[MachineOutliner] Avoid outlining XRay pseudo-instructions

[duck-37]

Summary

Outlining these can cause assertion failures and runs counter to what XRay is meant for anyway (fine-grained profiling via compiler instrumentation). Unblocks https://reviews.llvm.org/D124707

[paquette]

llvm/test/CodeGen/AArch64/machine-outliner-patchable-exit.mir

5

Can you add testcases for the other XRay opcodes too?

[duck-37]

llvm/test/CodeGen/AArch64/machine-outliner-patchable-exit.mir

5

Sure, but it's important to note that the test case for PATCHABLE_FUNCTION_ENTER won't fail

... outside of ARM32, where isMBBSafeToOutlineFrom is overriden without a call to the base class. I'll add a test for this there, and then submit a patch to refactor isMBBSafeToOutlineFrom as well.

[duck-37]

Looks like this was fixed in D147982.

llvm/lib/CodeGen/TargetInstrInfo.cpp

outliner::InstrType TargetInstrInfo::getOutliningType(
 
   // Some other special cases.
   switch (MI.getOpcode()) {
     case TargetOpcode::IMPLICIT_DEF:
     case TargetOpcode::KILL:
     case TargetOpcode::LIFETIME_START:
     case TargetOpcode::LIFETIME_END:
       return outliner::InstrType::Invisible;
+    case TargetOpcode::PATCHABLE_FUNCTION_ENTER:
+    case TargetOpcode::PATCHABLE_RET:
+    case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
+    case TargetOpcode::PATCHABLE_TAIL_CALL:
+    case TargetOpcode::PATCHABLE_EVENT_CALL:
+    case TargetOpcode::PATCHABLE_TYPED_EVENT_CALL:
+      // XRay pseudo-instructions can't safely be outlined, and
+      // shouldn't be either way due to their intended purpose.
+      return outliner::InstrType::Illegal;
     default:
       break;
   }
 
   // Is this a terminator for a basic block?
   if (MI.isTerminator()) {
     // If this is a branch to another block, we can't outline it.
     if (!MI.getParent()->succ_empty())

llvm/test/CodeGen/AArch64/machine-outliner-patchable-exit.mir

+# RUN: llc -mtriple aarch64 -run-pass=machine-outliner -verify-machineinstrs %s -o - | FileCheck %s
+# CHECK-NOT: OUTLINED_FUNCTION
+
+...
+---
+name:            foo1
+tracksRegLiveness: true
+machineFunctionInfo:
+  hasRedZone:      false
+body:             |
+  bb.0:
+    liveins: $x0
+    $x0 = ADDXri $x0, 0, 0
+    PATCHABLE_FUNCTION_EXIT
+    RET_ReallyLR implicit $x0
+
+...
+---
+name:            foo2
+tracksRegLiveness: true
+machineFunctionInfo:
+  hasRedZone:      false
+body:             |
+  bb.0:
+    liveins: $x0
+    $x0 = ADDXri $x0, 0, 0
+    PATCHABLE_FUNCTION_EXIT
+    RET_ReallyLR implicit $x0
+
+...