Support for SDIV and MLS ARM instructions, and implement DoModI using them

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
===================================================================
--- src/arm/lithium-codegen-arm.cc	(revision 12559)
+++ src/arm/lithium-codegen-arm.cc	(working copy)
@@ -979,7 +979,28 @@
   Register left = ToRegister(instr->left());
   Register right = ToRegister(instr->right());
   Register result = ToRegister(instr->result());
+#if CAN_USE_INTEGER_DIVISION

[danno, 2012/09/27 15:28:09]

Need to be a runtime check rather than a compile-time check, introduced in the
same way as VFP3 support works. 

+  // Check for x % 0.
+  if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
+    __ cmp(right, Operand(0));
+    DeoptimizeIf(eq, instr->environment());
+  }
 
+  Label done;
+  // 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(0));
+  __ b(ne, &done);
+
+  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
+     __ cmp(left, Operand(0));
+     DeoptimizeIf(lt, instr->environment());
+  }
+#else
   Register scratch = scratch0();
   Register scratch2 = ToRegister(instr->temp());
   DwVfpRegister dividend = ToDoubleRegister(instr->temp2());
@@ -1081,7 +1102,7 @@
     // Load the result and we are done.
     __ mov(result, scratch2);
   }
-
+#endif
   __ bind(&done);
 }