[llvm-commits] [llvm] r60829 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/extractelement-shuffle.ll

[Mon P Wang]

Author: wangmp
Date: Tue Dec  9 21:59:02 2008
New Revision: 60829

URL: http://llvm.org/viewvc/llvm-project?rev=60829&view=rev
Log:
Fixed a bug when trying to optimize a extract vector element of a
bit convert that changes the number of elements of a shuffle.

Added:
    llvm/trunk/test/CodeGen/X86/extractelement-shuffle.ll
Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=60829&r1=60828&r2=60829&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue Dec  9 21:59:02 2008
@@ -4874,7 +4874,8 @@
     MVT LVT = EVT;
     if (InVec.getOpcode() == ISD::BIT_CONVERT) {
       MVT BCVT = InVec.getOperand(0).getValueType();
-      if (!BCVT.isVector() || EVT.bitsGT(BCVT.getVectorElementType()))
+      if (!BCVT.isVector() || EVT.bitsGT(BCVT.getVectorElementType()) ||
+          VT.getVectorNumElements() != BCVT.getVectorNumElements())
         return SDValue();
       InVec = InVec.getOperand(0);
       EVT = BCVT.getVectorElementType();

Added: llvm/trunk/test/CodeGen/X86/extractelement-shuffle.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/extractelement-shuffle.ll?rev=60829&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/extractelement-shuffle.ll (added)
+++ llvm/trunk/test/CodeGen/X86/extractelement-shuffle.ll Tue Dec  9 21:59:02 2008
@@ -0,0 +1,13 @@
+; RUN: llvm-as < %s | llc
+
+; Examples that exhibits a bug in DAGCombine.  The case is triggered by the
+; following program.  The bug is DAGCombine assumes that the bit convert
+; preserves the number of elements so the optimization code tries to read
+; through the 3rd mask element, which doesn't exist.
+define i32 @update(<2 x i64> %val1, <2 x i64> %val2) nounwind readnone {
+entry:
+	%shuf = shufflevector <2 x i64> %val1, <2 x i64> %val2, <2 x i32> <i32 0, i32 3>;
+	%bit  = bitcast <2 x i64> %shuf to <4 x i32>;
+	%res =  extractelement <4 x i32> %bit, i32 3;
+	ret i32 %res;
+}
\ No newline at end of file