Reenable tail duplication of bb with just an unconditional jump, but

don't remove blocks that have their address taken.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133659 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index d16369a4ca66cf036a1b460d97d28bdb74b69f8a..e5c23b36d298fd6c4a9da9f2a596e306e1fabdef 100644 (file)
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -207,7 +207,7 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
       // TailBB's immediate successors are now successors of those predecessors
       // which duplicated TailBB. Add the predecessors as sources to the PHI
       // instructions.
-      bool isDead = MBB->pred_empty();
+      bool isDead = MBB->pred_empty() && !MBB->hasAddressTaken();
       if (PreRegAlloc)
         UpdateSuccessorsPHIs(MBB, isDead, TDBBs, Succs);
 
@@ -568,9 +568,9 @@ bool
 TailDuplicatePass::isSimpleBB(MachineBasicBlock *TailBB) {
   if (TailBB->succ_size() != 1)
     return false;
-  MachineBasicBlock::iterator I = TailBB->getFirstNonPHI();
+  MachineBasicBlock::iterator I = TailBB->begin();
   MachineBasicBlock::iterator E = TailBB->end();
-  while (I->isDebugValue() && I != E)
+  while (I != E && I->isDebugValue())
     ++I;
   if (I == E)
     return true;
@@ -712,7 +712,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
   DenseSet<unsigned> UsedByPhi;
   getRegsUsedByPHIs(*TailBB, &UsedByPhi);
 
-  if (0 && isSimpleBB(TailBB))
+  if (isSimpleBB(TailBB))
     return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
 
   // Iterate through all the unique predecessors and tail-duplicate this

diff --git a/test/CodeGen/X86/tail-dup-addr.ll b/test/CodeGen/X86/tail-dup-addr.ll
new file mode 100644 (file)
index 0000000..c5a105c
--- /dev/null
+++ b/test/CodeGen/X86/tail-dup-addr.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
+
+; Test that we don't drop a block that has its address taken.
+
+; CHECK: Ltmp1:                                  ## Block address taken
+; CHECK: Ltmp2:                                  ## Block address taken
+
+@a = common global i32 0, align 4
+@p = common global i8* null, align 8
+
+define void @foo() noreturn nounwind uwtable ssp {
+entry:
+  %tmp = load i32* @a, align 4
+  %foo = icmp eq i32 0, %tmp
+  br i1 %foo, label %sw.bb, label %sw.default
+
+sw.bb:                                            ; preds = %entry
+  store i8* blockaddress(@foo, %sw.bb1), i8** @p, align 8
+  br label %sw.bb1
+
+sw.bb1:                                           ; preds = %sw.default, %sw.bb, %entry
+  store i8* blockaddress(@foo, %sw.default), i8** @p, align 8
+  br label %sw.default
+
+sw.default:                                       ; preds = %sw.bb1, %entry
+  store i8* blockaddress(@foo, %sw.bb1), i8** @p, align 8
+  br label %sw.bb1
+}