bn: Switch $i to be unused r9

No need to save/restore because it is volatile.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15798)

diff --git a/crypto/bn/asm/ppc64-mont-fixed.pl b/crypto/bn/asm/ppc64-mont-fixed.pl
index 941882ec82fc5471699f93e8d9acaca34cdea92c..bb4290182dbb48e593747a1c287bb91236fb434b 100755 (executable)
--- a/crypto/bn/asm/ppc64-mont-fixed.pl
+++ b/crypto/bn/asm/ppc64-mont-fixed.pl
@@ -72,6 +72,7 @@ my $np        = "r6";
 my $n0 = "r7";
 my $num        = "r8";
 
+my $i  = "r9";
 my $c0 = "r10";
 my $bp0        = "r11";
 my $bpi        = "r11";
@@ -81,7 +82,6 @@ my $apj       = "r12";
 my $npj        = "r12";
 my $lo = "r14";
 my $c1 = "r14";
-my $i  = "r15";
 
 # Non-volatile registers used for tp[i]
 #
@@ -346,12 +346,11 @@ sub save_registers($)
 
        $self->add_code(<<___);
        mtvsrd  $vsrs[0],$lo
-       mtvsrd  $vsrs[1],$i
 ___
 
        for (my $j = 0; $j <= $n+1; $j++) {
                $self->{code}.=<<___;
-       mtvsrd  $vsrs[$j+2],$tp[$j]
+       mtvsrd  $vsrs[$j+1],$tp[$j]
 ___
        }
 
@@ -368,12 +367,11 @@ sub restore_registers($)
 
        $self->add_code(<<___);
        mfvsrd  $lo,$vsrs[0]
-       mfvsrd  $i,$vsrs[1]
 ___
 
        for (my $j = 0; $j <= $n+1; $j++) {
                $self->{code}.=<<___;
-       mfvsrd  $tp[$j],$vsrs[$j+2]
+       mfvsrd  $tp[$j],$vsrs[$j+1]
 ___
        }