Lower widenable_conditions in CGP

This ensures that if we make it to the backend w/o lowering widenable_conditions first, that we generate correct code. Doing it in CGP - instead of isel - let's us fold control flow before hitting block local instruction selection.

Differential Revision: https://reviews.llvm.org/D57473

llvm-svn: 352779

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index e382798..7d5d839 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1703,6 +1703,20 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
   if (II) {
     switch (II->getIntrinsicID()) {
     default: break;
+    case Intrinsic::experimental_widenable_condition: {
+      // Give up on future widening oppurtunties so that we can fold away dead
+      // paths and merge blocks before going into block-local instruction
+      // selection.   
+      if (II->use_empty()) {
+        II->eraseFromParent();
+        return true;
+      }
+      Constant *RetVal = ConstantInt::getTrue(II->getContext());
+      resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
+        replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
+      });
+      return true;
+    }
     case Intrinsic::objectsize: {
       // Lower all uses of llvm.objectsize.*
       Value *RetVal =