Accelerate charCodeAt on ARM.

Review URL: http://codereview.chromium.org/402012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3327 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/codegen-arm.cc

@@ -3286,7 +3286,82 @@ void CodeGenerator::GenerateIsNonNegativeSmi(ZoneList<Expression*>* args) {
 void CodeGenerator::GenerateFastCharCodeAt(ZoneList<Expression*>* args) {
   VirtualFrame::SpilledScope spilled_scope;
   ASSERT(args->length() == 2);
+  Comment(masm_, "[ GenerateFastCharCodeAt");
+
+  LoadAndSpill(args->at(0));
+  LoadAndSpill(args->at(1));
+  frame_->EmitPop(r0);  // Index.
+  frame_->EmitPop(r1);  // String.
+
+  Label slow, end, not_a_flat_string, ascii_string, try_again_with_new_string;
+
+  __ tst(r1, Operand(kSmiTagMask));
+  __ b(eq, &slow);  // The 'string' was a Smi.
+
+  ASSERT(kSmiTag == 0);
+  __ tst(r0, Operand(kSmiTagMask | 0x80000000u));
+  __ b(ne, &slow);  // The index was negative or not a Smi.
+
+  __ bind(&try_again_with_new_string);
+  __ CompareObjectType(r1, r2, r2, FIRST_NONSTRING_TYPE);
+  __ b(ge, &slow);
+
+  // Now r2 has the string type.
+  __ ldr(r3, FieldMemOperand(r1, String::kLengthOffset));
+  __ and_(r4, r2, Operand(kStringSizeMask));
+  __ add(r4, r4, Operand(String::kLongLengthShift));
+  __ mov(r3, Operand(r3, LSR, r4));
+  // Now r3 has the length of the string.  Compare with the index.
+  __ cmp(r3, Operand(r0, LSR, kSmiTagSize));
+  __ b(le, &slow);
+
+  // Here we know the index is in range.  Check that string is sequential.
+  ASSERT_EQ(0, kSeqStringTag);
+  __ tst(r2, Operand(kStringRepresentationMask));
+  __ b(ne, &not_a_flat_string);
+
+  // Check whether it is an ASCII string.
+  ASSERT_EQ(0, kTwoByteStringTag);
+  __ tst(r2, Operand(kStringEncodingMask));
+  __ b(ne, &ascii_string);
+
+  // 2-byte string.  We can add without shifting since the Smi tag size is the
+  // log2 of the number of bytes in a two-byte character.
+  ASSERT_EQ(1, kSmiTagSize);
+  ASSERT_EQ(1, kSmiShiftSize);
+  __ add(r1, r1, Operand(r0));
+  __ ldrh(r0, FieldMemOperand(r1, SeqTwoByteString::kHeaderSize));
+  __ mov(r0, Operand(r0, LSL, kSmiTagSize));
+  __ jmp(&end);
+
+  __ bind(&ascii_string);
+  __ add(r1, r1, Operand(r0, LSR, kSmiTagSize));
+  __ ldrb(r0, FieldMemOperand(r1, SeqAsciiString::kHeaderSize));
+  __ mov(r0, Operand(r0, LSL, kSmiTagSize));
+  __ jmp(&end);
+
+  __ bind(&not_a_flat_string);
+  __ and_(r2, r2, Operand(kStringRepresentationMask));
+  __ cmp(r2, Operand(kConsStringTag));
+  __ b(ne, &slow);
+
+  // ConsString.
+  // Check that the right hand side is the empty string (ie if this is really a
+  // flat string in a cons string).  If that is not the case we would rather go
+  // to the runtime system now, to flatten the string.
+  __ ldr(r2, FieldMemOperand(r1, ConsString::kSecondOffset));
+  __ LoadRoot(r3, Heap::kEmptyStringRootIndex);
+  __ cmp(r2, Operand(r3));
+  __ b(ne, &slow);
+
+  // Get the first of the two strings.
+  __ ldr(r1, FieldMemOperand(r1, ConsString::kFirstOffset));
+  __ jmp(&try_again_with_new_string);
+
+  __ bind(&slow);
   __ LoadRoot(r0, Heap::kUndefinedValueRootIndex);
+
+  __ bind(&end);
   frame_->EmitPush(r0);
 }
 

src/x64/codegen-x64.cc

@@ -3745,10 +3745,11 @@ void CodeGenerator::GenerateFastCharCodeAt(ZoneList<Expression*>* args) {
   __ movzxbl(temp.reg(), FieldOperand(temp.reg(), Map::kInstanceTypeOffset));
 
   // We need special handling for non-flat strings.
-  ASSERT(kSeqStringTag == 0);
+  ASSERT_EQ(0, kSeqStringTag);
   __ testb(temp.reg(), Immediate(kStringRepresentationMask));
   __ j(not_zero, &not_a_flat_string);
   // Check for 1-byte or 2-byte string.
+  ASSERT_EQ(0, kTwoByteStringTag);
   __ testb(temp.reg(), Immediate(kStringEncodingMask));
   __ j(not_zero, &ascii_string);
 

test/mjsunit/string-charcodeat.js

@@ -30,7 +30,7 @@
  */
 
 function Cons() {
-  return "Te" + "st";
+  return "Te" + "st testing 123";
 }
 
 
@@ -38,22 +38,22 @@ function Deep() {
   var a = "T";
   a += "e";
   a += "s";
-  a += "t";
+  a += "ting testing 123";
   return a;
 }
 
 
 function Slice() {
-  return "testing Testing".substring(8, 12);
+  return "testing Testing testing 123456789012345".substring(8, 22);
 }
 
 
 function Flat() {
-  return "Test";
+  return "Testing testing 123";
 }
 
 function Cons16() {
-  return "Te" + "\u1234t";
+  return "Te" + "\u1234t testing 123";
 }
 
 
@@ -61,18 +61,18 @@ function Deep16() {
   var a = "T";
   a += "e";
   a += "\u1234";
-  a += "t";
+  a += "ting testing 123";
   return a;
 }
 
 
 function Slice16Beginning() {
-  return "Te\u1234t test".substring(0, 4);
+  return "Te\u1234t testing testing 123".substring(0, 14);
 }
 
 
 function Slice16Middle() {
-  return "test Te\u1234t test".substring(5, 9);
+  return "test Te\u1234t testing testing 123".substring(5, 19);
 }
 
 
@@ -82,7 +82,7 @@ function Slice16End() {
 
 
 function Flat16() {
-  return "Te\u1234t";
+  return "Te\u1234ting testing 123";
 }
 
 
@@ -108,32 +108,35 @@ function NotAString16() {
 
 function TestStringType(generator, sixteen) {
   var g = generator;
-  assertTrue(isNaN(g().charCodeAt(-1e19)));
-  assertTrue(isNaN(g().charCodeAt(-0x80000001)));
-  assertTrue(isNaN(g().charCodeAt(-0x80000000)));
-  assertTrue(isNaN(g().charCodeAt(-0x40000000)));
-  assertTrue(isNaN(g().charCodeAt(-1)));
-  assertTrue(isNaN(g().charCodeAt(4)));
-  assertTrue(isNaN(g().charCodeAt(5)));
-  assertTrue(isNaN(g().charCodeAt(0x3fffffff)));
-  assertTrue(isNaN(g().charCodeAt(0x7fffffff)));
-  assertTrue(isNaN(g().charCodeAt(0x80000000)));
-  assertTrue(isNaN(g().charCodeAt(1e9)));
-  assertEquals(84, g().charCodeAt(0));
-  assertEquals(84, g().charCodeAt("test"));
-  assertEquals(84, g().charCodeAt(""));
-  assertEquals(84, g().charCodeAt(null));
-  assertEquals(84, g().charCodeAt(undefined));
-  assertEquals(84, g().charCodeAt());
-  assertEquals(84, g().charCodeAt(void 0));
-  assertEquals(84, g().charCodeAt(false));
-  assertEquals(101, g().charCodeAt(true));
-  assertEquals(101, g().charCodeAt(1));
-  assertEquals(sixteen ? 0x1234 : 115, g().charCodeAt(2));
-  assertEquals(116, g().charCodeAt(3));
-  assertEquals(101, g().charCodeAt(1.1));
-  assertEquals(sixteen ? 0x1234 : 115, g().charCodeAt(2.1718));
-  assertEquals(116, g().charCodeAt(3.14159));
+  var len = g().toString().length;
+  var t = sixteen ? "t" : "f"
+  t += generator.name;
+  assertTrue(isNaN(g().charCodeAt(-1e19)), 1 + t);
+  assertTrue(isNaN(g().charCodeAt(-0x80000001)), 2 + t);
+  assertTrue(isNaN(g().charCodeAt(-0x80000000)), 3 + t);
+  assertTrue(isNaN(g().charCodeAt(-0x40000000)), 4 + t);
+  assertTrue(isNaN(g().charCodeAt(-1)), 5 + t);
+  assertTrue(isNaN(g().charCodeAt(len)), 6 + t);
+  assertTrue(isNaN(g().charCodeAt(len + 1)), 7 + t);
+  assertTrue(isNaN(g().charCodeAt(0x3fffffff)), 8 + t);
+  assertTrue(isNaN(g().charCodeAt(0x7fffffff)), 9 + t);
+  assertTrue(isNaN(g().charCodeAt(0x80000000)), 10 + t);
+  assertTrue(isNaN(g().charCodeAt(1e9)), 11 + t);
+  assertEquals(84, g().charCodeAt(0), 12 + t);
+  assertEquals(84, g().charCodeAt("test"), 13 + t);
+  assertEquals(84, g().charCodeAt(""), 14 + t);
+  assertEquals(84, g().charCodeAt(null), 15 + t);
+  assertEquals(84, g().charCodeAt(undefined), 16 + t);
+  assertEquals(84, g().charCodeAt(), 17 + t);
+  assertEquals(84, g().charCodeAt(void 0), 18 + t);
+  assertEquals(84, g().charCodeAt(false), 19 + t);
+  assertEquals(101, g().charCodeAt(true), 20 + t);
+  assertEquals(101, g().charCodeAt(1), 21 + t);
+  assertEquals(sixteen ? 0x1234 : 115, g().charCodeAt(2), 22 + t);
+  assertEquals(116, g().charCodeAt(3), 23 + t);
+  assertEquals(101, g().charCodeAt(1.1), 24 + t);
+  assertEquals(sixteen ? 0x1234 : 115, g().charCodeAt(2.1718), 25 + t);
+  assertEquals(116, g().charCodeAt(3.14159), 26 + t);
 }
 
 
@@ -157,10 +160,10 @@ function StupidThing() {
   this.charCodeAt = String.prototype.charCodeAt;
 }
 
-assertEquals(52, new StupidThing().charCodeAt(0));
-assertEquals(50, new StupidThing().charCodeAt(1));
-assertTrue(isNaN(new StupidThing().charCodeAt(2)));
-assertTrue(isNaN(new StupidThing().charCodeAt(-1)));
+assertEquals(52, new StupidThing().charCodeAt(0), 27);
+assertEquals(50, new StupidThing().charCodeAt(1), 28);
+assertTrue(isNaN(new StupidThing().charCodeAt(2)), 29);
+assertTrue(isNaN(new StupidThing().charCodeAt(-1)), 30);
 
 
 // Medium (>255) and long (>65535) strings.
@@ -178,12 +181,12 @@ long += long + long + long;     // 4096.
 long += long + long + long;     // 16384.
 long += long + long + long;     // 65536.
 
-assertTrue(isNaN(medium.charCodeAt(-1)));
-assertEquals(49, medium.charCodeAt(0));
-assertEquals(56, medium.charCodeAt(255));
-assertTrue(isNaN(medium.charCodeAt(256)));
+assertTrue(isNaN(medium.charCodeAt(-1)), 31);
+assertEquals(49, medium.charCodeAt(0), 32);
+assertEquals(56, medium.charCodeAt(255), 33);
+assertTrue(isNaN(medium.charCodeAt(256)), 34);
 
-assertTrue(isNaN(long.charCodeAt(-1)));
-assertEquals(49, long.charCodeAt(0));
-assertEquals(56, long.charCodeAt(65535));
-assertTrue(isNaN(long.charCodeAt(65536)));
+assertTrue(isNaN(long.charCodeAt(-1)), 35);
+assertEquals(49, long.charCodeAt(0), 36);
+assertEquals(56, long.charCodeAt(65535), 37);
+assertTrue(isNaN(long.charCodeAt(65536)), 38);