On Mon, Feb 04, 2002 at 04:46:07PM +0000, Dominic Sweetman wrote:
>
> H . J . Lu (hjl@lucon.org) writes:
>
> > I can change glibc not to use branch-likely without using nop. But it
> > may require one or two instructions outside of the loop. Should I do
> > it given what we know now?
>
> I would not recommend using "branch likely" in assembler coding, if
> that's what you're asking.
>
Here is a patch to remove branch likely. But I couldn't find a way
not to fill the delay slot with nop. BTW, is that safe to remove
".set noreorder"?
H.J.
---
2002-02-04 H.J. Lu <hjl@gnu.org>
* sysdeps/mips/pspinlock.c (__pthread_spin_lock): Not use
branch likely.
* sysdeps/mips/pt-machine.h (testandset): Liekwise.
(__compare_and_swap): Liekwise.
2002-02-04 H.J. Lu <hjl@gnu.org>
* sysdeps/mips/atomicity.h (exchange_and_add): Not use branch
likely.
(atomic_add): Likewise.
(compare_and_swap): Likewise.
* sysdeps/unix/sysv/linux/mips/sys/tas.h (_test_and_set):
Likewise.
--- libc/linuxthreads/sysdeps/mips/pspinlock.c.llsc Mon Feb 4 13:45:01 2002
+++ libc/linuxthreads/sysdeps/mips/pspinlock.c Mon Feb 4 17:09:02 2002
@@ -40,7 +40,7 @@ __pthread_spin_lock (pthread_spinlock_t
"bnez %1,1b\n\t"
" li %2,1\n\t"
"sc %2,%0\n\t"
- "beqzl %2,1b\n\t"
+ "beqz %2,1b\n\t"
" ll %1,%3\n\t"
".set pop"
: "=m" (*lock), "=&r" (tmp1), "=&r" (tmp2)
--- libc/linuxthreads/sysdeps/mips/pt-machine.h.llsc Mon Feb 4 13:45:01 2002
+++ libc/linuxthreads/sysdeps/mips/pt-machine.h Mon Feb 4 17:09:36 2002
@@ -66,7 +66,7 @@ __compare_and_swap (long int *p, long in
" move %0,$0\n\t"
"move %0,%4\n\t"
"sc %0,%2\n\t"
- "beqzl %0,1b\n\t"
+ "beqz %0,1b\n\t"
" ll %1,%5\n\t"
".set pop\n"
"2:\n\t"
--- libc/sysdeps/mips/atomicity.h.llsc Mon Feb 4 13:45:18 2002
+++ libc/sysdeps/mips/atomicity.h Mon Feb 4 17:14:48 2002
@@ -32,15 +32,15 @@ exchange_and_add (volatile uint32_t *mem
int result, tmp;
__asm__ __volatile__
- ("/* Inline exchange & add */\n\t"
+ ("/* Inline exchange & add */\n"
+ "1:\n"
"ll %0,%3\n"
- "1:\n\t"
"addu %1,%4,%0\n\t"
"sc %1,%2\n\t"
".set push\n\t"
".set noreorder\n\t"
- "beqzl %1,1b\n\t"
- " ll %0,%3\n\t"
+ "beqz %1,1b\n\t"
+ " nop\n\t"
".set pop\n\t"
"/* End exchange & add */"
: "=&r"(result), "=&r"(tmp), "=m"(*mem)
@@ -57,15 +57,15 @@ atomic_add (volatile uint32_t *mem, int
int result;
__asm__ __volatile__
- ("/* Inline atomic add */\n\t"
- "ll %0,%2\n"
+ ("/* Inline atomic add */\n"
"1:\n\t"
+ "ll %0,%2\n"
"addu %0,%3,%0\n\t"
"sc %0,%1\n\t"
".set push\n\t"
".set noreorder\n\t"
- "beqzl %0,1b\n\t"
- " ll %0,%2\n\t"
+ "beqz %0,1b\n\t"
+ " nop\n\t"
".set pop\n\t"
"/* End atomic add */"
: "=&r"(result), "=m"(*mem)
@@ -89,7 +89,7 @@ compare_and_swap (volatile long int *p,
" move %0,$0\n\t"
"move %0,%4\n\t"
"sc %0,%2\n\t"
- "beqzl %0,1b\n\t"
+ "beqz %0,1b\n\t"
" ll %1,%5\n\t"
".set pop\n"
"2:\n\t"
--- libc/sysdeps/unix/sysv/linux/mips/sys/tas.h.llsc Mon Feb 4 13:45:28 2002
+++ libc/sysdeps/unix/sysv/linux/mips/sys/tas.h Mon Feb 4 17:19:06 2002
@@ -42,16 +42,16 @@ _test_and_set (int *p, int v) __THROW
int r, t;
__asm__ __volatile__
- ("/* Inline test and set */\n\t"
- "ll %0,%3\n"
+ ("/* Inline test and set */\n"
"1:\n\t"
+ "ll %0,%3\n"
".set push\n\t"
".set noreorder\n\t"
"beq %0,%4,2f\n\t"
" move %1,%4\n\t"
"sc %1,%2\n\t"
- "beqzl %1,1b\n\t"
- " ll %0,%3\n\t"
+ "beqz %1,1b\n\t"
+ " nop\n\t"
".set pop\n"
"2:\n\t"
"/* End test and set */"
