Merge commit '7c5f104e4549' from llvm.org/main into next

Author: git apple-llvm automerger

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -113,10 +113,6 @@ static cl::opt<unsigned> TwoEntryPHINodeFoldingThreshold(
              "to speculatively execute to fold a 2-entry PHI node into a "
              "select (default = 4)"));
 
-static cl::opt<bool> DupRet(
-    "simplifycfg-dup-ret", cl::Hidden, cl::init(false),
-    cl::desc("Duplicate return instructions into unconditional branches"));
-
 static cl::opt<bool>
     HoistCommon("simplifycfg-hoist-common", cl::Hidden, cl::init(true),
                 cl::desc("Hoist common instructions up to the parent block"));
@@ -4638,32 +4634,12 @@ bool SimplifyCFGOpt::simplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
     return false;
 
   // Find predecessors that end with branches.
-  SmallVector<BasicBlock *, 8> UncondBranchPreds;
   SmallVector<BranchInst *, 8> CondBranchPreds;
   for (BasicBlock *P : predecessors(BB)) {
     Instruction *PTI = P->getTerminator();
-    if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) {
-      if (BI->isUnconditional())
-        UncondBranchPreds.push_back(P);
-      else
+    if (BranchInst *BI = dyn_cast<BranchInst>(PTI))
+      if (BI->isConditional())
         CondBranchPreds.push_back(BI);
-    }
-  }
-
-  // If we found some, do the transformation!
-  if (!UncondBranchPreds.empty() && DupRet) {
-    while (!UncondBranchPreds.empty()) {
-      BasicBlock *Pred = UncondBranchPreds.pop_back_val();
-      LLVM_DEBUG(dbgs() << "FOLDING: " << *BB
-                        << "INTO UNCOND BRANCH PRED: " << *Pred);
-      (void)FoldReturnIntoUncondBranch(RI, BB, Pred, DTU);
-    }
-
-    // If we eliminated all predecessors of the block, delete the block now.
-    if (pred_empty(BB))
-      DeleteDeadBlock(BB, DTU);
-
-    return true;
   }
 
   // Check out all of the conditional branches going to this return

llvm/test/Transforms/SimplifyCFG/duplicate-ret-into-uncond-br.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -simplifycfg-dup-ret -S | FileCheck %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
 
 declare void @bar()
 declare void @baz()

llvm/test/Transforms/SimplifyCFG/merge-duplicate-conditional-ret-val.ll

@@ -1,6 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck --check-prefixes=CHECK,NODUPRET %s
-; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -simplifycfg-dup-ret -S | FileCheck --check-prefixes=CHECK,DUPRET %s
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck --check-prefixes=CHECK %s
 ; RUN: opt < %s -debugify -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck --check-prefixes=DBGINFO %s
 
 define i32 @test1(i1 %C) {
@@ -24,12 +23,9 @@ F:              ; preds = %entry
 }
 
 define void @test2(i1 %C) {
-; NODUPRET-LABEL: @test2(
-; NODUPRET-NEXT:  common.ret:
-; NODUPRET-NEXT:    ret void
-;
-; DUPRET-LABEL: @test2(
-; DUPRET-NEXT:    ret void
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  common.ret:
+; CHECK-NEXT:    ret void
 ;
 ; DBGINFO-LABEL: @test2(
 ; DBGINFO-NEXT:  common.ret:
@@ -48,32 +44,20 @@ declare void @sideeffect1()
 declare void @sideeffect2()
 
 define i32 @test3(i1 %C0, i1 %C1, i32 %v0, i32 %v1, i32 %v2) {
-; NODUPRET-LABEL: @test3(
-; NODUPRET-NEXT:  entry:
-; NODUPRET-NEXT:    call void @sideeffect0()
-; NODUPRET-NEXT:    br i1 [[C0:%.*]], label [[T:%.*]], label [[F:%.*]]
-; NODUPRET:       end:
-; NODUPRET-NEXT:    [[R:%.*]] = phi i32 [ [[V2:%.*]], [[F]] ], [ [[SPEC_SELECT:%.*]], [[T]] ]
-; NODUPRET-NEXT:    ret i32 [[R]]
-; NODUPRET:       T:
-; NODUPRET-NEXT:    call void @sideeffect1()
-; NODUPRET-NEXT:    [[SPEC_SELECT]] = select i1 [[C1:%.*]], i32 [[V0:%.*]], i32 [[V1:%.*]]
-; NODUPRET-NEXT:    br label [[END:%.*]]
-; NODUPRET:       F:
-; NODUPRET-NEXT:    call void @sideeffect2()
-; NODUPRET-NEXT:    br label [[END]]
-;
-; DUPRET-LABEL: @test3(
-; DUPRET-NEXT:  entry:
-; DUPRET-NEXT:    call void @sideeffect0()
-; DUPRET-NEXT:    br i1 [[C0:%.*]], label [[T:%.*]], label [[F:%.*]]
-; DUPRET:       T:
-; DUPRET-NEXT:    call void @sideeffect1()
-; DUPRET-NEXT:    [[RETVAL:%.*]] = select i1 [[C1:%.*]], i32 [[V0:%.*]], i32 [[V1:%.*]]
-; DUPRET-NEXT:    ret i32 [[RETVAL]]
-; DUPRET:       F:
-; DUPRET-NEXT:    call void @sideeffect2()
-; DUPRET-NEXT:    ret i32 [[V2:%.*]]
+; CHECK-LABEL: @test3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @sideeffect0()
+; CHECK-NEXT:    br i1 [[C0:%.*]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       end:
+; CHECK-NEXT:    [[R:%.*]] = phi i32 [ [[V2:%.*]], [[F]] ], [ [[SPEC_SELECT:%.*]], [[T]] ]
+; CHECK-NEXT:    ret i32 [[R]]
+; CHECK:       T:
+; CHECK-NEXT:    call void @sideeffect1()
+; CHECK-NEXT:    [[SPEC_SELECT]] = select i1 [[C1:%.*]], i32 [[V0:%.*]], i32 [[V1:%.*]]
+; CHECK-NEXT:    br label [[END:%.*]]
+; CHECK:       F:
+; CHECK-NEXT:    call void @sideeffect2()
+; CHECK-NEXT:    br label [[END]]
 ;
 ; DBGINFO-LABEL: @test3(
 ; DBGINFO-NEXT:  entry: