[MachineVerifier][GlobalISel] Check that branches have a MBB operand or are declared indirect. Add missing properties to G_BRJT, G_BRINDIRECT

Summary:
Teach MachineVerifier to check branches for MBB operands if they are not declared indirect.

Add `isBarrier`, `isIndirectBranch` to `G_BRINDIRECT` and `G_BRJT`.
Without these, `MachineInstr.isConditionalBranch()` was giving a
false-positive for those instructions.

Reviewers: aemerson, qcolombet, dsanders, arsenm

Reviewed By: dsanders

Subscribers: hiraditya, wdng, simoncook, s.egerton, arsenm, rovka, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81587

1 files changed, 16 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index c4776261..5929549 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -863,6 +863,22 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
   const MCInstrDesc &MCID = MI->getDesc();
   unsigned NumOps = MI->getNumOperands();
 
+  // Branches must reference a basic block if they are not indirect
+  if (MI->isBranch() && !MI->isIndirectBranch()) {
+    bool HasMBB = false;
+    for (const MachineOperand &Op : MI->operands()) {
+      if (Op.isMBB()) {
+        HasMBB = true;
+        break;
+      }
+    }
+
+    if (!HasMBB)
+      report("Branch instruction is missing a basic block operand or "
+             "isIndirectBranch property",
+             MI);
+  }
+
   // Check types.
   SmallVector<LLT, 4> Types;
   for (unsigned I = 0, E = std::min(MCID.getNumOperands(), NumOps);