[FastISel] Fix insertion of unconditional branches during FastISel

The insertion of an unconditional branch during FastISel can differ depending on
building with or without debug information. This happens because FastISel::fastEmitBranch
emits an unconditional branch depending on the size of the current basic block
without distinguishing between debug and non-debug instructions.

This patch fixes this issue by ignoring debug instructions when getting the size
of the basic block.

Reviewers: aprantl

Reviewed By: aprantl

Subscribers: ormris, aprantl, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67703

llvm-svn: 372389

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index f8352ca2fe6..8904283ff8d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1677,11 +1677,11 @@ bool FastISel::selectInstruction(const Instruction *I) {
 /// (fall-through) successor, and update the CFG.
 void FastISel::fastEmitBranch(MachineBasicBlock *MSucc,
                               const DebugLoc &DbgLoc) {
-  if (FuncInfo.MBB->getBasicBlock()->size() > 1 &&
+  if (FuncInfo.MBB->getBasicBlock()->sizeWithoutDebug() > 1 &&
       FuncInfo.MBB->isLayoutSuccessor(MSucc)) {
-    // For more accurate line information if this is the only instruction
-    // in the block then emit it, otherwise we have the unconditional
-    // fall-through case, which needs no instructions.
+    // For more accurate line information if this is the only non-debug
+    // instruction in the block then emit it, otherwise we have the
+    // unconditional fall-through case, which needs no instructions.
   } else {
     // The unconditional branch case.
     TII.insertBranch(*FuncInfo.MBB, MSucc, nullptr,