From b7e3759e177ef2ddc5adaf7951bb6fba1e5533fe Mon Sep 17 00:00:00 2001
From: Serguei Katkov <serguei.katkov@azul.com>
Date: Tue, 7 Apr 2020 11:04:19 +0700
Subject: [PATCH] [DAG] Consolidate require spill slot logic in lambda. NFC.

Move the logic whether lowering of deopt value requires a spill slot in
a separate lambda.

Reviewers: reames, dantrushin
Reviewed By: dantrushin
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D77629
---
 .../CodeGen/SelectionDAG/StatepointLowering.cpp    | 33 +++++++++++++---------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
index 8cb6090..ffe3563 100644
--- a/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -372,10 +372,11 @@ spillIncomingStatepointValue(SDValue Incoming, SDValue Chain,
 /// Lower a single value incoming to a statepoint node.  This value can be
 /// either a deopt value or a gc value, the handling is the same.  We special
 /// case constants and allocas, then fall back to spilling if required.
-static void lowerIncomingStatepointValue(SDValue Incoming, bool LiveInOnly,
-                                         SmallVectorImpl<SDValue> &Ops,
-                                         SmallVectorImpl<MachineMemOperand*> &MemRefs,
-                                         SelectionDAGBuilder &Builder) {
+static void
+lowerIncomingStatepointValue(SDValue Incoming, bool RequireSpillSlot,
+                             SmallVectorImpl<SDValue> &Ops,
+                             SmallVectorImpl<MachineMemOperand *> &MemRefs,
+                             SelectionDAGBuilder &Builder) {
   // Note: We know all of these spills are independent, but don't bother to
   // exploit that chain wise.  DAGCombine will happily do so as needed, so
   // doing it here would be a small compile time win at most.
@@ -401,8 +402,8 @@ static void lowerIncomingStatepointValue(SDValue Incoming, bool LiveInOnly,
     auto &MF = Builder.DAG.getMachineFunction();
     auto *MMO = getMachineMemOperand(MF, *FI);
     MemRefs.push_back(MMO);
-    
-  } else if (LiveInOnly) {
+
+  } else if (!RequireSpillSlot) {
     // If this value is live in (not live-on-return, or live-through), we can
     // treat it the same way patchpoint treats it's "live in" values.  We'll
     // end up folding some of these into stack references, but they'll be
@@ -492,13 +493,17 @@ lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops,
     return true; // conservative
   };
 
+  auto requireSpillSlot = [&](const Value *V) {
+    return !LiveInDeopt || isGCValue(V);
+  };
+
   // Before we actually start lowering (and allocating spill slots for values),
   // reserve any stack slots which we judge to be profitable to reuse for a
   // particular value.  This is purely an optimization over the code below and
   // doesn't change semantics at all.  It is important for performance that we
   // reserve slots for both deopt and gc values before lowering either.
   for (const Value *V : SI.DeoptState) {
-    if (!LiveInDeopt || isGCValue(V))
+    if (requireSpillSlot(V))
       reservePreviousStackSlotForValue(V, Builder);
   }
   for (unsigned i = 0; i < SI.Bases.size(); ++i) {
@@ -525,8 +530,8 @@ lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops,
     }
     if (!Incoming.getNode())
       Incoming = Builder.getValue(V);
-    const bool LiveInValue = LiveInDeopt && !isGCValue(V);
-    lowerIncomingStatepointValue(Incoming, LiveInValue, Ops, MemRefs, Builder);
+    lowerIncomingStatepointValue(Incoming, requireSpillSlot(V), Ops, MemRefs,
+                                 Builder);
   }
 
   // Finally, go ahead and lower all the gc arguments.  There's no prefixed
@@ -536,12 +541,14 @@ lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops,
   // (base[0], ptr[0], base[1], ptr[1], ...)
   for (unsigned i = 0; i < SI.Bases.size(); ++i) {
     const Value *Base = SI.Bases[i];
-    lowerIncomingStatepointValue(Builder.getValue(Base), /*LiveInOnly*/ false,
-                                 Ops, MemRefs, Builder);
+    lowerIncomingStatepointValue(Builder.getValue(Base),
+                                 /*RequireSpillSlot*/ true, Ops, MemRefs,
+                                 Builder);
 
     const Value *Ptr = SI.Ptrs[i];
-    lowerIncomingStatepointValue(Builder.getValue(Ptr), /*LiveInOnly*/ false,
-                                 Ops, MemRefs, Builder);
+    lowerIncomingStatepointValue(Builder.getValue(Ptr),
+                                 /*RequireSpillSlot*/ true, Ops, MemRefs,
+                                 Builder);
   }
 
   // If there are any explicit spill slots passed to the statepoint, record
-- 
2.7.4