MIPS: Add new HSeqStringGetChar instruction.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 5d09a302aece1186d3808a785768633a1ff30420..2d8939f8dae3ec3b2c9f57e3361ee18dbd4299e5 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1756,6 +1756,34 @@ MemOperand LCodeGen::BuildSeqStringOperand(Register string,
 }
 
 
+void LCodeGen::DoSeqStringGetChar(LSeqStringGetChar* instr) {
+  String::Encoding encoding = instr->hydrogen()->encoding();
+  Register string = ToRegister(instr->string());
+  Register result = ToRegister(instr->result());
+
+  if (FLAG_debug_code) {
+    Register scratch = scratch0();
+    __ lw(scratch, FieldMemOperand(string, HeapObject::kMapOffset));
+    __ lbu(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+
+    __ And(scratch, scratch,
+           Operand(kStringRepresentationMask | kStringEncodingMask));
+    static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
+    static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
+    __ Subu(at, scratch, Operand(encoding == String::ONE_BYTE_ENCODING
+                                ? one_byte_seq_type : two_byte_seq_type));
+    __ Check(eq, kUnexpectedStringType, at, Operand(zero_reg));
+  }
+
+  MemOperand operand = BuildSeqStringOperand(string, instr->index(), encoding);
+  if (encoding == String::ONE_BYTE_ENCODING) {
+    __ lbu(result, operand);
+  } else {
+    __ lhu(result, operand);
+  }
+}
+
+
 void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
   String::Encoding encoding = instr->hydrogen()->encoding();
   Register string = ToRegister(instr->string());