[llvm] r294982 - swiftcc: Don't emit tail calls from callers with swifterror parameters

[Arnold Schwaighofer via llvm-commits]

Author: arnolds
Date: Mon Feb 13 13:58:28 2017
New Revision: 294982

URL: http://llvm.org/viewvc/llvm-project?rev=294982&view=rev
Log:
swiftcc: Don't emit tail calls from callers with swifterror parameters

Backends don't support this yet. They would have to move to the swifterror
register before the tail call to make sure it is live-in to the call.

rdar://30495920

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
    llvm/trunk/test/CodeGen/AArch64/swifterror.ll
    llvm/trunk/test/CodeGen/ARM/swifterror.ll
    llvm/trunk/test/CodeGen/X86/swifterror.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=294982&r1=294981&r2=294982&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Mon Feb 13 13:58:28 2017
@@ -5916,6 +5916,15 @@ void SelectionDAGBuilder::LowerCallTo(Im
 
   const Value *SwiftErrorVal = nullptr;
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+
+  // We can't tail call inside a function with a swifterror argument. Lowering
+  // does not support this yet. It would have to move into the swifterror
+  // register before the call.
+  auto *Caller = CS.getInstruction()->getParent()->getParent();
+  if (TLI.supportSwiftError() &&
+      Caller->getAttributes().hasAttrSomewhere(Attribute::SwiftError))
+    isTailCall = false;
+
   for (ImmutableCallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
        i != e; ++i) {
     const Value *V = *i;

Modified: llvm/trunk/test/CodeGen/AArch64/swifterror.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/swifterror.ll?rev=294982&r1=294981&r2=294982&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/swifterror.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/swifterror.ll Mon Feb 13 13:58:28 2017
@@ -583,3 +583,17 @@ define swiftcc { i64, i64, i64, i64, i64
 }
 
 declare swiftcc { i64, i64, i64, i64, i64, i64, i64, i64 } @params_and_return_in_reg2(i64, i64, i64, i64, i64, i64, i64, i64, i8* swiftself, %swift_error** nocapture swifterror %err)
+
+declare void @acallee(i8*)
+
+; Make sure we don't tail call if the caller returns a swifterror value. We
+; would have to move into the swifterror register before the tail call.
+; CHECK-APPLE: tailcall_from_swifterror:
+; CHECK-APPLE-NOT: b _acallee
+; CHECK-APPLE: bl _acallee
+
+define swiftcc void @tailcall_from_swifterror(%swift_error** swifterror %error_ptr_ref) {
+entry:
+  tail call void @acallee(i8* null)
+  ret void
+}

Modified: llvm/trunk/test/CodeGen/ARM/swifterror.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/swifterror.ll?rev=294982&r1=294981&r2=294982&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/swifterror.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/swifterror.ll Mon Feb 13 13:58:28 2017
@@ -513,3 +513,18 @@ define swiftcc { i32, i32, i32, i32} @pa
 }
 
 declare swiftcc { i32, i32, i32, i32 } @params_and_return_in_reg2(i32, i32, i32, i32, i8* swiftself, %swift_error** nocapture swifterror %err)
+
+
+declare void @acallee(i8*)
+
+; Make sure we don't tail call if the caller returns a swifterror value. We
+; would have to move into the swifterror register before the tail call.
+; CHECK-APPLE: tailcall_from_swifterror:
+; CHECK-APPLE-NOT: b _acallee
+; CHECK-APPLE: bl _acallee
+
+define swiftcc void @tailcall_from_swifterror(%swift_error** swifterror %error_ptr_ref) {
+entry:
+  tail call void @acallee(i8* null)
+  ret void
+}

Modified: llvm/trunk/test/CodeGen/X86/swifterror.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/swifterror.ll?rev=294982&r1=294981&r2=294982&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/swifterror.ll (original)
+++ llvm/trunk/test/CodeGen/X86/swifterror.ll Mon Feb 13 13:58:28 2017
@@ -670,3 +670,18 @@ define swiftcc { i64, i64, i64, i64} @pa
 }
 
 declare swiftcc { i64, i64, i64, i64 } @params_and_return_in_reg2(i64, i64, i64, i64, i64, i64, i8* swiftself, %swift_error** nocapture swifterror %err)
+
+
+declare void @acallee(i8*)
+
+; Make sure we don't tail call if the caller returns a swifterror value. We
+; would have to move into the swifterror register before the tail call.
+; CHECK-APPLE: tailcall_from_swifterror:
+; CHECK-APPLE-NOT: jmp _acallee
+; CHECK-APPLE: callq _acallee
+
+define swiftcc void @tailcall_from_swifterror(%swift_error** swifterror %error_ptr_ref) {
+entry:
+  tail call void @acallee(i8* null)
+  ret void
+}