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| author | Daniel Hellstrom <daniel@gaisler.com> | 2014-05-26 15:22:12 +0200 |
|---|---|---|
| committer | Daniel Hellstrom <daniel@gaisler.com> | 2014-05-28 17:33:22 +0200 |
| commit | d6f1ec91b6fd074e3a2b15f7ca8b2a8c73a39484 (patch) | |
| tree | 811725cdfc49acf88fa10febf6c60965225c242b /c/src/lib/libbsp/sparc/shared/start/start.S | |
| parent | LEON3: coding style clean bsp_irq_fixup() (diff) | |
| download | rtems-d6f1ec91b6fd074e3a2b15f7ca8b2a8c73a39484.tar.bz2 | |
SPARC: syscall optimizations and PSR-write fix
The last optimization missed was incorrect in regards to
PSR write instruction delay must be 3 instructions.
New optimizations:
* align to 32-byte cache line.
* rearrange code into three "blocks" of 4 instructions that
is executed by syscall 2 and 3. This is to optimize for
16/32 byte cache lines.
* use delay-slot instruction in trap table to reduce by one
instruction.
* use the fact that "wr %PSR" implements XOR to reduce by
one instruction.
Diffstat (limited to 'c/src/lib/libbsp/sparc/shared/start/start.S')
| -rw-r--r-- | c/src/lib/libbsp/sparc/shared/start/start.S | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/c/src/lib/libbsp/sparc/shared/start/start.S b/c/src/lib/libbsp/sparc/shared/start/start.S index 65dd559376..070387ff1e 100644 --- a/c/src/lib/libbsp/sparc/shared/start/start.S +++ b/c/src/lib/libbsp/sparc/shared/start/start.S @@ -33,6 +33,15 @@ nop; /* + * System call optimized trap table entry + */ +#define SYSCALL_TRAP(_vector, _handler) \ + mov %psr, %l0 ; \ + sethi %hi(_handler), %l4 ; \ + jmp %l4+%lo(_handler); \ + subcc %g1, 3, %g0; ! prepare for syscall 3 check + +/* * Software trap. Treat as BAD_TRAP for the time being... */ @@ -156,7 +165,7 @@ SYM(CLOCK_SPEED): * installed before. */ - TRAP( 0x80, SYM(syscall) ); ! 80 syscall SW trap + SYSCALL_TRAP( 0x80, SYM(syscall) ); ! 80 syscall SW trap SOFT_TRAP; SOFT_TRAP; ! 81 - 82 TRAP( 0x83, SYM(window_flush_trap_handler) ); ! 83 flush windows SW trap |