[mips] Set pointer size to 4 bytes for N32 ABI

[atanasyan]

Summary

CodePointerSize and CalleeSaveStackSlotSize values are used in DWARF generation. In case of MIPS it's icorrect to check for Triple::isMIPS64() only this function returns true for N32 ABI too.

Now we do not have a method to recognize N32 if it's specified by a comand line option and is not a part of a target triple. So we check for Triple::GNUABIN32 only. It's better than nothing.

[smaksimovic]

LGTM

llvm/trunk/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp

 
 using namespace llvm;
 
 void MipsMCAsmInfo::anchor() { }
 
 MipsMCAsmInfo::MipsMCAsmInfo(const Triple &TheTriple) {
   IsLittleEndian = TheTriple.isLittleEndian();
 
-  if (TheTriple.isMIPS64()) {
+  if (TheTriple.isMIPS64() && TheTriple.getEnvironment() != Triple::GNUABIN32)
     CodePointerSize = CalleeSaveStackSlotSize = 8;
-  }
 
   // FIXME: This condition isn't quite right but it's the best we can do until
   //        this object can identify the ABI. It will misbehave when using O32
   //        on a mips64*-* triple.
   if (TheTriple.isMIPS32()) {
     PrivateGlobalPrefix = "$";
     PrivateLabelPrefix = "$";
   }

llvm/trunk/test/MC/Mips/ptr-size.s

+# RUN: llvm-mc -filetype=obj -triple mips--gnu -g %s \
+# RUN:   | llvm-dwarfdump -debug-info - | FileCheck --check-prefix=O32 %s
+# RUN: llvm-mc -filetype=obj -triple mips64--gnuabin32 -g %s \
+# RUN:   | llvm-dwarfdump -debug-info - | FileCheck --check-prefix=N32 %s
+# RUN: llvm-mc -filetype=obj -triple mips64--gnuabi64 -g %s \
+# RUN:   | llvm-dwarfdump -debug-info - | FileCheck --check-prefix=N64 %s
+
+# O32: addr_size = 0x04
+# N32: addr_size = 0x04
+# N64: addr_size = 0x08
+
+foo:
+  nop