[llvm] r262284 - [Verifier] Diagnose when unwinding out of cycles of blocks

[David Majnemer via llvm-commits]

Author: majnemer
Date: Mon Feb 29 19:19:05 2016
New Revision: 262284

URL: http://llvm.org/viewvc/llvm-project?rev=262284&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/IR/Verifier.cpp
    llvm/trunk/test/Verifier/invalid-eh.ll

Modified: llvm/trunk/lib/IR/Verifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Verifier.cpp?rev=262284&r1=262283&r2=262284&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Verifier.cpp (original)
+++ llvm/trunk/lib/IR/Verifier.cpp Mon Feb 29 19:19:05 2016
@@ -3064,6 +3064,7 @@ void Verifier::visitEHPadPredecessors(In
     }
 
     // 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(In
       }
       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(Funcl
   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();

Modified: llvm/trunk/test/Verifier/invalid-eh.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Verifier/invalid-eh.ll?rev=262284&r1=262283&r2=262284&view=diff
==============================================================================
--- llvm/trunk/test/Verifier/invalid-eh.ll (original)
+++ llvm/trunk/test/Verifier/invalid-eh.ll Mon Feb 29 19:19:05 2016
@@ -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: }