[llvm-commits] [llvm] r128782 - in /llvm/trunk: include/llvm/Transforms/Utils/Local.h lib/Transforms/Utils/Local.cpp test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll

[Eli Friedman]

Author: efriedma
Date: Sat Apr  2 17:45:17 2011
New Revision: 128782

URL: http://llvm.org/viewvc/llvm-project?rev=128782&view=rev
Log:
PR9446: RecursivelyDeleteTriviallyDeadInstructions can delete the instruction
after the given instruction; make sure to handle that case correctly.
(It's difficult to trigger; the included testcase involves a dead 
block, but I don't think that's a requirement.) 

While I'm here, get rid of the unnecessary warning about
SimplifyInstructionsInBlock, since it should work correctly as far as I know.


Added:
    llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll
Modified:
    llvm/trunk/include/llvm/Transforms/Utils/Local.h
    llvm/trunk/lib/Transforms/Utils/Local.cpp

Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=128782&r1=128781&r2=128782&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Sat Apr  2 17:45:17 2011
@@ -74,10 +74,6 @@
 ///
 /// This returns true if it changed the code, note that it can delete
 /// instructions in other blocks as well in this block.
-///
-/// WARNING: Do not use this function on unreachable blocks, as recursive
-/// simplification is not able to handle corner-case scenarios that can
-/// arise in them.
 bool SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD = 0);
     
 //===----------------------------------------------------------------------===//

Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=128782&r1=128781&r2=128782&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Sat Apr  2 17:45:17 2011
@@ -332,8 +332,11 @@
         BI = BB->begin();
       continue;
     }
-    
+
+    WeakVH BIHandle(BI);
     MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst);
+    if (BIHandle != BI)
+      BI = BB->begin();
   }
   return MadeChange;
 }

Added: llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll?rev=128782&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll (added)
+++ llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll Sat Apr  2 17:45:17 2011
@@ -0,0 +1,32 @@
+; RUN: opt < %s -jump-threading
+; PR9446
+; Just check that it doesn't crash
+
+define void @int327() nounwind {
+entry:
+  unreachable
+
+for.cond:                                         ; preds = %for.cond4
+  %tobool3 = icmp eq i8 undef, 0
+  br i1 %tobool3, label %for.cond23, label %for.cond4
+
+for.cond4:                                        ; preds = %for.cond
+  br label %for.cond
+
+for.cond23:                                       ; preds = %for.body28, %for.cond23, %for.cond
+  %conv321 = phi i32 [ %conv32, %for.body28 ], [ 0, %for.cond ], [ %conv321, %for.cond23 ]
+  %l_266.0 = phi i32 [ %phitmp, %for.body28 ], [ 0, %for.cond ], [ 0, %for.cond23 ]
+  %cmp26 = icmp eq i32 %l_266.0, 0
+  br i1 %cmp26, label %for.body28, label %for.cond23
+
+for.body28:                                       ; preds = %for.cond23
+  %and = and i32 %conv321, 1
+  %conv32 = zext i8 undef to i32
+  %add = add nsw i32 %l_266.0, 1
+  %phitmp = and i32 %add, 255
+  br label %for.cond23
+
+if.end43:                                         ; No predecessors!
+  ret void
+}
+