated input arguments
When the same temp is used twice or more as an input argument to a TCG instruction, the dead computation code doesn't recognize the second use as a dead temp. This is because the temp is marked as live in the same loop where dead inputs are checked. The fix is to split the loop in two parts. This avoid emitting a move and using a register for the movcond instruction when used as "move if true" on x86-64. This might bring more improvements on RISC TCG targets which don't have outputs aliased to inputs. Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> Message-Id: <1433447228-29425-3-git-send-email-aurelien@aurel32.net> Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'tcg/tcg.c')
-rw-r--r--tcg/tcg.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 4a6eb26d0a..7e088b1f28 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1387,16 +1387,20 @@ static void tcg_liveness_analysis(TCGContext *s)
memset(dead_temps, 1, s->nb_globals);
}
- /* input args are live */
+ /* record arguments that die in this helper */
for (i = nb_oargs; i < nb_iargs + nb_oargs; i++) {
arg = args[i];
if (arg != TCG_CALL_DUMMY_ARG) {
if (dead_temps[arg]) {
dead_args |= (1 << i);
}
- dead_temps[arg] = 0;
}
}
+ /* input arguments are live for preceeding opcodes */
+ for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
+ arg = args[i];
+ dead_temps[arg] = 0;
+ }
s->op_dead_args[oi] = dead_args;
s->op_sync_args[oi] = sync_args;
}
@@ -1531,12 +1535,16 @@ static void tcg_liveness_analysis(TCGContext *s)
memset(mem_temps, 1, s->nb_globals);
}
- /* input args are live */
+ /* record arguments that die in this opcode */
for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
arg = args[i];
if (dead_temps[arg]) {
dead_args |= (1 << i);
}
+ }
+ /* input arguments are live for preceeding opcodes */
+ for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
+ arg = args[i];
dead_temps[arg] = 0;
}
s->op_dead_args[oi] = dead_args;