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

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 5ab9a2877cd503f3b834be873ce64467c03cea1f..6df846cbd18fd03cf0b54298a00a89450af75b0c 100644 (file)
--- 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 7fb4def5b932fc6be7aa21e406739d4c2770304a..7853e9abd2eacfc0e15c7ce99853ad8ca52467a5 100644 (file)
--- 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()