Revert removal of SuppressGCTransition from SystemNative_GetTimestamp()

src/System.Private.CoreLib/shared/Interop/Unix/System.Native/Interop.GetTimestamp.cs

@@ -12,7 +12,7 @@ internal static partial class Sys
         internal static extern ulong GetTimestampResolution();
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetTimestamp", ExactSpelling = true)]
-        // [SuppressGCTransition] // https://github.com/dotnet/coreclr/issues/27465
+        [SuppressGCTransition]
         internal static extern ulong GetTimestamp();
     }
 }

src/jit/compiler.h

@@ -4827,7 +4827,7 @@ class Compiler
     bool fgGCPollsCreated;
     void fgMarkGCPollBlocks();
     void fgCreateGCPolls();
-    bool fgCreateGCPoll(GCPollType pollType, BasicBlock* block);
+    bool fgCreateGCPoll(GCPollType pollType, BasicBlock* block, Statement* stmt = nullptr);
 
     // Requires that "block" is a block that returns from
     // a finally.  Returns the number of successors (jump targets of

src/jit/flowgraph.cpp

@@ -3858,7 +3858,7 @@ void Compiler::fgCreateGCPolls()
  *  a basic block.
  */
 
-bool Compiler::fgCreateGCPoll(GCPollType pollType, BasicBlock* block)
+bool Compiler::fgCreateGCPoll(GCPollType pollType, BasicBlock* block, Statement* stmt)
 {
     bool createdPollBlocks;
 
@@ -3883,15 +3883,44 @@ bool Compiler::fgCreateGCPoll(GCPollType pollType, BasicBlock* block)
         pollType = GCPOLL_CALL;
     }
 
+#ifdef DEBUG
+    // If a statment was supplied it should be contained in the block.
+    if (stmt != nullptr)
+    {
+        bool containsStmt = false;
+        for (Statement* stmtMaybe : block->Statements())
+        {
+            containsStmt = (stmtMaybe == stmt);
+            if (containsStmt)
+            {
+                break;
+            }
+        }
+
+        assert(containsStmt);
+    }
+#endif
+
     if (GCPOLL_CALL == pollType)
     {
         createdPollBlocks = false;
         GenTreeCall* call = gtNewHelperCallNode(CORINFO_HELP_POLL_GC, TYP_VOID);
         GenTree*     temp = fgMorphCall(call);
 
-        // for BBJ_ALWAYS I don't need to insert it before the condition.  Just append it.
-        if (block->bbJumpKind == BBJ_ALWAYS)
+        if (stmt != nullptr)
+        {
+            // The GC_POLL should be inserted relative to the supplied statement. The safer
+            // location for the insertion is prior to the current statement since the supplied
+            // statement could be a GT_JTRUE (see fgNewStmtNearEnd() for more details).
+            Statement* newStmt = gtNewStmt(temp);
+
+            // Set the GC_POLL statement to have the same IL offset at the subsequent one.
+            newStmt->SetILOffsetX(stmt->GetILOffsetX());
+            fgInsertStmtBefore(block, stmt, newStmt);
+        }
+        else if (block->bbJumpKind == BBJ_ALWAYS)
         {
+            // for BBJ_ALWAYS I don't need to insert it before the condition.  Just append it.
             fgNewStmtAtEnd(block, temp);
         }
         else

src/jit/morph.cpp

@@ -8226,7 +8226,7 @@ GenTree* Compiler::fgMorphCall(GenTreeCall* call)
     if (fgGlobalMorph && call->IsUnmanaged() && call->IsSuppressGCTransition())
     {
         // Insert a GC poll.
-        bool insertedBB = fgCreateGCPoll(GCPOLL_CALL, compCurBB);
+        bool insertedBB = fgCreateGCPoll(GCPOLL_CALL, compCurBB, compCurStmt);
         assert(!insertedBB); // No new block should be inserted
     }
 

tests/src/JIT/Methodical/gc_poll/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required (VERSION 2.6) 
+project (GCPollNative)
+
+set(SOURCES 
+    GCPollNative.cpp 
+) 
+
+add_library (GCPollNative SHARED ${SOURCES})
+
+# add the install targets 
+install (TARGETS GCPollNative DESTINATION bin) 

tests/src/JIT/Methodical/gc_poll/GCPollNative.cpp

@@ -0,0 +1,44 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#include <cstdio>
+#include <cstdint>
+#include <atomic>
+
+#if defined(_MSC_VER)
+
+#define STDMETHODCALLTYPE __stdcall
+#define EXPORT(type) extern "C" type __declspec(dllexport)
+
+#else // !defined(_MSC_VER)
+
+#ifdef __i386__
+#define STDMETHODCALLTYPE __attribute__((stdcall))
+#else
+#define STDMETHODCALLTYPE 
+#endif
+#define EXPORT(type) extern "C" __attribute__((visibility("default"))) type
+
+#endif // defined(_MSC_VER)
+
+namespace
+{
+    std::atomic<uint64_t> _n{ 0 };
+
+    template<typename T>
+    T NextUInt(T t)
+    {
+        return (T)((++_n) + t);
+    }
+}
+
+EXPORT(uint32_t) STDMETHODCALLTYPE NextUInt32(uint32_t t)
+{
+    return NextUInt(t);
+}
+
+EXPORT(uint64_t) STDMETHODCALLTYPE NextUInt64(uint64_t t)
+{
+    return NextUInt(t);
+}

tests/src/JIT/Methodical/gc_poll/InsertGCPoll.cs

@@ -0,0 +1,108 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.InteropServices;
+
+static class GCPollNative
+{
+    // Simple function that can be marked as SuppressGCTransition which will
+    // result in a GCPoll insertion.
+    [DllImport(nameof(GCPollNative))]
+    [SuppressGCTransition]
+    public static extern uint NextUInt32(uint n);
+
+    // Simple function that can be marked as SuppressGCTransition which will
+    // result in a GCPoll insertion.
+    [DllImport(nameof(GCPollNative))]
+    [SuppressGCTransition]
+    public static extern ulong NextUInt64(ulong n);
+}
+
+class InsertGCPoll
+{
+    private static int PropNextInt32 => (int)GCPollNative.NextUInt32(0);
+    private static long PropNextInt64 => (long)GCPollNative.NextUInt64(0);
+
+    private static void AccessAsProperty32()
+    {
+        int a = PropNextInt32;
+        int b = PropNextInt32;
+        DisplayValues(a, b);
+    }
+
+    private static void AccessAsProperty64()
+    {
+        long a = PropNextInt64;
+        long b = PropNextInt64;
+        DisplayValues(a, b);
+    }
+
+    private static void DisplayValues<T>(T a, T b)
+    {
+        Console.WriteLine($"{a} {b}");
+    }
+
+    private static void BranchOnProperty32()
+    {
+        if (-1 == PropNextInt32)
+        {
+            Console.WriteLine("");
+        }
+    }
+
+    private static void BranchOnProperty64()
+    {
+        if (-1 == PropNextInt64)
+        {
+            Console.WriteLine("");
+        }
+    }
+
+    private static void CompoundStatementBranchOnProperty()
+    {
+        if (-1 == (PropNextInt64 + PropNextInt32 - PropNextInt64 + PropNextInt64 - PropNextInt32))
+        {
+            Console.WriteLine("");
+        }
+    }
+
+    private static void LoopOn32()
+    {
+        uint i = 0;
+        for (int j = 0; j < 10 || i < 32; ++j)
+        {
+            i += GCPollNative.NextUInt32(1);
+        }
+    }
+
+    private static void LoopOn64()
+    {
+        ulong i = 0;
+        for (int j = 0; j < 10 || i < 32; ++j)
+        {
+            i += GCPollNative.NextUInt64(1);
+        }
+    }
+
+    public static int Main()
+    {
+        try
+        {
+            AccessAsProperty32();
+            AccessAsProperty64();
+            BranchOnProperty32();
+            BranchOnProperty64();
+            CompoundStatementBranchOnProperty();
+            LoopOn32();
+            LoopOn64();
+        }
+        catch (Exception e)
+        {
+            Console.WriteLine(e.ToString());
+            return 101;
+        }
+        return 100;
+    }
+}

tests/src/JIT/Methodical/gc_poll/InsertGCPoll.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+  </PropertyGroup>
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="InsertGCPoll.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="CMakeLists.txt" />
+  </ItemGroup>
+</Project>