Implementing a few more missing stubs on ARM:...

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
===================================================================
--- src/arm/lithium-codegen-arm.cc	(revision 6231)
+++ src/arm/lithium-codegen-arm.cc	(working copy)
@@ -1380,15 +1380,64 @@
 }
 
 
-// Branches to a label or falls through with the answer in the z flag.  Trashes
-// the temp registers, but not the input.  Only input and temp2 may alias.
+// Branches to a label or falls through with the answer in the z flag. Trashes
+// the temp registers, but not the input. Only input and temp2 may alias.

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

input is trashed if temp2 aliases it.

[Alexandre, 2011/01/10 10:48:27]

Indeed. Changed the code to have input and temp2 always different.
I have a few questions however:
- The ia32 comment states that input is not trashed. Is it required?
- More generally, where can I find information on what each LCodeGen stub
requires? I can find some info in the lithium-<arch>.* files, but how do I know
for example if the stub is allowed to trash the input?
On 2011/01/10 09:56:08, Søren Gjesse wrote:

 void LCodeGen::EmitClassOfTest(Label* is_true,
                                Label* is_false,
                                Handle<String>class_name,
                                Register input,
                                Register temp,
                                Register temp2) {
-  Abort("EmitClassOfTest unimplemented.");
+  ASSERT(!input.is(temp));
+  ASSERT(!temp.is(temp2));  // But input and temp2 may be the same register.
+
+  __ BranchOnSmi(input, is_false);
+
+  __ CompareObjectType(input, temp, temp2, FIRST_JS_OBJECT_TYPE);
+  __ b(lt, is_false);
+

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

How about just

// temp:  map of input
// temp2: object type of input

[Alexandre, 2011/01/10 10:48:27]

Done.

+  // After CompareObjectType:
+  //   - Input's map is in temp.
+  //   - Input's type is in temp2.
+
+  // Functions have class 'Function'.
+  __ cmp(temp2, Operand(JS_FUNCTION_TYPE));
+  if (class_name->IsEqualTo(CStrVector("Function"))) {
+    __ b(eq, is_true);
+  } else {
+    __ b(eq, is_false);
+  }
+
+  // Check if the constructor in the map is a function.
+  __ ldr(temp, FieldMemOperand(temp, Map::kConstructorOffset));

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

After this

// temp: constructor

[Alexandre, 2011/01/10 10:48:27]

Done.

+
+  // As long as JS_FUNCTION_TYPE is the last instance type and it is
+  // right after LAST_JS_OBJECT_TYPE, we can avoid checking for
+  // LAST_JS_OBJECT_TYPE.
+  ASSERT(LAST_TYPE == JS_FUNCTION_TYPE);
+  ASSERT(JS_FUNCTION_TYPE == LAST_JS_OBJECT_TYPE + 1);
+
+  // Objects with a non-function constructor have class 'Object'.
+  __ CompareObjectType(temp, temp2, temp2, JS_FUNCTION_TYPE);
+  if (class_name->IsEqualTo(CStrVector("Object"))) {
+    __ b(ne, is_true);
+  } else {
+    __ b(ne, is_false);
+  }
+

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

Change comment to

// Get the instance class name from the constructor.

[Alexandre, 2011/01/10 10:48:27]

Done.

+  // temp now contains the constructor function. Grab the
+  // instance class name from there.
+  __ ldr(temp, FieldMemOperand(temp, JSFunction::kSharedFunctionInfoOffset));
+  __ ldr(temp, FieldMemOperand(temp,
+                               SharedFunctionInfo::kInstanceClassNameOffset));
+  // The class name we are testing against is a symbol because it's a literal.
+  // The name in the constructor is a symbol because of the way the context is
+  // booted.  This routine isn't expected to work for random API-created
+  // classes and it doesn't have to because you can't access it with natives
+  // syntax.  Since both sides are symbols it is sufficient to use an identity
+  // comparison.
+  __ cmp(temp, Operand(class_name));
+  // End with the answer in the z flag.
 }
 
 
@@ -1398,7 +1447,26 @@
 
 
 void LCodeGen::DoClassOfTestAndBranch(LClassOfTestAndBranch* instr) {
-  Abort("DoClassOfTestAndBranch unimplemented.");
+  Register input = ToRegister(instr->input());
+  Register temp = ToRegister(instr->temporary());
+  Register temp2 = ToRegister(instr->temporary2());
+  if (input.is(temp)) {
+    // Swap.

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

There is a Swap instruction in the macro assembler.

[Alexandre, 2011/01/10 10:48:27]

Removed. Not needed anymore, as all these registers should be different.
On 2011/01/10 09:56:08, Søren Gjesse wrote:

+    Register swapper = temp;
+    temp = temp2;
+    temp2 = swapper;
+  }
+  Handle<String> class_name = instr->hydrogen()->class_name();
+
+  int true_block = chunk_->LookupDestination(instr->true_block_id());
+  int false_block = chunk_->LookupDestination(instr->false_block_id());
+
+  Label* true_label = chunk_->GetAssemblyLabel(true_block);
+  Label* false_label = chunk_->GetAssemblyLabel(false_block);
+
+  EmitClassOfTest(true_label, false_label, class_name, input, temp, temp2);
+
+  EmitBranch(true_block, false_block, eq);
 }
 
 
@@ -1784,12 +1852,42 @@
 
 
 void LCodeGen::DoMathFloor(LUnaryMathOperation* instr) {
-  Abort("DoMathFloor unimplemented.");
+  DoubleRegister input_reg = ToDoubleRegister(instr->input());

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

input_reg -> input?

+  SwVfpRegister single_precision_scratch = s0;

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

Please add double_scratch0() and single_scratch0() (and perhaps
single_scratch1()) like scratch0().

+  Register result = ToRegister(instr->result());
+  Register scratch = scratch0();
+
+  // Set custom FPCSR:
+  //  - Set rounding mode to "Round towards Minus Infinity"

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

No need to refer to specific bit numbers in the comments.

+  //    (ie bits [23:22] = 0b10).
+  //  - Clear vfp cumulative exception flags (bits [3:0]).
+  //  - Make sure Flush-to-zero mode control bit is unset (bit 22).
+  __ vmrs(scratch);

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

Don't we need to backup and restore FPSCR here? Thats done in
CallStubCompiler::CompileMathFloorCall.

+  __ bic(scratch, scratch,
+      Operand(kVFPExceptionMask | kVFPRoundingModeMask | kVFPFlushToZeroMask));
+  __ orr(scratch, scratch, Operand(kVFPRoundToMinusInfinityBits));
+  __ vmsr(scratch);
+
+  // Convert the argument to an integer.
+  __ vcvt_s32_f64(single_precision_scratch,
+                  input_reg,
+                  Assembler::FPSCRRounding,
+                  al);
+
+  // Retrieve FPSCR and check for vfp exceptions.
+  __ vmrs(scratch);
+  __ tst(scratch, Operand(kVFPExceptionMask));
+  DeoptimizeIf(ne, instr->environment());
+
+  // Move the result back to general purpose register r0.
+  __ vmov(result, single_precision_scratch);
 }
 
 
 void LCodeGen::DoMathSqrt(LUnaryMathOperation* instr) {
-  Abort("DoMathSqrt unimplemented.");
+  DoubleRegister input_reg = ToDoubleRegister(instr->input());

[Søren Thygesen Gjesse, 2011/01/10 09:56:08]

input_reg -> input?

[Alexandre, 2011/01/10 10:48:27]

Done.

+  ASSERT(ToDoubleRegister(instr->result()).is(input_reg));
+  __ vsqrt(input_reg, input_reg);
 }