Fix a bug in Div when all uses are truncating

Refine the related test cases to cover truncating cases

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/22964004

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16249 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-codegen-arm.cc

@@ -1398,6 +1398,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
         __ rsb(dividend, dividend, Operand(0), LeaveCC, lt);
         __ mov(dividend, Operand(dividend, ASR, power));
         if (divisor > 0) __ rsb(dividend, dividend, Operand(0), LeaveCC, lt);
+        if (divisor < 0) __ rsb(dividend, dividend, Operand(0), LeaveCC, gt);
         return;  // Don't fall through to "__ rsb" below.
       } else {
         // Deoptimize if remainder is not 0.

src/ia32/lithium-codegen-ia32.cc

@@ -1462,6 +1462,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
         __ cmp(dividend, 0);
         __ j(less, &negative, Label::kNear);
         __ sar(dividend, power);
+        if (divisor < 0) __ neg(dividend);
         __ jmp(&done, Label::kNear);
 
         __ bind(&negative);

src/x64/lithium-codegen-x64.cc

@@ -1216,6 +1216,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
         __ cmpl(dividend, Immediate(0));
         __ j(less, &negative, Label::kNear);
         __ sarl(dividend, Immediate(power));
+        if (divisor < 0) __ negl(dividend);
         __ jmp(&done, Label::kNear);
 
         __ bind(&negative);

test/mjsunit/shift-for-integer-div.js

@@ -25,35 +25,63 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Flags: --allow-natives-syntax
+
 function divp4(x) {
   return x / 4;
 }
 
-for (var i = 0; i < 10000; i+=4) {
-  assertEquals(i >> 2, divp4(i));
-}
-
+divp4(8);
+divp4(8);
+%OptimizeFunctionOnNextCall(divp4);
+assertEquals(2, divp4(8));
 assertEquals(0.5, divp4(2));
 
+
 function divn4(x) {
   return x / (-4);
 }
 
-for (var i = 0; i < 10000; i+=4) {
-  assertEquals(-(i >> 2), divn4(i));
-}
-
+divn4(8);
+divn4(8);
+%OptimizeFunctionOnNextCall(divn4);
+assertEquals(-2, divn4(8));
+// Check for (0 / -x)
 assertEquals(-0, divn4(0));
 
 
+// Check for (kMinInt / -1)
 function divn1(x) {
   return x / (-1);
 }
 
-for (var i = 0; i < 10000; i++) {
-  assertEquals(-i, divn1(i));
+var two_31 = 1 << 31;
+divn1(2);
+divn1(2);
+%OptimizeFunctionOnNextCall(divn1);
+assertEquals(-2, divn1(2));
+assertEquals(two_31, divn1(-two_31));
+
+
+//Check for truncating to int32 case
+function divp4t(x) {
+  return (x / 4) | 0;
 }
 
-var min_int = -(0x7FFFFFFF)-1;
-assertEquals(-min_int, divn1(min_int));
+divp4t(8);
+divp4t(8);
+%OptimizeFunctionOnNextCall(divp4t);
+assertEquals(-1, divp4t(-5));
+assertEquals(1, divp4t(5));
+assertOptimized(divp4t);
+
+function divn4t(x) {
+  return (x / -4) | 0;
+}
 
+divn4t(8);
+divn4t(8);
+%OptimizeFunctionOnNextCall(divn4t);
+assertEquals(1, divn4t(-5));
+assertEquals(-1, divn4t(5));
+assertOptimized(divn4t);