MIPS: Don't allow large immediates for certain instructions.

Some instructions can use >16 bit immediates if they represent a <=16 bit signed value.
However some logical instructions (andi, xori, ori, lui) should always treat the immediate value as unsigned.
This patch adds an ASSERT to these places and a minor change to MacroAssembler::li to satisfy this.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9309077
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10644 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/assembler-mips.cc

@@ -1245,6 +1245,7 @@ void Assembler::and_(Register rd, Register rs, Register rt) {
 
 
 void Assembler::andi(Register rt, Register rs, int32_t j) {
+  ASSERT(is_uint16(j));
   GenInstrImmediate(ANDI, rs, rt, j);
 }
 
@@ -1255,6 +1256,7 @@ void Assembler::or_(Register rd, Register rs, Register rt) {
 
 
 void Assembler::ori(Register rt, Register rs, int32_t j) {
+  ASSERT(is_uint16(j));
   GenInstrImmediate(ORI, rs, rt, j);
 }
 
@@ -1265,6 +1267,7 @@ void Assembler::xor_(Register rd, Register rs, Register rt) {
 
 
 void Assembler::xori(Register rt, Register rs, int32_t j) {
+  ASSERT(is_uint16(j));
   GenInstrImmediate(XORI, rs, rt, j);
 }
 
@@ -1445,6 +1448,7 @@ void Assembler::swr(Register rd, const MemOperand& rs) {
 
 
 void Assembler::lui(Register rd, int32_t j) {
+  ASSERT(is_uint16(j));
   GenInstrImmediate(LUI, zero_reg, rd, j);
 }
 

src/mips/macro-assembler-mips.cc

@@ -771,18 +771,18 @@ void MacroAssembler::li(Register rd, Operand j, bool gen2instr) {
     } else if (!(j.imm32_ & kHiMask)) {
       ori(rd, zero_reg, j.imm32_);
     } else if (!(j.imm32_ & kImm16Mask)) {
-      lui(rd, (j.imm32_ & kHiMask) >> kLuiShift);
+      lui(rd, (j.imm32_ >> kLuiShift) & kImm16Mask);
     } else {
-      lui(rd, (j.imm32_ & kHiMask) >> kLuiShift);
+      lui(rd, (j.imm32_ >> kLuiShift) & kImm16Mask);
       ori(rd, rd, (j.imm32_ & kImm16Mask));
     }
   } else if (MustUseReg(j.rmode_) || gen2instr) {
     if (MustUseReg(j.rmode_)) {
       RecordRelocInfo(j.rmode_, j.imm32_);
     }
-    // We need always the same number of instructions as we may need to patch
+    // We always need the same number of instructions as we may need to patch
     // this code to load another value which may need 2 instructions to load.
-    lui(rd, (j.imm32_ & kHiMask) >> kLuiShift);
+    lui(rd, (j.imm32_ >> kLuiShift) & kImm16Mask);
     ori(rd, rd, (j.imm32_ & kImm16Mask));
   }
 }