[PATCH] D59078: memcpy is not tailcalled

[Ramakota Reddy via Phabricator via llvm-commits]

ramred01 created this revision.
ramred01 added reviewers: wmi, mkuper.

In library routines like memcpy, memmove, memset, etc., the first argument that is passed is returned as the return value.  LLVM was not able to tailcall these functions.  This patch fixes the issue.


https://reviews.llvm.org/D59078

Files:
  lib/CodeGen/Analysis.cpp


Index: lib/CodeGen/Analysis.cpp
===================================================================
--- lib/CodeGen/Analysis.cpp
+++ lib/CodeGen/Analysis.cpp
@@ -590,6 +590,7 @@
   // argument. On other platforms like arm-none-eabi, memcpy may be
   // expanded as library call without return value, like __aeabi_memcpy.
   const CallInst *Call = cast<CallInst>(I);
+  auto *BitCastIn = dyn_cast<BitCastInst>(Call->getArgOperand(0));
   if (Function *F = Call->getCalledFunction()) {
     Intrinsic::ID IID = F->getIntrinsicID();
     if (((IID == Intrinsic::memcpy &&
@@ -598,7 +599,10 @@
           TLI.getLibcallName(RTLIB::MEMMOVE) == StringRef("memmove")) ||
          (IID == Intrinsic::memset &&
           TLI.getLibcallName(RTLIB::MEMSET) == StringRef("memset"))) &&
-        RetVal == Call->getArgOperand(0))
+        (RetVal == Call->getArgOperand(0) || 
+         (BitCastIn && RetVal == BitCastIn->getOperand(0) && 
+          Call->getArgOperand(0)->getType()->isPointerTy() &&
+          BitCastIn->getOperand(0)->getType()->isPointerTy())))
       return true;
   }
 


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