From 157efd84abf812c1689ba6a9ecb4da2b87dde756 Mon Sep 17 00:00:00 2001
From: Serguei Katkov <serguei.katkov@azul.com>
Date: Tue, 12 Jan 2021 11:52:48 +0700
Subject: [PATCH] [Statepoint Lowering] Add an option to allow use gc values in
 regs for landing pad

Default value is not changed, so it is NFC actually.

The option allows to use gc values on registers in landing pads.

Reviewers: reames, dantrushin
Reviewed By: reames, dantrushin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D94469
---
 .../SelectionDAG/StatepointLowering.cpp       | 21 ++++++++++++-------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
index 5638feaf1540..0172646c22ec 100644
--- a/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -64,6 +64,10 @@ cl::opt<bool> UseRegistersForDeoptValues(
     "use-registers-for-deopt-values", cl::Hidden, cl::init(false),
     cl::desc("Allow using registers for non pointer deopt args"));
 
+cl::opt<bool> UseRegistersForGCPointersInLandingPad(
+    "use-registers-for-gc-values-in-landing-pad", cl::Hidden, cl::init(false),
+    cl::desc("Allow using registers for gc pointer in landing pad"));
+
 cl::opt<unsigned> MaxRegistersForGCPointers(
     "max-registers-for-gc-values", cl::Hidden, cl::init(0),
     cl::desc("Max number of VRegs allowed to pass GC pointer meta args in"));
@@ -549,14 +553,15 @@ lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops,
   // Pointers used on exceptional path of invoke statepoint.
   // We cannot assing them to VRegs.
   SmallSet<SDValue, 8> LPadPointers;
-  if (auto *StInvoke = dyn_cast_or_null<InvokeInst>(SI.StatepointInstr)) {
-    LandingPadInst *LPI = StInvoke->getLandingPadInst();
-    for (auto *Relocate : SI.GCRelocates)
-      if (Relocate->getOperand(0) == LPI) {
-        LPadPointers.insert(Builder.getValue(Relocate->getBasePtr()));
-        LPadPointers.insert(Builder.getValue(Relocate->getDerivedPtr()));
-      }
-  }
+  if (!UseRegistersForGCPointersInLandingPad)
+    if (auto *StInvoke = dyn_cast_or_null<InvokeInst>(SI.StatepointInstr)) {
+      LandingPadInst *LPI = StInvoke->getLandingPadInst();
+      for (auto *Relocate : SI.GCRelocates)
+        if (Relocate->getOperand(0) == LPI) {
+          LPadPointers.insert(Builder.getValue(Relocate->getBasePtr()));
+          LPadPointers.insert(Builder.getValue(Relocate->getDerivedPtr()));
+        }
+    }
 
   LLVM_DEBUG(dbgs() << "Deciding how to lower GC Pointers:\n");