Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 191 insertions, 0 deletions

diff --git a/arch/alpha/lib/ev6-memchr.S b/arch/alpha/lib/ev6-memchr.S
new file mode 100644
index 000000000000..a8e843dbcc23
--- /dev/null
+++ b/arch/alpha/lib/ev6-memchr.S
@@ -0,0 +1,191 @@
+/*
+ * arch/alpha/lib/ev6-memchr.S
+ *
+ * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Finds characters in a memory area.  Optimized for the Alpha:
+ *
+ *    - memory accessed as aligned quadwords only
+ *    - uses cmpbge to compare 8 bytes in parallel
+ *    - does binary search to find 0 byte in last
+ *      quadword (HAKMEM needed 12 instructions to
+ *      do this instead of the 9 instructions that
+ *      binary search needs).
+ *
+ * For correctness consider that:
+ *
+ *    - only minimum number of quadwords may be accessed
+ *    - the third argument is an unsigned long
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ *      Compiler Writer's Guide for the Alpha 21264
+ *      abbreviated as 'CWG' in other comments here
+ *      ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ *      E       - either cluster
+ *      U       - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ *      L       - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ * Try not to change the actual algorithm if possible for consistency.
+ */
+
+        .set noreorder
+        .set noat
+
+        .align  4
+        .globl memchr
+        .ent memchr
+memchr:
+        .frame $30,0,$26,0
+        .prologue 0
+
+        # Hack -- if someone passes in (size_t)-1, hoping to just
+        # search til the end of the address space, we will overflow
+        # below when we find the address of the last byte.  Given
+        # that we will never have a 56-bit address space, cropping
+        # the length is the easiest way to avoid trouble.
+        zap     $18, 0x80, $5   # U : Bound length
+        beq     $18, $not_found # U :
+        ldq_u   $1, 0($16)      # L : load first quadword Latency=3
+        and     $17, 0xff, $17  # E : L L U U : 00000000000000ch
+
+        insbl   $17, 1, $2      # U : 000000000000ch00
+        cmpult  $18, 9, $4      # E : small (< 1 quad) string?
+        or      $2, $17, $17    # E : 000000000000chch
+        lda     $3, -1($31)     # E : U L L U
+
+        sll     $17, 16, $2     # U : 00000000chch0000
+        addq    $16, $5, $5     # E : Max search address
+        or      $2, $17, $17    # E : 00000000chchchch
+        sll     $17, 32, $2     # U : U L L U : chchchch00000000
+
+        or      $2, $17, $17    # E : chchchchchchchch
+        extql   $1, $16, $7     # U : $7 is upper bits
+        beq     $4, $first_quad # U :
+        ldq_u   $6, -1($5)      # L : L U U L : eight or less bytes to search Latency=3
+
+        extqh   $6, $16, $6     # U : 2 cycle stall for $6
+        mov     $16, $0         # E :
+        nop                     # E :
+        or      $7, $6, $1      # E : L U L U $1 = quadword starting at $16
+
+        # Deal with the case where at most 8 bytes remain to be searched
+        # in $1.  E.g.:
+        #       $18 = 6
+        #       $1 = ????c6c5c4c3c2c1
+$last_quad:
+        negq    $18, $6         # E :
+        xor     $17, $1, $1     # E :
+        srl     $3, $6, $6      # U : $6 = mask of $18 bits set
+        cmpbge  $31, $1, $2     # E : L U L U
+
+        nop
+        nop
+        and     $2, $6, $2      # E :
+        beq     $2, $not_found  # U : U L U L
+
+$found_it:
+#if defined(__alpha_fix__) && defined(__alpha_cix__)
+        /*
+         * Since we are guaranteed to have set one of the bits, we don't
+         * have to worry about coming back with a 0x40 out of cttz...
+         */
+        cttz    $2, $3          # U0 :
+        addq    $0, $3, $0      # E : All done
+        nop                     # E :
+        ret                     # L0 : L U L U
+#else
+        /*
+         * Slow and clunky.  It can probably be improved.
+         * An exercise left for others.
+         */
+        negq    $2, $3          # E :
+        and     $2, $3, $2      # E :
+        and     $2, 0x0f, $1    # E :
+        addq    $0, 4, $3       # E :
+
+        cmoveq  $1, $3, $0      # E : Latency 2, extra map cycle
+        nop                     # E : keep with cmov
+        and     $2, 0x33, $1    # E :
+        addq    $0, 2, $3       # E : U L U L : 2 cycle stall on $0
+
+        cmoveq  $1, $3, $0      # E : Latency 2, extra map cycle
+        nop                     # E : keep with cmov
+        and     $2, 0x55, $1    # E :
+        addq    $0, 1, $3       # E : U L U L : 2 cycle stall on $0
+
+        cmoveq  $1, $3, $0      # E : Latency 2, extra map cycle
+        nop
+        nop
+        ret                     # L0 : L U L U
+#endif
+
+        # Deal with the case where $18 > 8 bytes remain to be
+        # searched.  $16 may not be aligned.
+        .align 4
+$first_quad:
+        andnot  $16, 0x7, $0    # E :
+        insqh   $3, $16, $2     # U : $2 = 0000ffffffffffff ($16<0:2> ff)
+        xor     $1, $17, $1     # E :
+        or      $1, $2, $1      # E : U L U L $1 = ====ffffffffffff
+
+        cmpbge  $31, $1, $2     # E :
+        bne     $2, $found_it   # U :
+        # At least one byte left to process.
+        ldq     $1, 8($0)       # L :
+        subq    $5, 1, $18      # E : U L U L
+
+        addq    $0, 8, $0       # E :
+        # Make $18 point to last quad to be accessed (the
+        # last quad may or may not be partial).
+        andnot  $18, 0x7, $18   # E :
+        cmpult  $0, $18, $2     # E :
+        beq     $2, $final      # U : U L U L
+
+        # At least two quads remain to be accessed.
+
+        subq    $18, $0, $4     # E : $4 <- nr quads to be processed
+        and     $4, 8, $4       # E : odd number of quads?
+        bne     $4, $odd_quad_count # U :
+        # At least three quads remain to be accessed
+        mov     $1, $4          # E : L U L U : move prefetched value to correct reg
+
+        .align  4
+$unrolled_loop:
+        ldq     $1, 8($0)       # L : prefetch $1
+        xor     $17, $4, $2     # E :
+        cmpbge  $31, $2, $2     # E :
+        bne     $2, $found_it   # U : U L U L
+
+        addq    $0, 8, $0       # E :
+        nop                     # E :
+        nop                     # E :
+        nop                     # E :
+
+$odd_quad_count:
+        xor     $17, $1, $2     # E :
+        ldq     $4, 8($0)       # L : prefetch $4
+        cmpbge  $31, $2, $2     # E :
+        addq    $0, 8, $6       # E :
+
+        bne     $2, $found_it   # U :
+        cmpult  $6, $18, $6     # E :
+        addq    $0, 8, $0       # E :
+        nop                     # E :
+
+        bne     $6, $unrolled_loop # U :
+        mov     $4, $1          # E : move prefetched value into $1
+        nop                     # E :
+        nop                     # E :
+
+$final: subq    $5, $0, $18     # E : $18 <- number of bytes left to do
+        nop                     # E :
+        nop                     # E :
+        bne     $18, $last_quad # U :
+
+$not_found:
+        mov     $31, $0         # E :
+        nop                     # E :
+        nop                     # E :
+        ret                     # L0 :
+
+        .end memchr