Fix a crash in the legalization of large vectors.

When truncating a result of a vector that is split we need
to use the result of the split vector, and not re-split the dead node.

llvm-svn: 160357

2 files changed, 19 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 75b31f79ade..af90e1d26d5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -592,14 +592,11 @@ SDValue DAGTypeLegalizer::PromoteIntRes_TRUNCATE(SDNode *N) {
     assert(isPowerOf2_32(NumElts) &&
            "Promoted vector type must be a power of two");
 
-    EVT HalfVT = EVT::getVectorVT(*DAG.getContext(), EltVT, NumElts/2);
+    SDValue EOp1, EOp2;
+    GetSplitVector(InOp, EOp1, EOp2);
+
     EVT HalfNVT = EVT::getVectorVT(*DAG.getContext(), NVT.getScalarType(),
                                    NumElts/2);
-
-    SDValue EOp1 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, HalfVT, InOp,
-                               DAG.getIntPtrConstant(0));
-    SDValue EOp2 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, HalfVT, InOp,
-                               DAG.getIntPtrConstant(NumElts/2));
     EOp1 = DAG.getNode(ISD::TRUNCATE, dl, HalfNVT, EOp1);
     EOp2 = DAG.getNode(ISD::TRUNCATE, dl, HalfNVT, EOp2);
 
diff --git a/llvm/test/CodeGen/X86/2012-07-17-vtrunc.ll b/llvm/test/CodeGen/X86/2012-07-17-vtrunc.ll
new file mode 100644
index 00000000000..2de2f97d7d2
--- /dev/null
+++ b/llvm/test/CodeGen/X86/2012-07-17-vtrunc.ll
@@ -0,0 +1,16 @@
+; RUN: llc < %s -march=x86-64 -mcpu=corei7
+
+define void @autogen_SD33189483() {
+BB:
+  br label %CF76
+
+CF76:                                             ; preds = %CF76, %BB
+  %Shuff13 = shufflevector <4 x i64> zeroinitializer, <4 x i64> undef, <4 x i32> zeroinitializer
+  %Tr16 = trunc <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1> to <8 x i1>
+  %E19 = extractelement <8 x i1> %Tr16, i32 2
+  br i1 %E19, label %CF76, label %CF78
+
+CF78:                                             ; preds = %CF78, %CF76
+  %BC = bitcast <4 x i64> %Shuff13 to <4 x double>
+  br label %CF78
+}