[x86] Do not relax PUSHi16 to PUSHi32 (PR18414)

They do *different* things to %esp, so they are not equivalent.

Rename PUSHi8 to PUSH32i8 and add the missing PUSH16i8.

llvm-svn: 198761
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
index 2cf6381..dfd8a65 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -217,9 +217,9 @@
   case X86::CMP64mi8: return X86::CMP64mi32;
 
     // PUSH
-  case X86::PUSHi8: return X86::PUSHi32;
-  case X86::PUSHi16: return X86::PUSHi32;
-  case X86::PUSH64i8: return X86::PUSH64i32;
+  case X86::PUSH32i8:  return X86::PUSHi32;
+  case X86::PUSH16i8:  return X86::PUSHi16;
+  case X86::PUSH64i8:  return X86::PUSH64i32;
   case X86::PUSH64i16: return X86::PUSH64i32;
   }
 }