crypto/bn/asm/x86_64-mont.pl: minor optimization.

(cherry picked from commit 72a158703bf2b33f4eba6920302941560f7a848d)

diff --git a/crypto/bn/asm/x86_64-mont.pl b/crypto/bn/asm/x86_64-mont.pl
index 78221bae3339277c32ec611fa909ed829e8ffe26..ba938d6ccdddfb9f6fe384ac3197a28830a6b3e6 100755 (executable)
--- a/crypto/bn/asm/x86_64-mont.pl
+++ b/crypto/bn/asm/x86_64-mont.pl
@@ -1378,7 +1378,6 @@ $code.=<<___;
        lea     8*8($nptr),$nptr
        xor     %rax,%rax
        mov     8(%rsp),%rdx            # pull end of t[]
-       xor     $carry,$carry
        cmp     0(%rsp),$nptr           # end of n[]?
        jae     .L8x_no_tail
 
@@ -1491,17 +1490,10 @@ $code.=<<___;
 .align 32
 .L8x_tail_done:
        add     (%rdx),%r8              # can this overflow?
-       adc     \$0,%r9
-       adc     \$0,%r10
-       adc     \$0,%r11
-       adc     \$0,%r12
-       adc     \$0,%r13
-       adc     \$0,%r14
-       adc     \$0,%r15
-       sbb     %rax,%rax
+       xor     %rax,%rax
 
-.L8x_no_tail:
        neg     $carry
+.L8x_no_tail:
        adc     8*0($tptr),%r8
        adc     8*1($tptr),%r9
        adc     8*2($tptr),%r10
@@ -1510,9 +1502,7 @@ $code.=<<___;
        adc     8*5($tptr),%r13
        adc     8*6($tptr),%r14
        adc     8*7($tptr),%r15
-       sbb     $carry,$carry
-       neg     %rax
-       sub     $carry,%rax             # top-most carry
+       adc     \$0,%rax                # top-most carry
 
        mov     40(%rsp),$nptr          # restore $nptr