1 files changed, 29 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index b5b0c3e61d4..94d10a1aedf 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -6801,6 +6801,14 @@ Value *CodeGenFunction::EmitARMBuiltinExpr(unsigned BuiltinID,
   }
 }
 
+template<typename Integer>
+static Integer GetIntegerConstantValue(const Expr *E, ASTContext &Context) {
+  llvm::APSInt IntVal;
+  bool IsConst = E->isIntegerConstantExpr(IntVal, Context);
+  assert(IsConst && "Sema should have checked this was a constant");
+  return IntVal.getExtValue();
+}
+
 static llvm::Value *SignOrZeroExtend(CGBuilderTy &Builder, llvm::Value *V,
                                      llvm::Type *T, bool Unsigned) {
   // Helper function called by Tablegen-constructed ARM MVE builtin codegen,
@@ -6808,6 +6816,27 @@ static llvm::Value *SignOrZeroExtend(CGBuilderTy &Builder, llvm::Value *V,
   return Unsigned ? Builder.CreateZExt(V, T) : Builder.CreateSExt(V, T);
 }
 
+static llvm::Value *MVEImmediateShr(CGBuilderTy &Builder, llvm::Value *V,
+                                    uint32_t Shift, bool Unsigned) {
+  // MVE helper function for integer shift right. This must handle signed vs
+  // unsigned, and also deal specially with the case where the shift count is
+  // equal to the lane size. In LLVM IR, an LShr with that parameter would be
+  // undefined behavior, but in MVE it's legal, so we must convert it to code
+  // that is not undefined in IR.
+  unsigned LaneBits =
+      V->getType()->getVectorElementType()->getPrimitiveSizeInBits();
+  if (Shift == LaneBits) {
+    // An unsigned shift of the full lane size always generates zero, so we can
+    // simply emit a zero vector. A signed shift of the full lane size does the
+    // same thing as shifting by one bit fewer.
+    if (Unsigned)
+      return llvm::Constant::getNullValue(V->getType());
+    else
+      --Shift;
+  }
+  return Unsigned ? Builder.CreateLShr(V, Shift) : Builder.CreateAShr(V, Shift);
+}
+
 static llvm::Value *ARMMVEVectorSplat(CGBuilderTy &Builder, llvm::Value *V) {
   // MVE-specific helper function for a vector splat, which infers the element
   // count of the output vector by knowing that MVE vectors are all 128 bits