Do not use repeated subtractions in mod-i, it hurts performance in general.

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1147 matching lines @@
     __ bind(&done);
     return;
   }
 
   // These registers hold untagged 32 bit values.
   Register left = ToRegister(instr->left());
   Register right = ToRegister(instr->right());
   Register result = ToRegister(instr->result());
   Label done;
 
+    // Check for x % 0.
+  if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
+    __ cmp(right, Operand::Zero());
+    DeoptimizeIf(eq, instr->environment());
+  }
+
   if (CpuFeatures::IsSupported(SUDIV)) {
     CpuFeatureScope scope(masm(), SUDIV);
-    // Check for x % 0.
-    if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
-      __ cmp(right, Operand::Zero());
-      DeoptimizeIf(eq, instr->environment());
-    }
-
     // Check for (kMinInt % -1).
     if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
       Label left_not_min_int;
       __ cmp(left, Operand(kMinInt));
       __ b(ne, &left_not_min_int);
       __ cmp(right, Operand(-1));
       DeoptimizeIf(eq, instr->environment());
       __ bind(&left_not_min_int);
     }
 
     // For  r3 = r1 % r2; we can have the following ARM code
     // sdiv r3, r1, r2
     // mls r3, r3, r2, r1
 
     __ sdiv(result, left, right);
     __ mls(result, result, right, left);
-    __ cmp(result, Operand::Zero());
-    __ b(ne, &done);
 
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
-       __ cmp(left, Operand::Zero());
-       DeoptimizeIf(lt, instr->environment());
+      __ cmp(result, Operand::Zero());
+      __ b(ne, &done);
+      __ cmp(left, Operand::Zero());
+      DeoptimizeIf(lt, instr->environment());
     }
   } else {
     Register scratch = scratch0();
     Register scratch2 = ToRegister(instr->temp());
     DwVfpRegister dividend = ToDoubleRegister(instr->temp2());
     DwVfpRegister divisor = ToDoubleRegister(instr->temp3());
     DwVfpRegister quotient = double_scratch0();
 
     ASSERT(!dividend.is(divisor));
     ASSERT(!dividend.is(quotient));
     ASSERT(!divisor.is(quotient));
     ASSERT(!scratch.is(left));
     ASSERT(!scratch.is(right));
     ASSERT(!scratch.is(result));
 
-    Label vfp_modulo, both_positive, right_negative;
-
-    // Check for x % 0.
-    if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
-      __ cmp(right, Operand::Zero());
-      DeoptimizeIf(eq, instr->environment());
-    }
+    Label vfp_modulo, right_negative;
 
     __ Move(result, left);
 
     // (0 % x) must yield 0 (if x is finite, which is the case here).
     __ cmp(left, Operand::Zero());
     __ b(eq, &done);
     // Preload right in a vfp register.
     __ vmov(divisor.low(), right);
     __ b(lt, &vfp_modulo);
 
     __ cmp(left, Operand(right));
     __ b(lt, &done);
 
     // Check for (positive) power of two on the right hand side.
     __ JumpIfNotPowerOfTwoOrZeroAndNeg(right,
                                        scratch,
                                        &right_negative,
-                                       &both_positive);
+                                       &vfp_modulo);
     // Perform modulo operation (scratch contains right - 1).
     __ and_(result, scratch, Operand(left));
     __ b(&done);
 
     __ bind(&right_negative);
     // Negate right. The sign of the divisor does not matter.
     __ rsb(right, right, Operand::Zero());
 
-    __ bind(&both_positive);
-    const int kUnfolds = 3;
-    // If the right hand side is smaller than the (nonnegative)
-    // left hand side, the left hand side is the result.
-    // Else try a few subtractions of the left hand side.
-    __ mov(scratch, left);
-    for (int i = 0; i < kUnfolds; i++) {
-      // Check if the left hand side is less or equal than the
-      // the right hand side.
-      __ cmp(scratch, Operand(right));
-      __ mov(result, scratch, LeaveCC, lt);
-      __ b(lt, &done);
-      // If not, reduce the left hand side by the right hand
-      // side and check again.
-      if (i < kUnfolds - 1) __ sub(scratch, scratch, right);
-    }
-
     __ bind(&vfp_modulo);
     // Load the arguments in VFP registers.
     // The divisor value is preloaded before. Be careful that 'right'
     // is only live on entry.
     __ vmov(dividend.low(), left);
     // From here on don't use right as it may have been reallocated
     // (for example to scratch2).
     right = no_reg;
 
     __ vcvt_f64_s32(dividend, dividend.low());
@@ skipping 4791 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal