[PATCH] D66278: [RISCV] Enable tail call opt for variadic function

[Jim Lin via Phabricator via llvm-commits]

Jim created this revision.
Jim added reviewers: mgrang, asb, lenary, lewis-revill.
Herald added subscribers: llvm-commits, s.egerton, benna, psnobl, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, MaskRay, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, apazos, simoncook, johnrusso, rbar.
Herald added a project: LLVM.

Tail call opt can treat variadic function call the same as normal function call


Repository:
  rL LLVM

https://reviews.llvm.org/D66278

Files:
  lib/Target/RISCV/RISCVISelLowering.cpp
  test/CodeGen/RISCV/tail-calls.ll


Index: test/CodeGen/RISCV/tail-calls.ll
===================================================================
--- test/CodeGen/RISCV/tail-calls.ll
+++ test/CodeGen/RISCV/tail-calls.ll
@@ -47,17 +47,6 @@
   ret void
 }
 
-; Do not tail call optimize functions with varargs.
-declare i32 @callee_varargs(i32, ...)
-define void @caller_varargs(i32 %a, i32 %b) nounwind {
-; CHECK-LABEL: caller_varargs
-; CHECK-NOT: tail callee_varargs
-; CHECK: call callee_varargs
-entry:
-  %call = tail call i32 (i32, ...) @callee_varargs(i32 %a, i32 %b, i32 %b, i32 %a)
-  ret void
-}
-
 ; Do not tail call optimize if stack is used to pass parameters.
 declare i32 @callee_args(i32 %a, i32 %b, i32 %c, i32 %dd, i32 %e, i32 %ff, i32 %g, i32 %h, i32 %i, i32 %j, i32 %k, i32 %l, i32 %m, i32 %n)
 define i32 @caller_args(i32 %a, i32 %b, i32 %c, i32 %dd, i32 %e, i32 %ff, i32 %g, i32 %h, i32 %i, i32 %j, i32 %k, i32 %l, i32 %m, i32 %n) nounwind {
Index: lib/Target/RISCV/RISCVISelLowering.cpp
===================================================================
--- lib/Target/RISCV/RISCVISelLowering.cpp
+++ lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1946,7 +1946,6 @@
 
   auto &Callee = CLI.Callee;
   auto CalleeCC = CLI.CallConv;
-  auto IsVarArg = CLI.IsVarArg;
   auto &Outs = CLI.Outs;
   auto &Caller = MF.getFunction();
   auto CallerCC = Caller.getCallingConv();
@@ -1963,10 +1962,6 @@
   if (Caller.hasFnAttribute("interrupt"))
     return false;
 
-  // Do not tail call opt functions with varargs.
-  if (IsVarArg)
-    return false;
-
   // Do not tail call opt if the stack is used to pass parameters.
   if (CCInfo.getNextStackOffset() != 0)
     return false;


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