Fix many -Wsign-compare and -Wtautological-constant-compare warnings.

Most of the -Wsign-compare warnings are due to the fact that
enums are signed by default in the MS ABI, while the
tautological comparison warnings trigger on x86 builds where
sizeof(size_t) is 4 bytes, so N > numeric_limits<unsigned>::max()
is always false.

Differential Revision: https://reviews.llvm.org/D41256

llvm-svn: 320750
diff --git a/llvm/lib/Object/COFFObjectFile.cpp b/llvm/lib/Object/COFFObjectFile.cpp
index 06ac6df..b544fa5 100644
--- a/llvm/lib/Object/COFFObjectFile.cpp
+++ b/llvm/lib/Object/COFFObjectFile.cpp
@@ -895,7 +895,7 @@
   }
 }
 
-unsigned COFFObjectFile::getArch() const {
+Triple::ArchType COFFObjectFile::getArch() const {
   switch (getMachine()) {
   case COFF::IMAGE_FILE_MACHINE_I386:
     return Triple::x86;
diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index 4620fdd..83becc4 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -2573,7 +2573,7 @@
       .Default(false);
 }
 
-unsigned MachOObjectFile::getArch() const {
+Triple::ArchType MachOObjectFile::getArch() const {
   return getArch(getCPUType(*this));
 }
 
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 677fccc..4137757 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -1038,7 +1038,7 @@
 
 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
 
-unsigned WasmObjectFile::getArch() const { return Triple::wasm32; }
+Triple::ArchType WasmObjectFile::getArch() const { return Triple::wasm32; }
 
 SubtargetFeatures WasmObjectFile::getFeatures() const {
   return SubtargetFeatures();