Avoid adding PHI arguments for a predecessor that has gone away when a BRCOND was constant folded.

This fixes PR5980.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93184 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -1017,8 +1017,7 @@ SelectionDAGISel::FinishBasicBlock() {
       for (unsigned j = 0, ej = SDB->BitTestCases[i].Cases.size();
            j != ej; ++j) {
         MachineBasicBlock* cBB = SDB->BitTestCases[i].Cases[j].ThisBB;
-        if (cBB->succ_end() !=
+        if (cBB->isSuccessor(PHIBB)) {
-            std::find(cBB->succ_begin(),cBB->succ_end(), PHIBB)) {
           PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second,
                                                     false));
           PHI->addOperand(MachineOperand::CreateMBB(cBB));
@@ -1067,7 +1066,7 @@ SelectionDAGISel::FinishBasicBlock() {
           (MachineOperand::CreateMBB(SDB->JTCases[i].first.HeaderBB));
       }
       // JT BB. Just iterate over successors here
-      if (BB->succ_end() != std::find(BB->succ_begin(),BB->succ_end(), PHIBB)) {
+      if (BB->isSuccessor(PHIBB)) {
         PHI->addOperand
           (MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second, false));
         PHI->addOperand(MachineOperand::CreateMBB(BB));
@@ -1113,20 +1112,26 @@ SelectionDAGISel::FinishBasicBlock() {
         SDB->EdgeMapping.find(BB);
       if (EI != SDB->EdgeMapping.end())
         ThisBB = EI->second;
+
+      // BB may have been removed from the CFG if a branch was constant folded.
+      if (ThisBB->isSuccessor(BB)) {
         for (MachineBasicBlock::iterator Phi = BB->begin();
-           Phi != BB->end() && Phi->getOpcode() == TargetInstrInfo::PHI; ++Phi){
+             Phi != BB->end() && Phi->getOpcode() == TargetInstrInfo::PHI;
-        // This value for this PHI node is recorded in PHINodesToUpdate, get it.
+             ++Phi) {
+          // This value for this PHI node is recorded in PHINodesToUpdate.
           for (unsigned pn = 0; ; ++pn) {
             assert(pn != SDB->PHINodesToUpdate.size() &&
                    "Didn't find PHI entry!");
             if (SDB->PHINodesToUpdate[pn].first == Phi) {
-            Phi->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pn].
+              Phi->addOperand(MachineOperand::
-                                                      second, false));
+                              CreateReg(SDB->PHINodesToUpdate[pn].second,
+                                        false));
               Phi->addOperand(MachineOperand::CreateMBB(ThisBB));
               break;
             }
           }
         }
+      }
 
       // Don't process RHS if same block as LHS.
       if (BB == SDB->SwitchCases[i].FalseBB)

test/CodeGen/X86/2010-01-11-ExtraPHIArg.ll

@@ -0,0 +1,97 @@
+; RUN: llc -verify-machineinstrs < %s
+;
+; The lowering of a switch combined with constand folding would leave spurious extra arguments on a PHI instruction.
+;
+target triple = "x86_64-apple-darwin10"
+
+define void @foo() {
+  br label %cond_true813.i
+
+cond_true813.i:                                   ; preds = %0
+  br i1 false, label %cond_true818.i, label %cond_next1146.i
+
+cond_true818.i:                                   ; preds = %cond_true813.i
+  br i1 false, label %recog_memoized.exit52, label %cond_next1146.i
+
+recog_memoized.exit52:                            ; preds = %cond_true818.i
+  switch i32 0, label %bb886.i.preheader [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i
+    i32 103, label %bb874.i
+    i32 114, label %bb874.i
+  ]
+
+bb857.i:                                          ; preds = %bb886.i, %bb866.i
+  %tmp862.i494.24 = phi i8* [ null, %bb866.i ], [ %tmp862.i494.26, %bb886.i ] ; <i8*> [#uses=1]
+  switch i32 0, label %bb886.i.preheader [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i
+    i32 103, label %bb874.i
+    i32 114, label %bb874.i
+  ]
+
+bb866.i.loopexit:                                 ; preds = %bb874.i
+  br label %bb866.i
+
+bb866.i.loopexit31:                               ; preds = %cond_true903.i
+  br label %bb866.i
+
+bb866.i:                                          ; preds = %bb866.i.loopexit31, %bb866.i.loopexit, %bb857.i, %recog_memoized.exit52
+  br i1 false, label %bb907.i, label %bb857.i
+
+bb874.i.preheader.loopexit:                       ; preds = %cond_true903.i, %cond_true903.i
+  ret void
+
+bb874.i:                                          ; preds = %bb857.i, %bb857.i, %recog_memoized.exit52, %recog_memoized.exit52
+  switch i32 0, label %bb886.i.preheader.loopexit [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i.loopexit
+    i32 103, label %bb874.i.backedge
+    i32 114, label %bb874.i.backedge
+  ]
+
+bb874.i.backedge:                                 ; preds = %bb874.i, %bb874.i
+  ret void
+
+bb886.i.preheader.loopexit:                       ; preds = %bb874.i
+  ret void
+
+bb886.i.preheader:                                ; preds = %bb857.i, %recog_memoized.exit52
+  %tmp862.i494.26 = phi i8* [ undef, %recog_memoized.exit52 ], [ %tmp862.i494.24, %bb857.i ] ; <i8*> [#uses=1]
+  br label %bb886.i
+
+bb886.i:                                          ; preds = %cond_true903.i, %bb886.i.preheader
+  br i1 false, label %bb857.i, label %cond_true903.i
+
+cond_true903.i:                                   ; preds = %bb886.i
+  switch i32 0, label %bb886.i [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i.loopexit31
+    i32 103, label %bb874.i.preheader.loopexit
+    i32 114, label %bb874.i.preheader.loopexit
+  ]
+
+bb907.i:                                          ; preds = %cond_true903.i, %bb874.i, %bb866.i, %bb857.i, %recog_memoized.exit52
+  br i1 false, label %cond_next1146.i, label %cond_true910.i
+
+cond_true910.i:                                   ; preds = %bb907.i
+  ret void
+
+cond_next1146.i:                                  ; preds = %bb907.i, %cond_true818.i, %cond_true813.i
+  ret void
+
+bb2060.i:                                         ; No predecessors!
+  br i1 false, label %cond_true2064.i, label %bb2067.i
+
+cond_true2064.i:                                  ; preds = %bb2060.i
+  unreachable
+
+bb2067.i:                                         ; preds = %bb2060.i
+  ret void
+
+cond_next3473:                                    ; No predecessors!
+  ret void
+
+cond_next3521:                                    ; No predecessors!
+  ret void
+}