commit 80e107ccd088a2705d0e776799a8815a58061cb3
author Zequan Wu <zequanwu@google.com> Fri May 29 12:15:07 2020 -0700
committer Zequan Wu <zequanwu@google.com> Fri May 29 12:31:06 2020 -0700
tree f697f4807d0544468fbc8a9f219758837ad71d24
parent 6f56a586c505bd587106a9b94388d70efb88155b

Add NoMerge MIFlag to avoid MIR branch folding

Let the codegen recognized the nomerge attribute and disable branch folding when the attribute is given

Differential Revision: https://reviews.llvm.org/D79537

llvm/lib/CodeGen/BranchFolding.cpp

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 852bfb3..df79019 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -348,6 +348,9 @@
         MBBI1->isInlineAsm()) {
       break;
     }
+    if (MBBI1->getFlag(MachineInstr::NoMerge) ||
+        MBBI2->getFlag(MachineInstr::NoMerge))
+      break;
     ++TailLen;
     I1 = MBBI1;
     I2 = MBBI2;