Allow SelectionDAG to create EXTRACT_VECTOR_ELT nodes with

non-constant indices. Only a few of the peephole checks require
a constant index.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54764 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 11 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f8c11456d9..144dc6e198 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2302,15 +2302,14 @@ SDValue SelectionDAG::getNode(unsigned Opcode, MVT VT,
     break;
   }
   case ISD::EXTRACT_VECTOR_ELT:
-    assert(N2C && "Bad EXTRACT_VECTOR_ELT!");
-
     // EXTRACT_VECTOR_ELT of an UNDEF is an UNDEF.
     if (N1.getOpcode() == ISD::UNDEF)
       return getNode(ISD::UNDEF, VT);
       
     // EXTRACT_VECTOR_ELT of CONCAT_VECTORS is often formed while lowering is
     // expanding copies of large vectors from registers.
-    if (N1.getOpcode() == ISD::CONCAT_VECTORS &&
+    if (N2C &&
+        N1.getOpcode() == ISD::CONCAT_VECTORS &&
         N1.getNumOperands() > 0) {
       unsigned Factor =
         N1.getOperand(0).getValueType().getVectorNumElements();
@@ -2321,18 +2320,17 @@ SDValue SelectionDAG::getNode(unsigned Opcode, MVT VT,
 
     // EXTRACT_VECTOR_ELT of BUILD_VECTOR is often formed while lowering is
     // expanding large vector constants.
-    if (N1.getOpcode() == ISD::BUILD_VECTOR)
+    if (N2C && N1.getOpcode() == ISD::BUILD_VECTOR)
       return N1.getOperand(N2C->getValue());
       
     // EXTRACT_VECTOR_ELT of INSERT_VECTOR_ELT is often formed when vector
     // operations are lowered to scalars.
-    if (N1.getOpcode() == ISD::INSERT_VECTOR_ELT)
-      if (ConstantSDNode *IEC = dyn_cast<ConstantSDNode>(N1.getOperand(2))) {
-        if (IEC == N2C)
-          return N1.getOperand(1);
-        else
-          return getNode(ISD::EXTRACT_VECTOR_ELT, VT, N1.getOperand(0), N2);
-      }
+    if (N1.getOpcode() == ISD::INSERT_VECTOR_ELT) {
+      if (N1.getOperand(2) == N2)
+        return N1.getOperand(1);
+      else
+        return getNode(ISD::EXTRACT_VECTOR_ELT, VT, N1.getOperand(0), N2);
+    }
     break;
   case ISD::EXTRACT_ELEMENT:
     assert(N2C && (unsigned)N2C->getValue() < 2 && "Bad EXTRACT_ELEMENT!");
diff --git a/test/CodeGen/X86/vector-variable-idx.ll b/test/CodeGen/X86/vector-variable-idx.ll
new file mode 100644
index 0000000000..82927e9698
--- /dev/null
+++ b/test/CodeGen/X86/vector-variable-idx.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-as < %s | llc -march=x86-64 | grep movss | count 2
+; PR2676
+
+define float @foo(<4 x float> %p, i32 %t) {
+  %z = extractelement <4 x float> %p, i32 %t
+  ret float %z
+}
+define <4 x float> @bar(<4 x float> %p, float %f, i32 %t) {
+  %z = insertelement <4 x float> %p, float %f, i32 %t
+  ret <4 x float> %z
+}