Teach taildup to update livein set. rdar://11538365

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157663 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 165 insertions, 0 deletions

diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index 3e203850f9..d077b09193 100644
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -20,7 +20,9 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/MachineSSAUpdater.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -57,8 +59,10 @@ namespace {
   /// TailDuplicatePass - Perform tail duplication.
   class TailDuplicatePass : public MachineFunctionPass {
     const TargetInstrInfo *TII;
+    const TargetRegisterInfo *TRI;
     MachineModuleInfo *MMI;
     MachineRegisterInfo *MRI;
+    RegScavenger *RS;
     bool PreRegAlloc;
 
     // SSAUpdateVRs - A list of virtual registers for which to update SSA form.
@@ -124,9 +128,13 @@ INITIALIZE_PASS(TailDuplicatePass, "tailduplication", "Tail Duplication",
 
 bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
   TII = MF.getTarget().getInstrInfo();
+  TRI = MF.getTarget().getRegisterInfo();
   MRI = &MF.getRegInfo();
   MMI = getAnalysisIfAvailable<MachineModuleInfo>();
   PreRegAlloc = MRI->isSSA();
+  RS = NULL;
+  if (MRI->tracksLiveness() && TRI->trackLivenessAfterRegAlloc(MF))
+    RS = new RegScavenger();
 
   bool MadeChange = false;
   while (TailDuplicateBlocks(MF))
@@ -777,6 +785,23 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
     // Remove PredBB's unconditional branch.
     TII->RemoveBranch(*PredBB);
 
+    if (RS && !TailBB->livein_empty()) {
+      // Update PredBB livein.
+      RS->enterBasicBlock(PredBB);
+      if (!PredBB->empty())
+        RS->forward(prior(PredBB->end()));
+      BitVector RegsLiveAtExit(TRI->getNumRegs());
+      RS->getRegsUsed(RegsLiveAtExit, false);
+      for (MachineBasicBlock::livein_iterator I = TailBB->livein_begin(),
+             E = TailBB->livein_end(); I != E; ++I) {
+        if (!RegsLiveAtExit[*I])
+          // If a register is previously livein to the tail but it's not live
+          // at the end of predecessor BB, then it should be added to its
+          // livein list.
+          PredBB->addLiveIn(*I);
+      }
+    }
+
     // Clone the contents of TailBB into PredBB.
     DenseMap<unsigned, unsigned> LocalVRMap;
     SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos;
diff --git a/test/CodeGen/ARM/2012-05-29-TailDupBug.ll b/test/CodeGen/ARM/2012-05-29-TailDupBug.ll
new file mode 100644
index 0000000000..1a57f04f64
--- /dev/null
+++ b/test/CodeGen/ARM/2012-05-29-TailDupBug.ll
@@ -0,0 +1,140 @@
+; RUN: llc -mtriple=thumbv7-apple-ios -mcpu=cortex-a8 -verify-machineinstrs < %s
+
+; Teach taildup to update livein set to appease verifier.
+; rdar://11538365
+
+%struct.__CFString.2 = type opaque
+
+declare void @CFRelease(i8*)
+
+define hidden fastcc i32 @t() ssp {
+entry:
+  %mylocale.i.i = alloca [256 x i8], align 1
+  br i1 undef, label %return, label %CFStringIsHyphenationAvailableForLocale.exit
+
+CFStringIsHyphenationAvailableForLocale.exit:     ; preds = %entry
+  br i1 undef, label %return, label %if.end
+
+if.end:                                           ; preds = %CFStringIsHyphenationAvailableForLocale.exit
+  br i1 undef, label %if.end8.thread.i, label %if.then.i
+
+if.then.i:                                        ; preds = %if.end
+  br i1 undef, label %if.end8.thread.i, label %if.end8.i
+
+if.end8.thread.i:                                 ; preds = %if.then.i, %if.end
+  unreachable
+
+if.end8.i:                                        ; preds = %if.then.i
+  br i1 undef, label %if.then11.i, label %__CFHyphenationPullTokenizer.exit
+
+if.then11.i:                                      ; preds = %if.end8.i
+  unreachable
+
+__CFHyphenationPullTokenizer.exit:                ; preds = %if.end8.i
+  br i1 undef, label %if.end68, label %if.then3
+
+if.then3:                                         ; preds = %__CFHyphenationPullTokenizer.exit
+  br i1 undef, label %cond.end, label %cond.false
+
+cond.false:                                       ; preds = %if.then3
+  br label %cond.end
+
+cond.end:                                         ; preds = %cond.false, %if.then3
+  br i1 undef, label %while.end, label %while.body
+
+while.body:                                       ; preds = %cond.end
+  unreachable
+
+while.end:                                        ; preds = %cond.end
+  br i1 undef, label %if.end5.i, label %if.then.i16
+
+if.then.i16:                                      ; preds = %while.end
+  br i1 undef, label %if.then4.i, label %if.end5.i
+
+if.then4.i:                                       ; preds = %if.then.i16
+  br i1 false, label %cleanup.thread, label %if.end.i20
+
+if.end5.i:                                        ; preds = %if.then.i16, %while.end
+  unreachable
+
+if.end.i20:                                       ; preds = %if.then4.i
+  br label %for.body.i146.i
+
+for.body.i146.i:                                  ; preds = %for.body.i146.i, %if.end.i20
+  br i1 undef, label %if.end20.i, label %for.body.i146.i
+
+if.end20.i:                                       ; preds = %for.body.i146.i
+  br i1 undef, label %cleanup.thread, label %if.end23.i
+
+if.end23.i:                                       ; preds = %if.end20.i
+  br label %for.body.i94.i
+
+for.body.i94.i:                                   ; preds = %for.body.i94.i, %if.end23.i
+  br i1 undef, label %if.then28.i, label %for.body.i94.i
+
+if.then28.i:                                      ; preds = %for.body.i94.i
+  br i1 undef, label %cond.true.i26, label %land.lhs.true
+
+cond.true.i26:                                    ; preds = %if.then28.i
+  br label %land.lhs.true
+
+land.lhs.true:                                    ; preds = %cond.true.i26, %if.then28.i
+  br i1 false, label %cleanup.thread, label %if.end35
+
+if.end35:                                         ; preds = %land.lhs.true
+  br i1 undef, label %cleanup.thread, label %if.end45
+
+if.end45:                                         ; preds = %if.end35
+  br i1 undef, label %if.then50, label %if.end.i37
+
+if.end.i37:                                       ; preds = %if.end45
+  br label %if.then50
+
+if.then50:                                        ; preds = %if.end.i37, %if.end45
+  br i1 undef, label %__CFHyphenationGetHyphensForString.exit, label %if.end.i
+
+if.end.i:                                         ; preds = %if.then50
+  br i1 undef, label %cleanup.i, label %cond.true.i
+
+cond.true.i:                                      ; preds = %if.end.i
+  br i1 undef, label %for.cond16.preheader.i, label %for.cond57.preheader.i
+
+for.cond16.preheader.i:                           ; preds = %cond.true.i
+  %cmp1791.i = icmp sgt i32 undef, 1
+  br i1 %cmp1791.i, label %for.body18.i, label %for.cond57.preheader.i
+
+for.cond57.preheader.i:                           ; preds = %for.cond16.preheader.i, %cond.true.i
+  %sub69.i = add i32 undef, -2
+  br label %cleanup.i
+
+for.body18.i:                                     ; preds = %for.cond16.preheader.i
+  store i16 0, i16* undef, align 2
+  br label %while.body.i
+
+while.body.i:                                     ; preds = %while.body.i, %for.body18.i
+  br label %while.body.i
+
+cleanup.i:                                        ; preds = %for.cond57.preheader.i, %if.end.i
+  br label %__CFHyphenationGetHyphensForString.exit
+
+__CFHyphenationGetHyphensForString.exit:          ; preds = %cleanup.i, %if.then50
+  %retval.1.i = phi i32 [ 0, %cleanup.i ], [ -1, %if.then50 ]
+  %phitmp = bitcast %struct.__CFString.2* null to i8*
+  br label %if.end68
+
+cleanup.thread:                                   ; preds = %if.end35, %land.lhs.true, %if.end20.i, %if.then4.i
+  call void @llvm.stackrestore(i8* null)
+  br label %return
+
+if.end68:                                         ; preds = %__CFHyphenationGetHyphensForString.exit, %__CFHyphenationPullTokenizer.exit
+  %hyphenCount.2 = phi i32 [ %retval.1.i, %__CFHyphenationGetHyphensForString.exit ], [ 0, %__CFHyphenationPullTokenizer.exit ]
+  %_token.1 = phi i8* [ %phitmp, %__CFHyphenationGetHyphensForString.exit ], [ undef, %__CFHyphenationPullTokenizer.exit ]
+  call void @CFRelease(i8* %_token.1)
+  br label %return
+
+return:                                           ; preds = %if.end68, %cleanup.thread, %CFStringIsHyphenationAvailableForLocale.exit, %entry
+  %retval.1 = phi i32 [ %hyphenCount.2, %if.end68 ], [ -1, %CFStringIsHyphenationAvailableForLocale.exit ], [ -1, %cleanup.thread ], [ -1, %entry ]
+  ret i32 %retval.1
+}
+
+declare void @llvm.stackrestore(i8*) nounwind