[llvm-commits] [llvm] r142370 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/ARM/vector-DAGCombine.ll

[Bob Wilson]

Author: bwilson
Date: Tue Oct 18 12:34:47 2011
New Revision: 142370

URL: http://llvm.org/viewvc/llvm-project?rev=142370&view=rev
Log:
Fix a DAG combiner assertion failure when constant folding BUILD_VECTORS.

svn r139159 caused SelectionDAG::getConstant() to promote BUILD_VECTOR operands
with illegal types, even before type legalization.  For this testcase, that led
to one BUILD_VECTOR with i16 operands and another with promoted i32 operands,
which triggered the assertion.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/ARM/vector-DAGCombine.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=142370&r1=142369&r2=142370&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue Oct 18 12:34:47 2011
@@ -7261,8 +7261,19 @@
       }
 
       EVT VT = LHSOp.getValueType();
-      assert(RHSOp.getValueType() == VT &&
-             "SimplifyVBinOp with different BUILD_VECTOR element types");
+      EVT RVT = RHSOp.getValueType();
+      if (RVT != VT) {
+        // Integer BUILD_VECTOR operands may have types larger than the element
+        // size (e.g., when the element type is not legal).  Prior to type
+        // legalization, the types may not match between the two BUILD_VECTORS.
+        // Truncate one of the operands to make them match.
+        if (RVT.getSizeInBits() > VT.getSizeInBits()) {
+          RHSOp = DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, RHSOp);
+        } else {
+          LHSOp = DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), RVT, LHSOp);
+          VT = RVT;
+        }
+      }
       SDValue FoldOp = DAG.getNode(N->getOpcode(), LHS.getDebugLoc(), VT,
                                    LHSOp, RHSOp);
       if (FoldOp.getOpcode() != ISD::UNDEF &&

Modified: llvm/trunk/test/CodeGen/ARM/vector-DAGCombine.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/vector-DAGCombine.ll?rev=142370&r1=142369&r2=142370&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/vector-DAGCombine.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/vector-DAGCombine.ll Tue Oct 18 12:34:47 2011
@@ -123,3 +123,13 @@
   ret void
 }
 
+; The following test was hitting an assertion in the DAG combiner when
+; constant folding the multiply because the "sext undef" was translated to
+; a BUILD_VECTOR with i32 0 operands, which did not match the i16 operands
+; of the other BUILD_VECTOR.
+define i16 @foldBuildVectors() {
+  %1 = sext <8 x i8> undef to <8 x i16>
+  %2 = mul <8 x i16> %1, <i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255>
+  %3 = extractelement <8 x i16> %2, i32 0
+  ret i16 %3
+}