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Remove code duplication from the dispatchers. Keep the core loop

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in common.
To accomplish that without penalizing the non-profiling dispatcher
we do the stats gathering *after* the jitted code returns to the
dispatcher. For that to work properly, we need to stash away the
instruction adddress before entering the jitted code so we can use
it later. (See also VEX r2208).

Two other tweaks are included here:
(1) For the non-profiling dispatcher it is not necessary to update
    the LR in each iteration. Quite obviously the jitted code cannot
    modify the LR in its iteration because it needs it at the very end
    when it returns. So we move this step out of the core loop.
(2) Move loading the address of VG_(tt_fast) past testing for a changed
    guest state pointer. 


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12044
This commit is contained in:
Florian Krohm 2011-09-25 00:15:54 +00:00
parent 8885c4e740
commit 166c3bcd27
1 changed files with 23 additions and 53 deletions
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76
coregrind/m_dispatch/dispatch-s390x-linux.S
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@ -58,6 +58,9 @@
/* Location of saved guest state pointer */
#define S390_LOC_SAVED_GSP S390_OFFSET_SAVED_GSP(SP)
/* Location of saved R2 register */
#define S390_LOC_SAVED_R2 S390_OFFSET_SAVED_R2(SP)
/*----------------------------------------------------*/
/*--- Preamble (set everything up) ---*/
/*----------------------------------------------------*/
@ -126,6 +129,15 @@ VG_(run_innerloop):
/*----------------------------------------------------*/
run_innerloop__dispatch_unprofiled:
/* Load the link register with the address the jitted code will
return to when it's done executing. The link register is loaded
exactly once per loop. This is safe, because the jitted code
cannot possibly modify the LR. How else would it be able to return
to the location in the LR otherwise? */
basr LR,0
/* Loop begins here */
/* This is the story:
r2 = IA = next guest address
@ -134,11 +146,10 @@ run_innerloop__dispatch_unprofiled:
special value
r15 = stack pointer (as usual)
*/
innermost_loop:
/* Has the guest state pointer been messed with? If yes, exit.
The mess is recognised by r13 containing an odd value. */
tmll %r13,1
larl %r8, VG_(tt_fast)
jne gsp_changed
/* Save the jump address in the guest state */
@ -157,6 +168,7 @@ run_innerloop__dispatch_unprofiled:
which is
offset = ((addr & (VG_TT_FAST_MASK << 1) ) << 3
*/
larl %r8, VG_(tt_fast)
llill %r5,( VG_TT_FAST_MASK << 1) & 0xffff
#if ((( VG_TT_FAST_MASK << 1) & 0xffff0000) >> 16 != 0)
iilh %r5,(( VG_TT_FAST_MASK << 1) & 0xffff0000) >> 16
@ -164,11 +176,6 @@ run_innerloop__dispatch_unprofiled:
ngr %r5,%r2
sllg %r7,%r5,3
/* Set the return address to the beginning of the loop here to
have some instruction between setting r7 and using it as an
address */
larl LR,run_innerloop__dispatch_unprofiled
/* Are we out of timeslice? If yes, defer to scheduler. */
ahi S390_REGNO_DISPATCH_CTR,-1
jz counter_is_zero
@ -190,66 +197,29 @@ run_innerloop__dispatch_unprofiled:
/*----------------------------------------------------*/
run_innerloop__dispatch_profiled:
stg %r2,S390_LOC_SAVED_R2
/* Has the guest state pointer been messed with? If yes, exit.
The mess is recognised by r13 containing an odd value. */
tmll %r13,1
larl %r8, VG_(tt_fast)
jne gsp_changed
/* Load the link register with the address the jitted code will
return to when it's done executing. */
bras LR,innermost_loop
/* Save the jump address in the guest state */
stg %r2,OFFSET_s390x_IA(%r13)
/* Jitted code returns here. Update profile counter for previous IA */
/* Try a fast lookup in the translation cache:
Compute offset (not index) into VT_(tt_fast):
offset = VG_TT_FAST_HASH(addr) * sizeof(FastCacheEntry)
with VG_TT_FAST_HASH(addr) == (addr >> 1) & VG_TT_FAST_MASK
and sizeof(FastCacheEntry) == 16
offset = ((addr >> 1) & VG_TT_FAST_MASK) << 4
which is
offset = ((addr & (VG_TT_FAST_MASK << 1) ) << 3
*/
llill %r5,( VG_TT_FAST_MASK << 1) & 0xffff
#if ((( VG_TT_FAST_MASK << 1) & 0xffff0000) >> 16 != 0)
iilh %r5,(( VG_TT_FAST_MASK << 1) & 0xffff0000) >> 16
#endif
ngr %r5,%r2
sllg %r7,%r5,3
ng %r5,S390_LOC_SAVED_R2
sllg %r7,%r5,2
/* Set the return address to the beginning of the loop here to
have some instruction between setting r7 and using it as an
address */
larl LR,run_innerloop__dispatch_profiled
/* Are we out of timeslice? If yes, defer to scheduler. */
ahi S390_REGNO_DISPATCH_CTR,-1
jz counter_is_zero
lg %r11, 8(%r8,%r7) /* .host */
cg %r2, 0(%r8,%r7) /* next guest address == .guest ? */
jne fast_lookup_failed
/* sizeof(FastCacheEntry) == 16, sizeof(*UInt)==8 */
srlg %r7,%r7,1
/* we got a hit: VG_(tt_fastN) is guaranteed to point to count */
/* Increment bb profile counter */
larl %r8, VG_(tt_fastN)
/* increment bb profile counter */
lg %r9,0(%r8,%r7)
l %r10,0(%r9)
ahi %r10,1
st %r10,0(%r9)
/* Found a match. Call .host.
r11 is an address. There we will find the instrumented client code.
That code may modify the guest state register r13. The client code
will return to the beginning of this loop start by issuing br LR.
We can simply branch to the host code */
br %r11
j run_innerloop__dispatch_profiled
/*----------------------------------------------------*/
/*--- exit points ---*/