diff options
| -rw-r--r-- | lib/Target/PowerPC/PPCISelLowering.cpp | 15 | ||||
| -rw-r--r-- | test/CodeGen/PowerPC/duplicate-returns-for-tailcall.ll | 6 |
2 files changed, 13 insertions, 8 deletions
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp index 3fe9fe73499..f885127e6aa 100644 --- a/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/lib/Target/PowerPC/PPCISelLowering.cpp @@ -4397,13 +4397,18 @@ hasSameArgumentList(const Function *CallerFn, ImmutableCallSite CS) { static bool areCallingConvEligibleForTCO_64SVR4(CallingConv::ID CallerCC, CallingConv::ID CalleeCC) { - // Tail or Sibling call optimization (TCO/SCO) needs callee and caller to - // have the same calling convention. - if (CallerCC != CalleeCC) + // tail calls are possible with fastcc and ccc. + auto isTailCallableCC = [] (CallingConv::ID CC){ + return CC == CallingConv::C || CC == CallingConv::Fast; + }; + if (!isTailCallableCC(CallerCC) || !isTailCallableCC(CalleeCC)) return false; - // Tail or Sibling calls can be done with fastcc/ccc. - return (CallerCC == CallingConv::Fast || CallerCC == CallingConv::C); + // We can safely tail call both fastcc and ccc callees from a c calling + // convention caller. If the caller is fastcc, we may have less stack space + // then a non-fastcc caller with the same signature so disable tail-calls in + // that case. + return CallerCC == CallingConv::C || CallerCC == CalleeCC; } bool diff --git a/test/CodeGen/PowerPC/duplicate-returns-for-tailcall.ll b/test/CodeGen/PowerPC/duplicate-returns-for-tailcall.ll index 520efd8106f..9c0e77dafde 100644 --- a/test/CodeGen/PowerPC/duplicate-returns-for-tailcall.ll +++ b/test/CodeGen/PowerPC/duplicate-returns-for-tailcall.ll @@ -42,10 +42,10 @@ if.end4: ; preds = %if.end if.then6: ; preds = %if.end4 %call7 = tail call fastcc signext i32 @call3(i32 signext %a, i32 signext %b, i32 signext %c) br label %return -; No duplication here because the calling convention mismatch means we won't tail-call +; tail calling a fastcc function from a ccc function is supported. ; CHECK_LABEL: if.then13: -; CHECK: tail call fastcc signext i32 @call3 -; CHECK-NEXT: br +; CHECK: %[[T2:[a-zA-Z0-9]+]] = tail call fastcc signext i32 @call3 +; CHECK-NEXT: ret i32 %[[T2]] return: ; preds = %if.end4, %if.then6, %if.then2, %if.then %retval.0 = phi i32 [ %call, %if.then ], [ %call3, %if.then2 ], [ %call7, %if.then6 ], [ %c, %if.end4 ] |