[PATCH] D37406: [TailCall] Allow llvm.memcpy/memset/memmove to be tail calls when parent function return the intrinsics's first argument

[Wei Mi via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL312641: [TailCall] Allow llvm.memcpy/memset/memmove to be tail calls when parent (authored by wmi).

Changed prior to commit:
  https://reviews.llvm.org/D37406?vs=113625&id=114018#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D37406

Files:
  llvm/trunk/lib/CodeGen/Analysis.cpp
  llvm/trunk/test/CodeGen/X86/tailcall-mem-intrinsics.ll


Index: llvm/trunk/lib/CodeGen/Analysis.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/Analysis.cpp
+++ llvm/trunk/lib/CodeGen/Analysis.cpp
@@ -565,6 +565,17 @@
     return false;
 
   const Value *RetVal = Ret->getOperand(0), *CallVal = I;
+  // Intrinsic like llvm.memcpy has no return value, but will return the
+  // first argument if it is expanded as libcall.
+  const CallInst *Call = cast<CallInst>(I);
+  if (Function *F = Call->getCalledFunction()) {
+    Intrinsic::ID IID = F->getIntrinsicID();
+    if ((IID == Intrinsic::memcpy || IID == Intrinsic::memmove ||
+         IID == Intrinsic::memset) &&
+        RetVal == Call->getArgOperand(0))
+      return true;
+  }
+
   SmallVector<unsigned, 4> RetPath, CallPath;
   SmallVector<CompositeType *, 4> RetSubTypes, CallSubTypes;
 
Index: llvm/trunk/test/CodeGen/X86/tailcall-mem-intrinsics.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/tailcall-mem-intrinsics.ll
+++ llvm/trunk/test/CodeGen/X86/tailcall-mem-intrinsics.ll
@@ -24,6 +24,30 @@
   ret void
 }
 
+; CHECK-LABEL: tail_memcpy_ret
+; CHECK: jmp memcpy
+define i8* @tail_memcpy_ret(i8* nocapture %p, i8* nocapture readonly %q, i32 %n) #0 {
+entry:
+  tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %p, i8* %q, i32 %n, i32 1, i1 false)
+  ret i8* %p
+}
+
+; CHECK-LABEL: tail_memmove_ret
+; CHECK: jmp memmove
+define i8* @tail_memmove_ret(i8* nocapture %p, i8* nocapture readonly %q, i32 %n) #0 {
+entry:
+  tail call void @llvm.memmove.p0i8.p0i8.i32(i8* %p, i8* %q, i32 %n, i32 1, i1 false)
+  ret i8* %p
+}
+
+; CHECK-LABEL: tail_memset_ret
+; CHECK: jmp memset
+define i8* @tail_memset_ret(i8* nocapture %p, i8 %c, i32 %n) #0 {
+entry:
+  tail call void @llvm.memset.p0i8.i32(i8* %p, i8 %c, i32 %n, i32 1, i1 false)
+  ret i8* %p
+}
+
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly, i32, i32, i1) #0
 declare void @llvm.memmove.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly, i32, i32, i1) #0
 declare void @llvm.memset.p0i8.i32(i8* nocapture, i8, i32, i32, i1) #0


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