Track a missing place to reset alignment flag from BasicBlock

src/coreclr/jit/block.cpp

@@ -1678,6 +1678,6 @@ void BasicBlock::unmarkLoopAlign(Compiler* compiler DEBUG_ARG(const char* reason
     {
         compiler->loopAlignCandidates--;
         bbFlags &= ~BBF_LOOP_ALIGN;
-        JITDUMP("Unmarking LOOP_ALIGN from " FMT_BB ". Reason= %s.", bbNum, reason);
+        JITDUMP("Unmarking LOOP_ALIGN from " FMT_BB ". Reason= %s.\n", bbNum, reason);
     }
 }

src/coreclr/jit/compiler.cpp

@@ -5242,6 +5242,7 @@ void Compiler::placeLoopAlignInstructions()
     }
 
     int loopsToProcess = loopAlignCandidates;
+    JITDUMP("Inside placeLoopAlignInstructions for %d loops.\n", loopAlignCandidates);
 
     // Add align only if there were any loops that needed alignment
     weight_t    minBlockSoFar = BB_MAX_WEIGHT;

src/coreclr/jit/fgopt.cpp

@@ -5934,6 +5934,9 @@ bool Compiler::fgUpdateFlowGraph(bool doTailDuplication)
                         // Update the loop table if we removed the bottom of a loop, for example.
                         fgUpdateLoopsAfterCompacting(block, bNext);
 
+                        // If this block was aligned, unmark it
+                        bNext->unmarkLoopAlign(this DEBUG_ARG("Optimized jump"));
+
                         // If this is the first Cold basic block update fgFirstColdBlock
                         if (bNext == fgFirstColdBlock)
                         {

src/tests/JIT/Directed/LoopAlignment/LoopsToProcess.cs

@@ -0,0 +1,141 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+//
+// Note: This test case is found by Antigen. It catches a scenario where we were not accounting
+//       for total loop candidates to align.
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+public class TestClass_Loops
+{
+    public struct S1
+    {
+        public struct S1_D1_F1
+        {
+            public decimal decimal_0;
+        }
+        public long long_1;
+    }
+    public struct S2
+    {
+        public decimal decimal_2;
+    }
+    static byte s_byte_4 = 1;
+    static decimal s_decimal_6 = 5.1428571428571428571428571429m;
+    static short s_short_8 = 5;
+    static sbyte s_sbyte_11 = -1;
+    static ulong s_ulong_16 = 2;
+    static S1.S1_D1_F1 s_s1_s1_d1_f1_17 = new S1.S1_D1_F1();
+    static S1 s_s1_18 = new S1();
+    static S2 s_s2_19 = new S2();
+    byte byte_21 = 5;
+    decimal decimal_23 = -1.987654320987654320987654321m;
+    short short_25 = 0;
+    long long_27 = 5;
+    float float_29 = -0.9423077f;
+    S1 s1_35 = new S1();
+    S2 s2_36 = new S2();
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public decimal LeafMethod3()
+    {
+        return 0.5m;
+    }
+
+    public float LeafMethod9()
+    {
+        return 0.5f;
+    }
+
+    public uint LeafMethod12()
+    {
+        return 1;
+    }
+
+    public ulong Method18(S2 p_s2_492, ref decimal p_decimal_493, out uint p_uint_494, ref float p_float_495, ref int p_int_496, short p_short_497, out uint p_uint_498, ref S1 p_s1_499)
+    {
+        p_uint_498 = (uint)10;
+        p_uint_494=0;
+        return 5;
+    }
+
+    public float Method21(ref S1 p_s1_565, ref byte p_byte_566, S2 p_s2_567, ref S1 p_s1_568, ref S1.S1_D1_F1 p_s1_s1_d1_f1_569, S1 p_s1_570, out S1.S1_D1_F1 p_s1_s1_d1_f1_571, ref S2 p_s2_572)
+    {
+        p_s1_s1_d1_f1_571 = s_s1_s1_d1_f1_17;
+        return -4.928571f;
+    }
+
+    public S2 Method35(ref S1 p_s1_952, ref sbyte p_sbyte_953, ref S1.S1_D1_F1 p_s1_s1_d1_f1_954)
+    {
+        unchecked
+        {
+            S2 s2_971 = new S2();
+            return s2_36;
+        }
+    }
+
+    public S1 Method60(ref decimal p_decimal_1639, out float p_float_1640, ref byte p_byte_1641, out S2 p_s2_1642, S1.S1_D1_F1 p_s1_s1_d1_f1_1643, ref S1 p_s1_1644, out S2 p_s2_1645, S2 p_s2_1646, ref ulong p_ulong_1647, out ulong p_ulong_1648, ref S2 p_s2_1649, out S2 p_s2_1650)
+    {
+        unchecked
+        {
+            char char_1653 = '5';
+            decimal decimal_1654 = 5.0333333333333333333333333333m;
+            double double_1655 = 1;
+            short short_1656 = 1;
+            int int_1657 = -1;
+            float float_1660 = 5.090909f;
+            uint uint_1663 = 5;
+            S1.S1_D1_F1 s1_s1_d1_f1_1665 = new S1.S1_D1_F1();
+            S1 s1_1666 = new S1();
+            S2 s2_1667 = new S2();
+            S2 s2_1668 = s2_1667;
+            p_float_1640 = ((float)(((float)(float_1660 /= ((float)((((float)(float_29 - ((float)(LeafMethod9() * float_1660))))) + 89)))) % ((float)((Method21(ref s1_35, ref s_byte_4, s_s2_19, ref s1_35, ref p_s1_s1_d1_f1_1643, s_s1_18, out s_s1_s1_d1_f1_17, ref s2_1667)) + 45))));
+            p_s2_1642 = s2_36;
+            p_s2_1645 = s_s2_19;
+            p_ulong_1648 = Method18(s2_36, ref decimal_23, out uint_1663, ref p_float_1640, ref int_1657, ((short)(short_1656 % ((short)((((short)(short_25 - s_short_8))) + 35)))), out uint_1663, ref s_s1_18);
+            p_s2_1650 = s2_36;
+            switch (((char)(char_1653 = 'M')))
+            {
+                case 'Y':
+                    {
+                        S1 s1_1669 = s_s1_18;
+                        break;
+                    }
+                case 'I':
+                    {
+                        break;
+                    }
+                case 'J':
+                    {
+                        long_27 >>= int_1657;
+                        s1_s1_d1_f1_1665.decimal_0 %= ((decimal)((((decimal)(((decimal)(s_s2_19.decimal_2 += ((decimal)(((decimal)(decimal_1654 - -1.9841269841269841269841269841m)) + ((decimal)(s_decimal_6 *= s2_1668.decimal_2)))))) * ((decimal)(s_s2_19.decimal_2 *= ((decimal)(s2_36.decimal_2 += ((decimal)(LeafMethod3() + LeafMethod3()))))))))) + 40));
+                        break;
+                    }
+                default:
+                    {
+                        Method35(ref s1_35, ref s_sbyte_11, ref s_s1_s1_d1_f1_17);
+                        break;
+                    }
+            }
+            return p_s1_1644;
+        }
+    }
+
+    public void Method0()
+    {
+        unchecked
+        {
+            ulong ulong_2733 = 37;
+            S1.S1_D1_F1 s1_s1_d1_f1_2734 = new S1.S1_D1_F1();
+            S1 s1_2735 = new S1();
+            S1 s1_2736 = s1_2735;
+            S2 s2_2737 = new S2();
+            s_s1_18 = Method60(ref s2_2737.decimal_2, out float_29, ref byte_21, out s_s2_19, s1_s1_d1_f1_2734, ref s_s1_18, out s_s2_19, s2_2737, ref ulong_2733, out s_ulong_16, ref s2_2737, out s2_2737);
+            return;
+        }
+    }
+    public static void Main(string[] args)
+    {
+        new TestClass_Loops().Method0();
+    }
+}

src/tests/JIT/Directed/LoopAlignment/LoopsToProcess.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <CLRTestPriority>1</CLRTestPriority>
+  </PropertyGroup>
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+   <PropertyGroup>
+    <CLRTestBatchPreCommands><![CDATA[
+$(CLRTestBatchPreCommands)
+set COMPlus_JitAggressiveInlining=1
+]]></CLRTestBatchPreCommands>
+    <BashCLRTestPreCommands><![CDATA[
+$(BashCLRTestPreCommands)
+export COMPlus_JitAggressiveInlining=1
+]]></BashCLRTestPreCommands>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="LoopsToProcess.cs" />
+  </ItemGroup>
+</Project>