SH: makecontext: Improve understandability.

diff --git a/ChangeLog b/ChangeLog
index 455c3ccec8ece6b3d34c4c2954499e825a199946..3ebc2aba18cddbde383285944b55bcca6a284d69 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2012-06-23  Thomas Schwinge  <thomas@codesourcery.com>
+
+       * sysdeps/unix/sysv/linux/sh/makecontext.S: Add comments and give more
+       meaningful names to some local labels.
+
 2012-06-22  Nobuhiro Iwamatsu  <iwamatsu@nigauri.org>
            Kaz Kojima  <kkojima@rr.iij4u.or.jp>
 

diff --git a/sysdeps/unix/sysv/linux/sh/makecontext.S b/sysdeps/unix/sysv/linux/sh/makecontext.S
index 0a9e0795459c8e6414cebce01a8a04d659906dc8..9e1358dba6baaced1fde1c339ee2b22dd98d42f8 100644 (file)
--- a/sysdeps/unix/sysv/linux/sh/makecontext.S
+++ b/sysdeps/unix/sysv/linux/sh/makecontext.S
@@ -1,5 +1,5 @@
 /* Create new context.
-   Copyright (C) 2005 Free Software Foundation, Inc.
+   Copyright (C) 2005-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -33,44 +33,44 @@
        .align  5
 ENTRY(__makecontext)
        mov     #4, r3
-       mov.l   @(oSS_SP,r4), r1
-       mov.l   @(oSS_SIZE,r4), r2
-       add     r1, r2
-       cmp/gt  r6, r3
+       mov.l   @(oSS_SP,r4), r1        /* r1 <- ucb->stack_base */
+       mov.l   @(oSS_SIZE,r4), r2      /* r2 <- ucb->stack_size */
+       add     r1, r2                  /* r2 <- stack_top */
+       cmp/gt  r6, r3                  /* 4 > argc? */
        bf/s    1f
-        shlr2  r2
+        shlr2  r2                      /* r2 <- stack_top / 4 */
        sub     r6, r2
        add     r3, r2
 1:
-       shll2   r2
+       shll2   r2              /* r2 <- stack_top - ((argc > 4) ? 4 * (argc - 4) : 0 */
        mov     #oR15, r0
        mov.l   @(oLINK,r4), r1
-       mov.l   r2, @(r0,r4)
-       mov.l   r1, @(oR8,r4)
+       mov.l   r2, @(r0,r4)    /* ucp->r15 <- r2 */
+       mov.l   r1, @(oR8,r4)   /* ucp->r8 <- ucp->uc_link */
        mov     #oPC, r0
-       mov.l   r5, @(r0,r4)
+       mov.l   r5, @(r0,r4)    /* ucp->PC <- func */
 
-       cmp/pl  r6
+       cmp/pl  r6              /* argc > 0? */
        bf/s    .L1
         dt     r6
-       mov.l   r7, @(oR4,r4)
-       cmp/pl  r6
+       mov.l   r7, @(oR4,r4)   /* ucp->r4 <- argv[0] */
+       cmp/pl  r6              /* argc > 1? */
        bf/s    .L1
         dt     r6
        mov.l   @(0,r15), r1
-       mov.l   r1, @(oR5,r4)
-       cmp/pl  r6
+       mov.l   r1, @(oR5,r4)   /* ucp->r5 <- argv[1] */
+       cmp/pl  r6              /* argc > 2? */
        bf/s    .L1
         dt     r6
        mov.l   @(4,r15), r1
-       mov.l   r1, @(oR6,r4)
-       cmp/pl  r6
+       mov.l   r1, @(oR6,r4)   /* ucp->r6 <- argv[2] */
+       cmp/pl  r6              /* argc > 3? */
        bf/s    .L1
         dt     r6
        mov.l   @(8,r15), r1
-       mov.l   r1, @(oR7,r4)
+       mov.l   r1, @(oR7,r4)   /* ucp->r7 <- argv[3] */
        mov     #12,r0
-.L0:
+.L0:                           /* Save remaining argv[] on the stack.  */
        cmp/pl  r6
        bf/s    .L1
         dt     r6
@@ -87,7 +87,7 @@ ENTRY(__makecontext)
 #endif
        add     #oPR, r4
        rts
-        mov.l  r0, @r4
+        mov.l  r0, @r4         /* ucp->pr <- exitcode */
 #ifndef PIC
        .align  2
 .L2:
@@ -97,24 +97,24 @@ ENTRY(__makecontext)
 
        .align  5
 .Lexitcode:
-       tst     r8, r8
+       tst     r8, r8          /* ucb->uc_link == NULL? */
        bt/s    2f
-        mov    r8, r4
+        mov    r8, r4          /* r4 <- ucb->uc_link */
 #ifdef PIC
        mova    .Lgot, r0
        mov.l   .Lgot, r12
        add     r0, r12
-       mov.l   .L3, r1
+       mov.l   .Lsetcontext, r1
        bsrf    r1
 .LPCS0:
         nop
 #else
-       mov.l   .L3, r1
+       mov.l   .Lsetcontext, r1
        jsr     @r1
         nop
 #endif
 2:
-       mov.l   .L4, r1
+       mov.l   .Lexit, r1
 #ifdef PIC
        add     r12, r1
 #endif
@@ -128,14 +128,14 @@ ENTRY(__makecontext)
 #ifdef PIC
 .Lgot:
        .long   _GLOBAL_OFFSET_TABLE_
-.L3:
+.Lsetcontext:
        .long   __setcontext@PLT-(.LPCS0+2-(.))
-.L4:
+.Lexit:
        .long   HIDDEN_JUMPTARGET(exit)@GOTOFF
 #else
-.L3:
+.Lsetcontext:
        .long   __setcontext
-.L4:
+.Lexit:
        .long   HIDDEN_JUMPTARGET(exit)
 #endif
        cfi_startproc