MIPS: Fix Sltu macro instruction.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index a6b818a67ac08796eba5972bae3382f73774f46e..b758a7da93a72a69354a0b08a4a32665af3e8828 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -1121,11 +1121,16 @@ void MacroAssembler::Slt(Register rd, Register rs, const Operand& rt) {
 
 
 void MacroAssembler::Sltu(Register rd, Register rs, const Operand& rt) {
+  const uint32_t int16_min = std::numeric_limits<int16_t>::min();

[balazs.kilvady, 2016/09/30 17:45:19]

This should be in the else branch.

[akos.palfi.imgtec, 2016/09/30 17:55:10]

Acknowledged.

   if (rt.is_reg()) {
     sltu(rd, rs, rt.rm());
   } else {
-    if (is_uint16(rt.imm32_) && !MustUseReg(rt.rmode_)) {
+    if (is_uint15(rt.imm32_) && !MustUseReg(rt.rmode_)) {
+      // Imm range is: [0, 32767].
       sltiu(rd, rs, rt.imm32_);
+    } else if (is_uint15(rt.imm32_ - int16_min) && !MustUseReg(rt.rmode_)) {
+      // Imm range is: [max_unsigned-32767,max_unsigned].
+      sltiu(rd, rs, static_cast<uint16_t>(rt.imm32_));

[balazs.kilvady, 2016/09/30 17:45:19]

sltiu() expects int16 or uint16? Is this cast ok?

[akos.palfi.imgtec, 2016/09/30 17:55:10]

It expects int32. This casts [ffff8000, ffffffff] to [8000, ffff], I've checked
it with the debugger.

     } else {
       // li handles the relocation.
       DCHECK(!rs.is(at));