[llvm] [CodeGen][SDAG] Track returntwice in lowering info (PR #92640)

[via llvm-commits]

https://github.com/aengelke created https://github.com/llvm/llvm-project/pull/92640

This saves an extra iteration over the all instructions of the function.

>From 6ba389a61a89c2617473c661b6b823110521f803 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <engelke at in.tum.de>
Date: Sat, 18 May 2024 10:55:34 +0200
Subject: [PATCH] [CodeGen][SDAG] Track returntwice in lowering info

This saves an extra iteration over the all instructions of the function.
---
 llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp | 4 ++++
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp     | 3 ---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 8fb6b11b8805c..6ea17b4386cda 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -214,6 +214,10 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
           if (CI->isMustTailCall() && Fn->isVarArg())
             MF->getFrameInfo().setHasMustTailInVarArgFunc(true);
         }
+
+        // Determine if there is a call to setjmp in the machine function.
+        if (Call->hasFnAttr(Attribute::ReturnsTwice))
+          MF->setExposesReturnsTwice(true);
       }
 
       // Mark values used outside their block as exported, by allocating
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index b5694c955b8c8..8addaf1ae3e54 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -680,9 +680,6 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
     }
   }
 
-  // Determine if there is a call to setjmp in the machine function.
-  MF->setExposesReturnsTwice(Fn.callsFunctionThatReturnsTwice());
-
   // Determine if floating point is used for msvc
   computeUsesMSVCFloatingPoint(TM.getTargetTriple(), Fn, MF->getMMI());