[Verifier] Diagnose when unwinding out of cycles of blocks

Generally speaking, this can only happen with unreachable code.
However, neglecting to check for this condition would lead us to loop
forever.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262284 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index 8367a27..bea9b34 100644 (file)
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -3064,6 +3064,7 @@ void Verifier::visitEHPadPredecessors(Instruction &I) {
     }
 
     // The edge may exit from zero or more nested pads.
+    SmallSet<Value *, 8> Seen;
     for (;; FromPad = getParentPad(FromPad)) {
       Assert(FromPad != ToPad,
              "EH pad cannot handle exceptions raised within it", FromPad, TI);
@@ -3073,6 +3074,8 @@ void Verifier::visitEHPadPredecessors(Instruction &I) {
       }
       Assert(!isa<ConstantTokenNone>(FromPad),
              "A single unwind edge may only enter one EH pad", TI);
+      Assert(Seen.insert(FromPad).second,
+             "EH pad jumps through a cycle of pads", FromPad);
     }
   }
 }
@@ -3171,7 +3174,7 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
   User *FirstUser = nullptr;
   Value *FirstUnwindPad = nullptr;
   SmallVector<FuncletPadInst *, 8> Worklist({&FPI});
-  std::set<FuncletPadInst *> Seen;
+  SmallSet<FuncletPadInst *, 8> Seen;
 
   while (!Worklist.empty()) {
     FuncletPadInst *CurrentPad = Worklist.pop_back_val();

diff --git a/test/Verifier/invalid-eh.ll b/test/Verifier/invalid-eh.ll
index f94e3a6..e631715 100644 (file)
--- a/test/Verifier/invalid-eh.ll
+++ b/test/Verifier/invalid-eh.ll
@@ -22,6 +22,7 @@
 ; RUN: sed -e s/.T22:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK22 %s
 ; RUN: sed -e s/.T23:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK23 %s
 ; RUN: sed -e s/.T24:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK24 %s
+; RUN: sed -e s/.T25:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK25 %s
 
 declare void @g()
 
@@ -420,3 +421,21 @@ declare void @g()
 ;T24: exit:
 ;T24:   unreachable
 ;T24: }
+
+;T25: define void @f() personality void ()* @g {
+;T25: entry:
+;T25:   unreachable
+;T25:
+;T25: catch.dispatch:
+;T25:   %cs = catchswitch within %cp2 [label %catch] unwind label %ehcleanup
+;T25:   ; CHECK25: EH pad jumps through a cycle of pads
+;T25:   ; CHECK25:   %cs = catchswitch within %cp2 [label %catch] unwind label %ehcleanup
+;T25:
+;T25: catch:
+;T25:   %cp2 = catchpad within %cs [i8* null, i32 64, i8* null]
+;T25:   unreachable
+;T25:
+;T25: ehcleanup:
+;T25:   %cp3 = cleanuppad within none []
+;T25:   cleanupret from %cp3 unwind to caller
+;T25: }