NewGVN: Rewrite DCE during elimination so we do it as well as old GVN did.

llvm-svn: 297428

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/include/llvm/Transforms/Utils/Local.h b/llvm/include/llvm/Transforms/Utils/Local.h
index 490a765c3fa..a747d2e8121 100644
--- a/llvm/include/llvm/Transforms/Utils/Local.h
+++ b/llvm/include/llvm/Transforms/Utils/Local.h
@@ -74,6 +74,12 @@ bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false,
 bool isInstructionTriviallyDead(Instruction *I,
                                 const TargetLibraryInfo *TLI = nullptr);
 
+/// Return true if the result produced by the instruction would have no side
+/// effects if it was not used. This is equivalent to checking whether
+/// isInstructionTriviallyDead would be true if the use count was 0.
+bool wouldInstructionBeTriviallyDead(Instruction *I,
+                                     const TargetLibraryInfo *TLI = nullptr);
+
 /// If the specified value is a trivially dead instruction, delete it.
 /// If that makes any of its operands trivially dead, delete them too,
 /// recursively. Return true if any instructions were deleted.