Change the INLINEASM_BR MachineInstr to be a non-terminating instruction.

Before this instruction supported output values, it fit fairly
naturally as a terminator. However, being a terminator while also
supporting outputs causes some trouble, as the physreg->vreg COPY
operations cannot be in the same block.

Modeling it as a non-terminator allows it to be handled the same way
as invoke is handled already.

Most of the changes here were created by auditing all the existing
users of MachineBasicBlock::isEHPad() and
MachineBasicBlock::hasEHPadSuccessor(), and adding calls to
isInlineAsmBrIndirectTarget or mayHaveInlineAsmBr, as appropriate.

Reviewed By: nickdesaulniers, void

Differential Revision: https://reviews.llvm.org/D79794

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
index 415e38d5..1d253a6 100644
--- a/llvm/lib/CodeGen/MachineSink.cpp
+++ b/llvm/lib/CodeGen/MachineSink.cpp
@@ -734,6 +734,13 @@ MachineSinking::FindSuccToSinkTo(MachineInstr &MI, MachineBasicBlock *MBB,
   if (SuccToSinkTo && SuccToSinkTo->isEHPad())
     return nullptr;
 
+  // It ought to be okay to sink instructions into an INLINEASM_BR target, but
+  // only if we make sure that MI occurs _before_ an INLINEASM_BR instruction in
+  // the source block (which this code does not yet do). So for now, forbid
+  // doing so.
+  if (SuccToSinkTo && SuccToSinkTo->isInlineAsmBrIndirectTarget())
+    return nullptr;
+
   return SuccToSinkTo;
 }