[llvm] r277993 - [X86][SSE] Assert if the shuffle mask indices are not -1 or within a valid input range

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Mon Aug  8 06:07:34 2016
New Revision: 277993

URL: http://llvm.org/viewvc/llvm-project?rev=277993&view=rev
Log:
[X86][SSE] Assert if the shuffle mask indices are not -1 or within a valid input range

As discussed in post-review rL277959

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=277993&r1=277992&r2=277993&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Aug  8 06:07:34 2016
@@ -12287,14 +12287,11 @@ static SDValue lowerVectorShuffle(SDValu
         return DAG.getVectorShuffle(VT, DL, V1, V2, NewMask);
       }
 
-  // Ensure that undefined mask elements only use SM_SentinelUndef.
-  if (llvm::any_of(Mask, [](int M) { return M < SM_SentinelUndef; })) {
-    SmallVector<int, 8> NewMask(Mask.begin(), Mask.end());
-    for (int &M : NewMask)
-      if (M < SM_SentinelUndef)
-        M = SM_SentinelUndef;
-    return DAG.getVectorShuffle(VT, DL, V1, V2, NewMask);
-  }
+  // Check for illegal shuffle mask element index values.
+  int MaskUpperLimit = Mask.size() * (V2IsUndef ? 1 : 2); (void)MaskUpperLimit;
+  assert(llvm::all_of(Mask,
+                      [&](int M) { return -1 <= M && M < MaskUpperLimit; }) &&
+         "Out of bounds shuffle index");
 
   // We actually see shuffles that are entirely re-arrangements of a set of
   // zero inputs. This mostly happens while decomposing complex shuffles into