[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

llvm/lib/MC/MCObjectFileInfo.cpp

@@ -606,7 +606,6 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
   // though it contains relocatable pointers.  In PIC mode, this is probably a
   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
   // adjusted or this should be a data section.
-  assert(T.isOSWindows() && "Windows is the only supported COFF target");
   if (T.getArch() == Triple::x86_64) {
     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
     LSDASection = nullptr;
@@ -810,25 +809,26 @@ void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple,
 
   TT = TheTriple;
 
-  Triple::ArchType Arch = TT.getArch();
-  // FIXME: Checking for Arch here to filter out bogus triples such as
-  // cellspu-apple-darwin. Perhaps we should fix in Triple?
-  if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
-       Arch == Triple::arm || Arch == Triple::thumb ||
-       Arch == Triple::aarch64 ||
-       Arch == Triple::ppc || Arch == Triple::ppc64 ||
-       Arch == Triple::UnknownArch) &&
-      TT.isOSBinFormatMachO()) {
+  switch (TT.getObjectFormat()) {
+  case Triple::MachO:
     Env = IsMachO;
     initMachOMCObjectFileInfo(TT);
-  } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
-              Arch == Triple::arm || Arch == Triple::thumb) &&
-             (TT.isOSWindows() && TT.getObjectFormat() == Triple::COFF)) {
+    break;
+  case Triple::COFF:
+    if (!TT.isOSWindows())
+      report_fatal_error(
+          "Cannot initialize MC for non-Windows COFF object files.");
+
     Env = IsCOFF;
     initCOFFMCObjectFileInfo(TT);
-  } else {
+    break;
+  case Triple::ELF:
     Env = IsELF;
     initELFMCObjectFileInfo(TT);
+    break;
+  case Triple::UnknownObjectFormat:
+    report_fatal_error("Cannot initialize MC for unknown object file format.");
+    break;
   }
 }
 

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.

llvm/test/CodeGen/X86/statepoint-stackmap-format.ll

@@ -1,5 +1,5 @@
 ; RUN: llc < %s -mtriple="x86_64-pc-linux-gnu" | FileCheck %s
-; RUN: llc < %s -mtriple="x86_64-pc-win64-coff" | FileCheck %s
+; RUN: llc < %s -mtriple="x86_64-pc-unknown-elf" | FileCheck %s
 
 ; This test is a sanity check to ensure statepoints are generating StackMap
 ; sections correctly.  This is not intended to be a rigorous test of the 

llvm/test/MC/COFF/ARM/directive-type-diagnostics.s

@@ -1,10 +0,0 @@
-// RUN: not llvm-mc -triple arm-coff -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
-// RUN: not llvm-mc -triple armeb-coff -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
-// RUN: not llvm-mc -triple thumb-coff -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
-// RUN: not llvm-mc -triple thumbeb-coff -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
-
-        .type symbol 32
-// CHECK: error: expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '%<type>' or "<type>"
-// CHECK: .type symbol 32
-// CHECK:              ^
-

llvm/test/MC/ELF/ARM/directive-type-diagnostics.s

@@ -0,0 +1,10 @@
+// RUN: not llvm-mc -triple arm-elf -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
+// RUN: not llvm-mc -triple armeb-elf -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
+// RUN: not llvm-mc -triple thumb-elf -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
+// RUN: not llvm-mc -triple thumbeb-elf -filetype asm -o /dev/null %s 2>&1 | FileCheck %s
+
+        .type symbol 32
+// CHECK: error: expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '%<type>' or "<type>"
+// CHECK: .type symbol 32
+// CHECK:              ^
+