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SPARC: window overflow optimization

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I see no need for waiting the 3 instruction delay for wim to be
written in this case, since the STD after does not depend on WIM
This commit is contained in:
Daniel Hellstrom
2014-05-27 11:15:46 +02:00
parent e7e92da52e
commit 348d1812ba
2 changed files with 19 additions and 17 deletions
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11
c/src/lib/libbsp/sparc/shared/start/start.S
View File

@@ -41,6 +41,15 @@
jmp %l4+%lo(_handler); \
subcc %g1, 3, %g0; ! prepare for syscall 3 check
/*
* Window Overflow optimized trap table entry
*/
#define WOTRAP(_vector, _handler) \
sethi %hi(_handler), %l4; \
jmp %l4+%lo(_handler); \
save; \
nop
/*
* Software trap. Treat as BAD_TRAP for the time being...
*/
@@ -72,7 +81,7 @@ SYM(trap_table):
BAD_TRAP; ! 02 illegal instruction
BAD_TRAP; ! 03 privileged instruction
BAD_TRAP; ! 04 fp disabled
TRAP( 5, SYM(window_overflow_trap_handler) ); ! 05 window overflow
WOTRAP(5, SYM(window_overflow_trap_handler)); ! 05 window overflow
TRAP( 6, SYM(window_underflow_trap_handler) );! 06 window underflow
BAD_TRAP; ! 07 memory address not aligned
BAD_TRAP; ! 08 fp exception

25
c/src/lib/libcpu/sparc/reg_win/window.S
View File

@@ -29,9 +29,8 @@
*
* On entry:
*
* l0 = psr (from trap table)
* l1 = pc
* l2 = npc
* prev regwin l1 = pc
* prev regwin l2 = npc
*/
PUBLIC(window_overflow_trap_handler)
@@ -51,29 +50,23 @@ SYM(window_overflow_trap_handler):
* register will result in the local register set changing.
*/
mov %wim, %l3 ! l3 = WIM
mov %g1, %l7 ! save g1
srl %l3, 1, %g1 ! g1 = WIM >> 1
sll %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1 , %l4
! l4 = WIM << (Number Windows - 1)
or %l4, %g1, %g1 ! g1 = (WIM >> 1) |
! (WIM << (Number Windows - 1))
save ! Get into window to be saved.
mov %g1, %wim ! load new WIM
nop; nop; nop ! 3 slot delay
std %l0, [%sp + 0x00] ! save local register set
std %l2, [%sp + 0x08]
mov %wim, %l3
sll %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1 , %l2
! l2 = WIM << (Number Windows - 1)
std %l4, [%sp + 0x10]
std %l6, [%sp + 0x18]
srl %l3, 1, %l3 ! l3 = WIM >> 1
wr %l3, %l2, %wim ! WIM = (WIM >> 1) ^
! (WIM << (Number Windows - 1))
std %i0, [%sp + 0x20] ! save input register set
std %i2, [%sp + 0x28]
std %i4, [%sp + 0x30]
std %i6, [%sp + 0x38]
restore ! Go back to trap window.
mov %l7, %g1 ! restore g1
jmp %l1 ! Re-execute save.
rett %l2
rett %l2
/*
* Window underflow trap handler.