Split IndirectBr critical edges before PGO gen/use passes.

Summary:
The PGO gen/use passes currently fail with an assert failure if there's a
critical edge whose source is an IndirectBr instruction and that edge
needs to be instrumented.

To avoid this in certain cases, split IndirectBr critical edges in the PGO
gen/use passes. This works for blocks with single indirectbr predecessors,
but not for those with multiple indirectbr predecessors (splitting an
IndirectBr critical edge isn't always possible.)

Reviewers: davidxl, xur

Reviewed By: davidxl

Subscribers: efriedma, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D40699

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320511 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/include/llvm/Transforms/Utils/BasicBlockUtils.h b/include/llvm/Transforms/Utils/BasicBlockUtils.h
index d42c11f1d9f..74f75509f55 100644
--- a/include/llvm/Transforms/Utils/BasicBlockUtils.h
+++ b/include/llvm/Transforms/Utils/BasicBlockUtils.h
@@ -25,6 +25,8 @@
 
 namespace llvm {
 
+class BlockFrequencyInfo;
+class BranchProbabilityInfo;
 class DominatorTree;
 class Function;
 class Instruction;
@@ -301,7 +303,10 @@ Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
 // and D1 is the D block body. We can then duplicate D0 as D0A and D0B, and
 // create the following structure:
 // A -> D0A, B -> D0A, I -> D0B, D0A -> D1, D0B -> D1
-bool SplitIndirectBrCriticalEdges(Function &F);
+// If BPI and BFI aren't non-null, BPI/BFI will be updated accordingly.
+bool SplitIndirectBrCriticalEdges(Function &F,
+                                  BranchProbabilityInfo *BPI = nullptr,
+                                  BlockFrequencyInfo *BFI = nullptr);
 
 } // end namespace llvm