Get rid of a bunch of loads in the arm dispatcher inner loops, and
make some attempt to schedule for Cortex-A8. Improves overall IPC
for none running perf/bz2.c "-O" from 0.879 to 0.925.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11780 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/m_dispatch/dispatch-arm-linux.S b/coregrind/m_dispatch/dispatch-arm-linux.S
index f67aeef..20b13fa 100644
--- a/coregrind/m_dispatch/dispatch-arm-linux.S
+++ b/coregrind/m_dispatch/dispatch-arm-linux.S
@@ -75,6 +75,9 @@
/*--- NO-PROFILING (standard) dispatcher ---*/
/*----------------------------------------------------*/
+/* Pairing of insns below is my guesstimate of how dual dispatch would
+ work on an A8. JRS, 2011-May-28 */
+
.global VG_(run_innerloop__dispatch_unprofiled)
VG_(run_innerloop__dispatch_unprofiled):
@@ -83,35 +86,47 @@
/* Has the guest state pointer been messed with? If yes, exit. */
ldr r1, [sp, #0]
+ movw r3, #:lower16:VG_(dispatch_ctr)
+
cmp r8, r1
+ movt r3, #:upper16:VG_(dispatch_ctr)
+
bne gsp_changed
/* save the jump address in the guest state */
str r0, [r8, #OFFSET_arm_R15T]
/* Are we out of timeslice? If yes, defer to scheduler. */
- ldr r1, =VG_(dispatch_ctr)
- ldr r2, [r1]
+ ldr r2, [r3]
+
subs r2, r2, #1
- str r2, [r1]
+
+ str r2, [r3]
+
beq counter_is_zero
/* try a fast lookup in the translation cache */
- // r0 = next guest, r1,r2,r3 scratch
- ldr r1, =VG_TT_FAST_MASK // r1 = VG_TT_FAST_MASK
+ // r0 = next guest, r1,r2,r3,r4 scratch
+ movw r1, #VG_TT_FAST_MASK // r1 = VG_TT_FAST_MASK
+ movw r4, #:lower16:VG_(tt_fast)
+
and r2, r1, r0, LSR #1 // r2 = entry #
- ldr r1, =VG_(tt_fast) // r1 = &tt_fast[0]
- add r1, r1, r2, LSL #3 // r1 = &tt_fast[entry#]
- ldr r3, [r1, #0] /* .guest */
- ldr r1, [r1, #4] /* .host */
- cmp r0, r3
+ movt r4, #:upper16:VG_(tt_fast) // r4 = &VG_(tt_fast)
+
+ add r1, r4, r2, LSL #3 // r1 = &tt_fast[entry#]
+
+ ldrd r4, r5, [r1, #0] // r4 = .guest, r5 = .host
+
+ cmp r4, r0
+
bne fast_lookup_failed
- // r1: live, next-host r8: live, gsp
- // r2: entry # (but not live)
- // r0, r3: dead
+ // r5: next-host r8: live, gsp
+ // r4: next-guest
+ // r2: entry #
+ // LIVE: r5, r8; all others dead
/* Found a match. Jump to .host. */
- blx r1
+ blx r5
b VG_(run_innerloop__dispatch_unprofiled)
.ltorg
/*NOTREACHED*/
@@ -128,42 +143,55 @@
/* Has the guest state pointer been messed with? If yes, exit. */
ldr r1, [sp, #0]
+ movw r3, #:lower16:VG_(dispatch_ctr)
+
cmp r8, r1
+ movt r3, #:upper16:VG_(dispatch_ctr)
+
bne gsp_changed
/* save the jump address in the guest state */
str r0, [r8, #OFFSET_arm_R15T]
/* Are we out of timeslice? If yes, defer to scheduler. */
- ldr r1, =VG_(dispatch_ctr)
- ldr r2, [r1]
+ ldr r2, [r3]
+
subs r2, r2, #1
- str r2, [r1]
+
+ str r2, [r3]
+
beq counter_is_zero
/* try a fast lookup in the translation cache */
- // r0 = next guest, r1,r2,r3 scratch
- ldr r1, =VG_TT_FAST_MASK // r1 = VG_TT_FAST_MASK
+ // r0 = next guest, r1,r2,r3,r4 scratch
+ movw r1, #VG_TT_FAST_MASK // r1 = VG_TT_FAST_MASK
+ movw r4, #:lower16:VG_(tt_fast)
+
and r2, r1, r0, LSR #1 // r2 = entry #
- ldr r1, =VG_(tt_fast) // r1 = &tt_fast[0]
- add r1, r1, r2, LSL #3 // r1 = &tt_fast[entry#]
- ldr r3, [r1, #0] /* .guest */
- ldr r1, [r1, #4] /* .host */
- cmp r0, r3
+ movt r4, #:upper16:VG_(tt_fast) // r4 = &VG_(tt_fast)
+
+ add r1, r4, r2, LSL #3 // r1 = &tt_fast[entry#]
+
+ ldrd r4, r5, [r1, #0] // r4 = .guest, r5 = .host
+
+ cmp r4, r0
+
bne fast_lookup_failed
- // r1: live, next-host r8: live, gsp
- // r2: entry # (but not live)
- // r0, r3: dead
+ // r5: next-host r8: live, gsp
+ // r4: next-guest
+ // r2: entry #
+ // LIVE: r5, r8; all others dead
/* increment bb profile counter */
- ldr r0, =VG_(tt_fastN) // r0 = &tt_fastN[0]
- ldr r0, [r0, r2, LSL #2] // r0 = tt_fast[entry #]
- ldr r3, [r0] // *r0 ++
+ movw r0, #:lower16:VG_(tt_fastN)
+ movt r0, #:upper16:VG_(tt_fastN) // r0 = &tt_fastN[0]
+ ldr r0, [r0, r2, LSL #2] // r0 = tt_fast[entry #]
+ ldr r3, [r0] // *r0 ++
add r3, r3, #1
str r3, [r0]
/* Found a match. Jump to .host. */
- blx r1
+ blx r5
b VG_(run_innerloop__dispatch_profiled)
/*NOTREACHED*/
