Don't generate a shift left by one if can deoptimize on ia32 and arm and mips.

BUG=
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/21196006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15958 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-codegen-arm.cc

@@ -1744,7 +1744,9 @@ void LCodeGen::DoShiftI(LShiftI* instr) {
         if (shift_count != 0) {
           if (instr->hydrogen_value()->representation().IsSmi() &&
               instr->can_deopt()) {
-            __ mov(result, Operand(left, LSL, shift_count - 1));
+            if (shift_count != 1) {
+              __ mov(result, Operand(left, LSL, shift_count - 1));
+            }
             __ SmiTag(result, result, SetCC);
             DeoptimizeIf(vs, instr->environment());
           } else {

src/ia32/lithium-codegen-ia32.cc

@@ -1771,7 +1771,9 @@ void LCodeGen::DoShiftI(LShiftI* instr) {
         if (shift_count != 0) {
           if (instr->hydrogen_value()->representation().IsSmi() &&
               instr->can_deopt()) {
-            __ shl(ToRegister(left), shift_count - 1);
+            if (shift_count != 1) {
+              __ shl(ToRegister(left), shift_count - 1);
+            }
             __ SmiTag(ToRegister(left));
             DeoptimizeIf(overflow, instr->environment());
           } else {

src/mips/lithium-codegen-mips.cc

@@ -1583,7 +1583,9 @@ void LCodeGen::DoShiftI(LShiftI* instr) {
         if (shift_count != 0) {
           if (instr->hydrogen_value()->representation().IsSmi() &&
               instr->can_deopt()) {
-            __ sll(result, left, shift_count - 1);
+            if (shift_count != 1) {
+              __ sll(result, left, shift_count - 1);
+            }
             __ SmiTagCheckOverflow(result, result, scratch);
             DeoptimizeIf(lt, instr->environment(), scratch, Operand(zero_reg));
           } else {