target-mips: Fix incorrect shift for SHILO and SHILOV

helper_shilo has not been shifting an accumulator value correctly for negative
values in 'shift' field. Minor optimization for shift=0 case.
This change also adds tests that will trigger issue and check for regressions.

Signed-off-by: Petar Jovanovic <petarj@mips.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Eric Johnson <ericj@mips.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/tcg/mips/mips32-dsp/shilov.c b/tests/tcg/mips/mips32-dsp/shilov.c
index f186032a14..e1d6cea4b6 100644
--- a/tests/tcg/mips/mips32-dsp/shilov.c
+++ b/tests/tcg/mips/mips32-dsp/shilov.c
@@ -25,5 +25,25 @@ int main()
     assert(ach == resulth);
     assert(acl == resultl);
 
+
+    rs  = 0xffffffff;
+    ach = 0x1;
+    acl = 0x80000000;
+
+    resulth = 0x3;
+    resultl = 0x0;
+
+    __asm
+        ("mthi %0, $ac1\n\t"
+         "mtlo %1, $ac1\n\t"
+         "shilov $ac1, %2\n\t"
+         "mfhi %0, $ac1\n\t"
+         "mflo %1, $ac1\n\t"
+         : "+r"(ach), "+r"(acl)
+         : "r"(rs)
+        );
+    assert(ach == resulth);
+    assert(acl == resultl);
+
     return 0;
 }