1 files changed, 18 insertions, 2 deletions
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index 304edc2..e102aae 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -5201,13 +5201,29 @@ std::string llvm::UpgradeDataLayoutString(StringRef DL, StringRef TT) {
   // If the datalayout matches the expected format, add pointer size address
   // spaces to the datalayout.
   std::string AddrSpaces = "-p270:32:32-p271:32:32-p272:64:64";
-  if (!DL.contains(AddrSpaces)) {
+  if (StringRef Ref = Res; !Ref.contains(AddrSpaces)) {
     SmallVector<StringRef, 4> Groups;
     Regex R("(e-m:[a-z](-p:32:32)?)(-[if]64:.*$)");
-    if (R.match(DL, &Groups))
+    if (R.match(Res, &Groups))
       Res = (Groups[1] + AddrSpaces + Groups[3]).str();
   }
 
+  // i128 values need to be 16-byte-aligned. LLVM already called into libgcc
+  // for i128 operations prior to this being reflected in the data layout, and
+  // clang mostly produced LLVM IR that already aligned i128 to 16 byte
+  // boundaries, so although this is a breaking change, the upgrade is expected
+  // to fix more IR than it breaks.
+  // Intel MCU is an exception and uses 4-byte-alignment.
+  if (!T.isOSIAMCU()) {
+    std::string I128 = "-i128:128";
+    if (StringRef Ref = Res; !Ref.contains(I128)) {
+      SmallVector<StringRef, 4> Groups;
+      Regex R("^(e(-[mpi][^-]*)*)((-[^mpi][^-]*)*)$");
+      if (R.match(Res, &Groups))
+        Res = (Groups[1] + I128 + Groups[3]).str();
+    }
+  }
+
   // For 32-bit MSVC targets, raise the alignment of f80 values to 16 bytes.
   // Raising the alignment is safe because Clang did not produce f80 values in
   // the MSVC environment before this upgrade was added.