1 files changed, 24 insertions, 25 deletions

diff --git a/erts/emulator/beam/arith_instrs.tab b/erts/emulator/beam/arith_instrs.tab
index 224945287b..67cd7c6a2a 100644
--- a/erts/emulator/beam/arith_instrs.tab
+++ b/erts/emulator/beam/arith_instrs.tab
@@ -226,9 +226,6 @@ i_bsr := shift.setup_bsr.execute;
 shift.head() {
     Eterm Op1, Op2;
     Sint shift_left_count;
-    Sint ires;
-    Eterm* bigp;
-    Eterm tmp_big[2];
 }
 
 shift.setup_bsr(Src1, Src2) {
@@ -272,35 +269,37 @@ shift.setup_bsl(Src1, Src2) {
 }
 
 shift.execute(Fail, Live, Dst) {
+    Uint big_words_needed;
+
     if (is_small(Op1)) {
-        ires = signed_val(Op1);
-        if (shift_left_count == 0 || ires == 0) {
+        Sint int_res = signed_val(Op1);
+        if (shift_left_count == 0 || int_res == 0) {
             if (is_not_integer(Op2)) {
                 goto shift_error;
             }
-            if (ires == 0) {
+            if (int_res == 0) {
                 $Dst = Op1;
                 $NEXT0();
             }
         } else if (shift_left_count < 0)  { /* Right shift */
+            Eterm bsr_res;
             shift_left_count = -shift_left_count;
             if (shift_left_count >= SMALL_BITS-1) {
-                $Dst = (ires < 0) ? SMALL_MINUS_ONE : SMALL_ZERO;
+                bsr_res = (int_res < 0) ? SMALL_MINUS_ONE : SMALL_ZERO;
             } else {
-                $Dst = make_small(ires >> shift_left_count);
+                bsr_res = make_small(int_res >> shift_left_count);
             }
+            $Dst = bsr_res;
             $NEXT0();
         } else if (shift_left_count < SMALL_BITS-1) { /* Left shift */
-            if ((ires > 0 &&
-                 ((~(Uint)0 << ((SMALL_BITS-1)-shift_left_count)) &
-                  ires) == 0) ||
-                ((~(Uint)0 << ((SMALL_BITS-1)-shift_left_count)) &
-                 ~ires) == 0) {
-                $Dst = make_small(ires << shift_left_count);
+            if ((int_res > 0 &&
+                 ((~(Uint)0 << ((SMALL_BITS-1)-shift_left_count)) & int_res) == 0) ||
+                ((~(Uint)0 << ((SMALL_BITS-1)-shift_left_count)) & ~int_res) == 0) {
+                $Dst = make_small(int_res << shift_left_count);
                 $NEXT0();
             }
         }
-        ires = 1;               /* big_size(small_to_big(Op1)) */
+        big_words_needed = 1;   /* big_size(small_to_big(Op1)) */
         goto big_shift;
     } else if (is_big(Op1)) {
         if (shift_left_count == 0) {
@@ -310,20 +309,21 @@ shift.execute(Fail, Live, Dst) {
             $Dst = Op1;
             $NEXT0();
         }
-        ires = big_size(Op1);
+        big_words_needed = big_size(Op1);
 
     big_shift:
         if (shift_left_count > 0) {	/* Left shift. */
-            ires += (shift_left_count / D_EXP);
+            big_words_needed += (shift_left_count / D_EXP);
         } else {	/* Right shift. */
-            if (ires <= (-shift_left_count / D_EXP)) {
-                ires = 3;       /* ??? */
+            if (big_words_needed <= (-shift_left_count / D_EXP)) {
+                big_words_needed = 3;       /* ??? */
             } else {
-                ires -= (-shift_left_count / D_EXP);
+                big_words_needed -= (-shift_left_count / D_EXP);
             }
         }
         {
-            ires = BIG_NEED_SIZE(ires+1);
+            Eterm tmp_big[2];
+            Sint big_need_size = BIG_NEED_SIZE(big_words_needed+1);
 
             /*
              * Slightly conservative check the size to avoid
@@ -331,15 +331,14 @@ shift.execute(Fail, Live, Dst) {
              * clearly would overflow the arity in the header
              * word.
              */
-            if (ires-8 > BIG_ARITY_MAX) {
+            if (big_need_size-8 > BIG_ARITY_MAX) {
                 $SYSTEM_LIMIT($Fail);
             }
-            $GC_TEST_PRESERVE(ires+1, $Live, Op1);
+            $GC_TEST_PRESERVE(big_need_size+1, $Live, Op1);
             if (is_small(Op1)) {
                 Op1 = small_to_big(signed_val(Op1), tmp_big);
             }
-            bigp = HTOP;
-            Op1 = big_lshift(Op1, shift_left_count, bigp);
+            Op1 = big_lshift(Op1, shift_left_count, HTOP);
             if (is_big(Op1)) {
                 HTOP += bignum_header_arity(*HTOP) + 1;
             }