Implementation of __builtin_shufflevector, a portable builtin capable of

expressing the full flexibility of the LLVM shufflevector instruction.  
The expected immediate usage is in *mmintrin.h, so that they don't 
depend on the mess of gcc-inherited (and not completely implemented)
shuffle builtins.

llvm-svn: 51113

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 4fb69d045e3..bdd7975fa0c 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -127,6 +127,7 @@ public:
   Value *VisitObjCMessageExpr(ObjCMessageExpr *E);
   Value *VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { return EmitLoadOfLValue(E);}
   Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
+  Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
   Value *VisitMemberExpr(Expr *E)           { return EmitLoadOfLValue(E); }
   Value *VisitExtVectorElementExpr(Expr *E) { return EmitLoadOfLValue(E); }
   Value *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { return EmitLoadOfLValue(E); }
@@ -449,6 +450,17 @@ Value *ScalarExprEmitter::VisitExpr(Expr *E) {
   return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
 }
 
+Value *ScalarExprEmitter::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
+  llvm::SmallVector<llvm::Constant*, 32> indices;
+  for (unsigned i = 2; i < E->getNumSubExprs(); i++) {
+    indices.push_back(cast<llvm::Constant>(CGF.EmitScalarExpr(E->getExpr(i))));
+  }
+  Value* V1 = CGF.EmitScalarExpr(E->getExpr(0));
+  Value* V2 = CGF.EmitScalarExpr(E->getExpr(1));
+  Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
+  return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
+}
+
 Value *ScalarExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
   // Only the lookup mechanism and first two arguments of the method
   // implementation vary between runtimes.  We can get the receiver and