From 1d3f9f886288d9be08772ed348c382a479cf857f Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@sifive.com>
Date: Thu, 5 Dec 2024 12:56:36 -0800
Subject: [PATCH] [SelectionDAG] Stop storing EVTs in a function scoped static
 std::set. (#118715)

EVTs potentially contain a Type * that points into memory owned by an
LLVMContext. Storing them in a function scoped static means they may
outlive the LLVMContext they point to.

This std::set is used to unique single element VT lists containing a
single extended EVT. Single element VT list with a simple EVT are
uniqued by a separate cache indexed by the MVT::SimpleValueType enum. VT
lists with more than one element are uniqued by a FoldingSet owned by
the SelectionDAG object.

This patch moves the single element cache into SelectionDAG so that it
will be destroyed when SelectionDAG is destroyed.

Fixes #88233
---
 llvm/include/llvm/CodeGen/SelectionDAG.h       |  4 ++++
 llvm/include/llvm/CodeGen/SelectionDAGNodes.h  |  4 ++--
 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 17 +++++++----------
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 2e3507386df3..e97e01839f73 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -44,6 +44,7 @@
 #include <cstdint>
 #include <functional>
 #include <map>
+#include <set>
 #include <string>
 #include <tuple>
 #include <utility>
@@ -247,6 +248,9 @@ class SelectionDAG {
   BlockFrequencyInfo *BFI = nullptr;
   MachineModuleInfo *MMI = nullptr;
 
+  /// Extended EVTs used for single value VTLists.
+  std::set<EVT, EVT::compareRawBits> EVTs;
+
   /// List of non-single value types.
   FoldingSet<SDVTListNode> VTListMap;
 
diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
index 677b59e0c8fb..61f3c6329efc 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -664,7 +664,7 @@ private:
   DebugLoc debugLoc;
 
   /// Return a pointer to the specified value type.
-  static const EVT *getValueTypeList(EVT VT);
+  static const EVT *getValueTypeList(MVT VT);
 
   /// Index in worklist of DAGCombiner, or negative if the node is not in the
   /// worklist. -1 = not in worklist; -2 = not in worklist, but has already been
@@ -1124,7 +1124,7 @@ public:
   void addUse(SDUse &U) { U.addToList(&UseList); }
 
 protected:
-  static SDVTList getSDVTList(EVT VT) {
+  static SDVTList getSDVTList(MVT VT) {
     SDVTList Ret = { getValueTypeList(VT), 1 };
     return Ret;
   }
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 182529123ec6..1b39b75d2687 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -10623,7 +10623,10 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, SDVTList VTList,
 }
 
 SDVTList SelectionDAG::getVTList(EVT VT) {
-  return makeVTList(SDNode::getValueTypeList(VT), 1);
+  if (!VT.isExtended())
+    return makeVTList(SDNode::getValueTypeList(VT.getSimpleVT()), 1);
+
+  return makeVTList(&(*EVTs.insert(VT).first), 1);
 }
 
 SDVTList SelectionDAG::getVTList(EVT VT1, EVT VT2) {
@@ -12383,17 +12386,11 @@ namespace {
 
 /// getValueTypeList - Return a pointer to the specified value type.
 ///
-const EVT *SDNode::getValueTypeList(EVT VT) {
-  static std::set<EVT, EVT::compareRawBits> EVTs;
+const EVT *SDNode::getValueTypeList(MVT VT) {
   static EVTArray SimpleVTArray;
-  static sys::SmartMutex<true> VTMutex;
 
-  if (VT.isExtended()) {
-    sys::SmartScopedLock<true> Lock(VTMutex);
-    return &(*EVTs.insert(VT).first);
-  }
-  assert(VT.getSimpleVT() < MVT::VALUETYPE_SIZE && "Value type out of range!");
-  return &SimpleVTArray.VTs[VT.getSimpleVT().SimpleTy];
+  assert(VT < MVT::VALUETYPE_SIZE && "Value type out of range!");
+  return &SimpleVTArray.VTs[VT.SimpleTy];
 }
 
 /// hasNUsesOfValue - Return true if there are exactly NUSES uses of the