Revert "[SimplifyCFG] Fix bootstrap failure after r280220"

This reverts commit r280228. r280216 caused buildbot failures - backing out the entire sequence.

llvm-svn: 280231

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 537bc76..3de6c60 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1444,7 +1444,7 @@ static bool canSinkInstructions(
 // Assuming canSinkLastInstruction(Blocks) has returned true, sink the last
 // instruction of every block in Blocks to their common successor, commoning
 // into one instruction.
-static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
+static void sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
   auto *BBEnd = Blocks[0]->getTerminator()->getSuccessor(0);
 
   // canSinkLastInstruction returning true guarantees that every block has at
@@ -1453,22 +1453,9 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
   for (auto *BB : Blocks)
     Insts.push_back(BB->getTerminator()->getPrevNode());
 
-  // The only checking we need to do now is that all users of all instructions
-  // are the same PHI node. canSinkLastInstruction should have checked this but
-  // it is slightly over-aggressive - it gets confused by commutative instructions
-  // so double-check it here.
+  // We don't need to do any checking here; canSinkLastInstruction should have
+  // done it all for us.
   Instruction *I0 = Insts.front();
-  if (!isa<StoreInst>(I0)) {
-    auto *PNUse = dyn_cast<PHINode>(*I0->user_begin());
-    if (!all_of(Insts, [&PNUse](const Instruction *I) -> bool {
-          auto *U = cast<Instruction>(*I->user_begin());
-          return U == PNUse || U->getParent() == I->getParent();
-        }))
-      return false;
-  }
-  
-  // We don't need to do any more checking here; canSinkLastInstruction should
-  // have done it all for us.
   SmallVector<Value*, 4> NewOperands;
   for (unsigned O = 0, E = I0->getNumOperands(); O != E; ++O) {
     // This check is different to that in canSinkLastInstruction. There, we
@@ -1520,8 +1507,6 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
   for (auto *I : Insts)
     if (I != I0)
       I->eraseFromParent();
-
-  return true;
 }
 
 namespace {
@@ -1654,7 +1639,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
   LockstepReverseIterator LRI(UnconditionalPreds);
   while (LRI.isValid() &&
          canSinkInstructions(*LRI, PHIOperands)) {
-    DEBUG(dbgs() << "SINK: instruction can be sunk: " << *(*LRI)[0] << "\n");
+    DEBUG(dbgs() << "SINK: instruction can be sunk: " << (*LRI)[0] << "\n");
     InstructionsToSink.insert((*LRI).begin(), (*LRI).end());
     ++ScanIdx;
     --LRI;
@@ -1713,8 +1698,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
       break;
     }
     
-    if (!sinkLastInstruction(UnconditionalPreds))
-      return Changed;
+    sinkLastInstruction(UnconditionalPreds);
     NumSinkCommons++;
     Changed = true;
   }

diff --git a/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll b/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
index dc51264..9f87d3b 100644 (file)
--- a/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
+++ b/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
@@ -560,29 +560,6 @@ if.end:
 ; CHECK: store
 ; CHECK: store
 
-define zeroext i1 @test19(i1 zeroext %flag, i32* %i4, i32* %m, i32* %n) {
-entry:
-  br i1 %flag, label %if.then, label %if.else
-
-if.then:
-  %tmp1 = load i32, i32* %i4
-  %tmp2 = add i32 %tmp1, -1
-  store i32 %tmp2, i32* %i4
-  br label %if.end
-
-if.else:
-  %tmp3 = load i32, i32* %m
-  %tmp4 = load i32, i32* %n
-  %tmp5 = add i32 %tmp3, %tmp4
-  store i32 %tmp5, i32* %i4
-  br label %if.end
-
-if.end:
-  ret i1 true
-}
-
-; No checks for test19 - just ensure it doesn't crash!
-
 ; CHECK: !0 = !{!1, !1, i64 0}
 ; CHECK: !1 = !{!"float", !2}
 ; CHECK: !2 = !{!"an example type tree"}