[MC] Don't use the architecture to govern which object file format to use

InitMCObjectFileInfo was trying to override the triple in awkward ways.
For example, a triple specifying COFF but not Windows was forced as ELF.
This makes it easy for internal invariants to get violated, such as
those which triggered PR25912.

This fixes PR25912.

llvm-svn: 256226

1 files changed, 37 insertions, 11 deletions

diff --git a/llvm/lib/Support/Triple.cpp b/llvm/lib/Support/Triple.cpp
index 9061d17..3bb1116 100644
--- a/llvm/lib/Support/Triple.cpp
+++ b/llvm/lib/Support/Triple.cpp
@@ -538,22 +538,53 @@ static const char *getObjectFormatTypeName(Triple::ObjectFormatType Kind) {
 
 static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
   switch (T.getArch()) {
-  default:
-    break;
+  case Triple::UnknownArch:
+  case Triple::aarch64:
+  case Triple::arm:
+  case Triple::thumb:
+  case Triple::x86:
+  case Triple::x86_64:
+    if (T.isOSDarwin())
+      return Triple::MachO;
+    else if (T.isOSWindows())
+      return Triple::COFF;
+    return Triple::ELF;
+
+  case Triple::aarch64_be:
+  case Triple::amdgcn:
+  case Triple::amdil:
+  case Triple::amdil64:
+  case Triple::armeb:
+  case Triple::avr:
+  case Triple::bpfeb:
+  case Triple::bpfel:
   case Triple::hexagon:
+  case Triple::hsail:
+  case Triple::hsail64:
+  case Triple::kalimba:
+  case Triple::le32:
+  case Triple::le64:
   case Triple::mips:
-  case Triple::mipsel:
   case Triple::mips64:
   case Triple::mips64el:
+  case Triple::mipsel:
+  case Triple::msp430:
+  case Triple::nvptx:
+  case Triple::nvptx64:
+  case Triple::ppc64le:
   case Triple::r600:
-  case Triple::amdgcn:
+  case Triple::shave:
   case Triple::sparc:
+  case Triple::sparcel:
   case Triple::sparcv9:
+  case Triple::spir:
+  case Triple::spir64:
   case Triple::systemz:
+  case Triple::tce:
+  case Triple::thumbeb:
   case Triple::wasm32:
   case Triple::wasm64:
   case Triple::xcore:
-  case Triple::ppc64le:
     return Triple::ELF;
 
   case Triple::ppc:
@@ -562,12 +593,7 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
       return Triple::MachO;
     return Triple::ELF;
   }
-
-  if (T.isOSDarwin())
-    return Triple::MachO;
-  else if (T.isOSWindows())
-    return Triple::COFF;
-  return Triple::ELF;
+  llvm_unreachable("unknown architecture");
 }
 
 /// \brief Construct a triple from the string representation provided.