From 6a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Sat, 4 Jun 2011 09:42:04 +0000
Subject: [PATCH] If the block that we're threading through is jumped to by an
 indirect branch, then we don't want to set the destination in the indirect
 branch to the destination. This is because the indirect branch needs its
 destinations to have had their block addresses taken. This isn't so of the
 new critical edge that's split during this process. If it turns out that the
 destination block has only one predecessor, and that being a BB with an
 indirect branch, then it won't be marked as 'used' and may be removed.
 PR10072

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132638 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/SimplifyCFG.cpp      |  4 +-
 test/Transforms/SimplifyCFG/indirectbr.ll | 69 +++++++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 5ab9a2877cd..6df846cbd18 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1171,6 +1171,8 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) {
     BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue());
     
     if (RealDest == BB) continue;  // Skip self loops.
+    // Skip if the predecessor's terminator is an indirect branch.
+    if (isa<IndirectBrInst>(PredBB->getTerminator())) continue;
     
     // The dest block might have PHI nodes, other predecessors and other
     // difficult cases.  Instead of being smart about this, just insert a new
@@ -1226,7 +1228,7 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) {
         BB->removePredecessor(PredBB);
         PredBBTI->setSuccessor(i, EdgeBB);
       }
-    
+
     // Recurse, simplifying any other constants.
     return FoldCondBranchOnPHI(BI, TD) | true;
   }
diff --git a/test/Transforms/SimplifyCFG/indirectbr.ll b/test/Transforms/SimplifyCFG/indirectbr.ll
index 7fb4def5b93..7853e9abd2e 100644
--- a/test/Transforms/SimplifyCFG/indirectbr.ll
+++ b/test/Transforms/SimplifyCFG/indirectbr.ll
@@ -180,3 +180,72 @@ L3:
 ; before SimplifyCFG even looks at the indirectbr.
   indirectbr i8* %anchor, [label %L1, label %L2]
 }
+
+; PR10072
+
+@xblkx.bbs = internal unnamed_addr constant [9 x i8*] [i8* blockaddress(@indbrtest7, %xblkx.begin), i8* blockaddress(@indbrtest7, %xblkx.begin3), i8* blockaddress(@indbrtest7, %xblkx.begin4), i8* blockaddress(@indbrtest7, %xblkx.begin5), i8* blockaddress(@indbrtest7, %xblkx.begin6), i8* blockaddress(@indbrtest7, %xblkx.begin7), i8* blockaddress(@indbrtest7, %xblkx.begin8), i8* blockaddress(@indbrtest7, %xblkx.begin9), i8* blockaddress(@indbrtest7, %xblkx.end)]
+
+define void @indbrtest7() {
+escape-string.top:
+  %xval202x = call i32 @xfunc5x()
+  br label %xlab5x
+
+xlab8x:                                           ; preds = %xlab5x
+  %xvaluex = call i32 @xselectorx()
+  %xblkx.x = getelementptr [9 x i8*]* @xblkx.bbs, i32 0, i32 %xvaluex
+  %xblkx.load = load i8** %xblkx.x
+  indirectbr i8* %xblkx.load, [label %xblkx.begin, label %xblkx.begin3, label %xblkx.begin4, label %xblkx.begin5, label %xblkx.begin6, label %xblkx.begin7, label %xblkx.begin8, label %xblkx.begin9, label %xblkx.end]
+
+xblkx.begin:
+  br label %xblkx.end
+
+xblkx.begin3:
+  br label %xblkx.end
+
+xblkx.begin4:
+  br label %xblkx.end
+
+xblkx.begin5:
+  br label %xblkx.end
+
+xblkx.begin6:
+  br label %xblkx.end
+
+xblkx.begin7:
+  br label %xblkx.end
+
+xblkx.begin8:
+  br label %xblkx.end
+
+xblkx.begin9:
+  br label %xblkx.end
+
+xblkx.end:
+  %yes.0 = phi i1 [ false, %xblkx.begin ], [ true, %xlab8x ], [ false, %xblkx.begin9 ], [ false, %xblkx.begin8 ], [ false, %xblkx.begin7 ], [ false, %xblkx.begin6 ], [ false, %xblkx.begin5 ], [ true, %xblkx.begin4 ], [ false, %xblkx.begin3 ]
+  br i1 %yes.0, label %v2j, label %xlab17x
+
+v2j:
+; CHECK: %xunusedx = call i32 @xactionx()
+  %xunusedx = call i32 @xactionx()
+  br label %xlab4x
+
+xlab17x:
+  br label %xlab4x
+
+xlab4x:
+  %incr19 = add i32 %xval704x.0, 1
+  br label %xlab5x
+
+xlab5x:
+  %xval704x.0 = phi i32 [ 0, %escape-string.top ], [ %incr19, %xlab4x ]
+  %xval10x = icmp ult i32 %xval704x.0, %xval202x
+  br i1 %xval10x, label %xlab8x, label %xlab9x
+
+xlab9x:
+  ret void
+}
+
+declare i32 @xfunc5x()
+declare i8 @xfunc7x()
+declare i32 @xselectorx()
+declare i32 @xactionx()