[ARM] Fix llvm-objdump disassembly of armv7m object files.

Apparently, the features were getting mixed up, so we'd try to
disassemble in ARM mode. Fix sub-architecture detection to compute the
correct triple if we're detecting it automatically, so the user doesn't
need to pass --triple=thumb etc.

It's possible we should be somehow tying the "+thumb-mode" target
feature more directly to Tag_CPU_arch_profile? But this seems to work
reasonably well, anyway.

While I'm here, fix up the other llvm-objdump tests that were explicitly
specifying an ARM triple; that shouldn't be necessary.

Differential Revision: https://reviews.llvm.org/D106912

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Object/ELFObjectFile.cpp b/llvm/lib/Object/ELFObjectFile.cpp
index 6613d79..9efb28c 100644
--- a/llvm/lib/Object/ELFObjectFile.cpp
+++ b/llvm/lib/Object/ELFObjectFile.cpp
@@ -538,9 +538,16 @@ void ELFObjectFileBase::setARMSubArch(Triple &TheTriple) const {
     case ARMBuildAttrs::v6K:
       Triple += "v6k";
       break;
-    case ARMBuildAttrs::v7:
-      Triple += "v7";
+    case ARMBuildAttrs::v7: {
+      Optional<unsigned> ArchProfileAttr =
+          Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch_profile);
+      if (ArchProfileAttr.hasValue() &&
+          ArchProfileAttr.getValue() == ARMBuildAttrs::MicroControllerProfile)
+        Triple += "v7m";
+      else
+        Triple += "v7";
       break;
+    }
     case ARMBuildAttrs::v6_M:
       Triple += "v6m";
       break;