Update phi nodes in LowerTypeTests control flow simplification

[vlad.tsyrklevich]

Summary

D33925 added a control flow simplification for -O2 --lto-O0 builds that manually splits blocks and reassigns conditional branches but does not correctly update phi nodes. If the else case being branched to had incoming phi nodes the control-flow simplification would leave phi nodes in that BB with an unhandled predecessor.

[pcc]

LGTM

lib/Transforms/IPO/LowerTypeTests.cpp

638

Nit: rename to Phi.

lib/Transforms/IPO/LowerTypeTests.cpp

if (auto *Br = dyn_cast<BranchInst>(*CI->user_begin()))
       if (CI->getNextNode() == Br) {
         BasicBlock *Then = InitialBB->splitBasicBlock(CI->getIterator());
         BasicBlock *Else = Br->getSuccessor(1);
         BranchInst *NewBr = BranchInst::Create(Then, Else, OffsetInRange);
         NewBr->setMetadata(LLVMContext::MD_prof,
                            Br->getMetadata(LLVMContext::MD_prof));
         ReplaceInstWithInst(InitialBB->getTerminator(), NewBr);
 
+        // Update phis in Else resulting from InitialBB being split
+        for (auto &Phi : Else->phis())
+          Phi.addIncoming(Phi.getIncomingValueForBlock(Then), InitialBB);
+
         IRBuilder<> ThenB(CI);
         return createBitSetTest(ThenB, TIL, BitOffset);
       }
 
   IRBuilder<> ThenB(SplitBlockAndInsertIfThen(OffsetInRange, CI, false));
 
   // Now that we know that the offset is in range and aligned, load the
   // appropriate bit from the bitset.

test/Transforms/LowerTypeTests/simplify_phi.ll

+; Ensure that LowerTypeTests control flow simplification correctly handle phi nodes.
+; RUN: opt -S -lowertypetests -lowertypetests-summary-action=import -lowertypetests-read-summary=%S/Inputs/import.yaml < %s | FileCheck %s
+
+target datalayout = "e-p:64:64"
+
+declare i1 @llvm.type.test(i8* %ptr, metadata %bitset) nounwind readnone
+
+; CHECK: define i1 @bytearray7(i8* [[p:%.*]])
+define i1 @bytearray7(i8* %p) {
+  %x = call i1 @llvm.type.test(i8* %p, metadata !"bytearray7")
+  br i1 %x, label %t, label %f
+
+t:
+  br label %f
+
+f:
+  ; CHECK: %test = phi i1 [ false, %{{[0-9]+}} ], [ true, %t ], [ false, %0 ]
+  %test = phi i1 [ false, %0 ], [ true, %t ]
+  ret i1 %test
+}