[PATCH] D36012: Update phi nodes in LowerTypeTests control flow simplification

[Vlad Tsyrklevich via Phabricator via llvm-commits]

vlad.tsyrklevich created this revision.
Herald added a subscriber: mehdi_amini.

https://reviews.llvm.org/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.


https://reviews.llvm.org/D36012

Files:
  lib/Transforms/IPO/LowerTypeTests.cpp
  test/Transforms/LowerTypeTests/simplify_phi.ll


Index: test/Transforms/LowerTypeTests/simplify_phi.ll
===================================================================
--- /dev/null
+++ test/Transforms/LowerTypeTests/simplify_phi.ll
@@ -0,0 +1,20 @@
+; 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
+}
Index: lib/Transforms/IPO/LowerTypeTests.cpp
===================================================================
--- lib/Transforms/IPO/LowerTypeTests.cpp
+++ lib/Transforms/IPO/LowerTypeTests.cpp
@@ -634,6 +634,10 @@
                            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);
       }


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