[Linker] Remove warning when linking ARM and Thumb IR modules.

Summary:
This patch updates Triple::isCompatibleWith to make armxx and thumbxx
triples compatible, as long as the subarch, vendor, os, envorionment and
object format match. Thumb/ARM code generation should be controlled
using the thumb-mode per-function target feature rather than by the
triple to allow mixing Thumb and ARM functions.

D33448 updates Clang's codegen to add thumb-mode for all functions with
armxx or thumbxx triples.

Reviewers: echristo, t.p.northover, rafael, kristof.beyls, rengolin, tejohnson

Reviewed By: tejohnson

Subscribers: rinon, eugenis, pcc, srhines, aemerson, mehdi_amini, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33287

llvm-svn: 304884

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Support/Triple.cpp b/llvm/lib/Support/Triple.cpp
index 4e437d799cd..320aede79fb 100644
--- a/llvm/lib/Support/Triple.cpp
+++ b/llvm/lib/Support/Triple.cpp
@@ -1488,6 +1488,21 @@ bool Triple::isLittleEndian() const {
 }
 
 bool Triple::isCompatibleWith(const Triple &Other) const {
+  // ARM and Thumb triples are compatible, if subarch, vendor and OS match.
+  if ((getArch() == Triple::thumb && Other.getArch() == Triple::arm) ||
+      (getArch() == Triple::arm && Other.getArch() == Triple::thumb) ||
+      (getArch() == Triple::thumbeb && Other.getArch() == Triple::armeb) ||
+      (getArch() == Triple::armeb && Other.getArch() == Triple::thumbeb)) {
+    if (getVendor() == Triple::Apple)
+      return getSubArch() == Other.getSubArch() &&
+             getVendor() == Other.getVendor() && getOS() == Other.getOS();
+    else
+      return getSubArch() == Other.getSubArch() &&
+             getVendor() == Other.getVendor() && getOS() == Other.getOS() &&
+             getEnvironment() == Other.getEnvironment() &&
+             getObjectFormat() == Other.getObjectFormat();
+  }
+
   // If vendor is apple, ignore the version number.
   if (getVendor() == Triple::Apple)
     return getArch() == Other.getArch() && getSubArch() == Other.getSubArch() &&