Hexagon: Add runtime libcall entries for volatile memcpy call

This pass currently doesn't have TargetLoweringInfo, but technically
it should verify the call is available from a future RuntimeLibcallsInfo
analysis.

Author: arsenm

llvm/include/llvm/IR/RuntimeLibcalls.td

@@ -446,6 +446,7 @@ def AEABI_MEMCLR8 : RuntimeLibcall;
 
 // Hexagon calls
 def HEXAGON_MEMCPY_LIKELY_ALIGNED_MIN32BYTES_MULT8BYTES : RuntimeLibcall;
+def HEXAGON_VOLATILE_MEMCPY : RuntimeLibcall;
 
 // XCore calls
 def MEMCPY_ALIGN_4 : RuntimeLibcall;
@@ -1875,6 +1876,8 @@ def __hexagon_fast2_sqrtdf2 : RuntimeLibcallImpl<FAST_SQRT_F64>;
 
 def __hexagon_memcpy_likely_aligned_min32bytes_mult8bytes
     : RuntimeLibcallImpl<HEXAGON_MEMCPY_LIKELY_ALIGNED_MIN32BYTES_MULT8BYTES>;
+
+def hexagon_memcpy_forward_vp4cp4n2 : RuntimeLibcallImpl<HEXAGON_VOLATILE_MEMCPY>;
 }
 
 def isHexagon : RuntimeLibcallPredicate<"TT.getArch() == Triple::hexagon">;

llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp

@@ -42,6 +42,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/RuntimeLibcalls.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
@@ -2246,6 +2247,11 @@ bool HexagonLoopIdiomRecognize::processCopyingStore(Loop *CurLoop,
       Type *PtrTy = PointerType::get(Ctx, 0);
       Type *VoidTy = Type::getVoidTy(Ctx);
       Module *M = Func->getParent();
+
+      // FIXME: This should check if the call is supported
+      StringRef HexagonVolatileMemcpyName =
+          RuntimeLibcallsInfo::getLibcallImplName(
+              RTLIB::impl_hexagon_memcpy_forward_vp4cp4n2);
       FunctionCallee Fn = M->getOrInsertFunction(
           HexagonVolatileMemcpyName, VoidTy, PtrTy, PtrTy, Int32Ty);