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target-sh4: improve TLB 

SH4 is using 16-bit instructions which means most of the constants are
loaded through a constant pool at the end of the subroutine. The same
memory page is therefore accessed in exec and read mode.

With the current implementation, a QEMU TLB entry is set to read or
read/write mode after an UTLB search and to exec mode after an ITLB
search, which causes a lot of TLB exceptions to switch from read or
read/write to exec and vice versa.

This patch optimizes that by already setting the QEMU TLB entry in read
or read/write mode when an UTLB entry is copied into ITLB (during an
ITLB miss). This improve the emulation speed by about 14%.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2011-01-09 23:53:45 +01:00
parent c0f809c46a
commit 829a49274f
1 changed files with 44 additions and 21 deletions
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65
target-sh4/helper.c
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@ -280,35 +280,40 @@ static void increment_urc(CPUState * env)
env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
}
/* Find itlb entry - update itlb from utlb if necessary and asked for
/* Copy and utlb entry into itlb
Return entry
*/
static int copy_utlb_entry_itlb(CPUState *env, int utlb)
{
int itlb;
tlb_t * ientry;
itlb = itlb_replacement(env);
ientry = &env->itlb[itlb];
if (ientry->v) {
tlb_flush_page(env, ientry->vpn << 10);
}
*ientry = env->utlb[utlb];
update_itlb_use(env, itlb);
return itlb;
}
/* Find itlb entry
Return entry, MMU_ITLB_MISS, MMU_ITLB_MULTIPLE or MMU_DTLB_MULTIPLE
Update the itlb from utlb if update is not 0
*/
static int find_itlb_entry(CPUState * env, target_ulong address,
int use_asid, int update)
int use_asid)
{
int e, n;
int e;
e = find_tlb_entry(env, address, env->itlb, ITLB_SIZE, use_asid);
if (e == MMU_DTLB_MULTIPLE)
if (e == MMU_DTLB_MULTIPLE) {
e = MMU_ITLB_MULTIPLE;
else if (e == MMU_DTLB_MISS && update) {
e = find_tlb_entry(env, address, env->utlb, UTLB_SIZE, use_asid);
if (e >= 0) {
tlb_t * ientry;
n = itlb_replacement(env);
ientry = &env->itlb[n];
if (ientry->v) {
tlb_flush_page(env, ientry->vpn << 10);
}
*ientry = env->utlb[e];
e = n;
} else if (e == MMU_DTLB_MISS)
e = MMU_ITLB_MISS;
} else if (e == MMU_DTLB_MISS)
} else if (e == MMU_DTLB_MISS) {
e = MMU_ITLB_MISS;
if (e >= 0)
} else if (e >= 0) {
update_itlb_use(env, e);
}
return e;
}
@ -340,13 +345,31 @@ static int get_mmu_address(CPUState * env, target_ulong * physical,
use_asid = (env->mmucr & MMUCR_SV) == 0 || (env->sr & SR_MD) == 0;
if (rw == 2) {
n = find_itlb_entry(env, address, use_asid, 1);
n = find_itlb_entry(env, address, use_asid);
if (n >= 0) {
matching = &env->itlb[n];
if (!(env->sr & SR_MD) && !(matching->pr & 2))
n = MMU_ITLB_VIOLATION;
else
*prot = PAGE_EXEC;
} else {
n = find_utlb_entry(env, address, use_asid);
if (n >= 0) {
n = copy_utlb_entry_itlb(env, n);
matching = &env->itlb[n];
if (!(env->sr & SR_MD) && !(matching->pr & 2)) {
n = MMU_ITLB_VIOLATION;
} else {
*prot = PAGE_READ | PAGE_EXEC;
if ((matching->pr & 1) && matching->d) {
*prot |= PAGE_WRITE;
}
}
} else if (n == MMU_DTLB_MULTIPLE) {
n = MMU_ITLB_MULTIPLE;
} else if (n == MMU_DTLB_MISS) {
n = MMU_ITLB_MISS;
}
}
} else {
n = find_utlb_entry(env, address, use_asid);