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Re: PATCH: Fix ll/sc for mips (take 3)

To: Dominic Sweetman <dom@algor.co.uk>
Subject: Re: PATCH: Fix ll/sc for mips (take 3)
From: "H . J . Lu" <hjl@lucon.org>
Date: Mon, 4 Feb 2002 17:28:57 -0800
Cc: GNU C Library <libc-alpha@sources.redhat.com>, linux-mips@oss.sgi.com
In-reply-to: <15454.47823.837119.847975@gladsmuir.algor.co.uk>; from dom@algor.co.uk on Mon, Feb 04, 2002 at 04:46:07PM +0000
References: <20020201180126.A23740@nevyn.them.org> <20020201151513.A15913@lucon.org> <20020201222657.A13339@nevyn.them.org> <1012676003.1563.6.camel@xyzzy.stargate.net> <20020202120354.A1522@lucon.org> <mailpost.1012680250.7159@news-sj1-1> <yov5ofj65elj.fsf@broadcom.com> <15454.22661.855423.532827@gladsmuir.algor.co.uk> <20020204083115.C13384@lucon.org> <15454.47823.837119.847975@gladsmuir.algor.co.uk>
Sender: owner-linux-mips@oss.sgi.com
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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 */"

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