From 3baef191ccefbf74bb1d7eab60a629fe350e21cf Mon Sep 17 00:00:00 2001
From: Kunal Pathak <Kunal.Pathak@microsoft.com>
Date: Wed, 9 Apr 2025 22:51:39 -0700
Subject: [PATCH 1/2] Force storing GC state until we see a labelled IG

---
 src/coreclr/jit/emit.cpp | 11 +++++++++++
 src/coreclr/jit/emit.h   |  8 ++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/coreclr/jit/emit.cpp b/src/coreclr/jit/emit.cpp
index e03ec89ac87777..0217608d874478 100644
--- a/src/coreclr/jit/emit.cpp
+++ b/src/coreclr/jit/emit.cpp
@@ -1007,8 +1007,14 @@ insGroup* emitter::emitSavIG(bool emitAdd)
         VarSetOps::Assign(emitComp, emitPrevGCrefVars, emitThisGCrefVars);
         emitPrevGCrefRegs = emitThisGCrefRegs;
         emitPrevByrefRegs = emitThisByrefRegs;
+    }
 
+    if (emitAddedLabel)
+    {
+        // Reset emitForceStoreGCState only after seeing label. It will keep
+        // marking IGs with IGF_GC_VARS flag until that.
         emitForceStoreGCState = false;
+        emitAddedLabel        = false;
     }
 
 #ifdef DEBUG
@@ -2839,6 +2845,11 @@ void* emitter::emitAddLabel(VARSET_VALARG_TP GCvars, regMaskTP gcrefRegs, regMas
         }
     }
 
+    if (emitForceStoreGCState)
+    {
+        emitAddedLabel = true;
+    }
+
     /* Create a new IG if the current one is non-empty */
 
     if (emitCurIGnonEmpty())
diff --git a/src/coreclr/jit/emit.h b/src/coreclr/jit/emit.h
index ef1fd2f701fc15..e76de2316c2c09 100644
--- a/src/coreclr/jit/emit.h
+++ b/src/coreclr/jit/emit.h
@@ -2761,6 +2761,14 @@ class emitter
 
     bool emitForceStoreGCState;
 
+    // This flag is used together with `emitForceStoreGCState`. After we set
+    // emitForceStoreGCState = true, we will mark `emitAddedLabel` to true whenever
+    // we see a label IG. In emitSavIG, we will reset `emitForceStoreGCState = false`
+    // only after seeing `emitAddedLabel == true`. Until then, we will keep recording
+    // GC_VARS on the IGs.
+
+    bool emitAddedLabel;
+
     // emitThis* variables are used during emission, to track GC updates
     // on a per-instruction basis. During code generation, per-instruction
     // tracking is done with variables gcVarPtrSetCur, gcRegGCrefSetCur,

From f2958eb087466a192402bce4652b256e2bbbd40a Mon Sep 17 00:00:00 2001
From: Kunal Pathak <Kunal.Pathak@microsoft.com>
Date: Thu, 10 Apr 2025 20:26:17 -0700
Subject: [PATCH 2/2] review feedback

---
 src/coreclr/jit/emit.cpp | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/src/coreclr/jit/emit.cpp b/src/coreclr/jit/emit.cpp
index 0217608d874478..3a7a98a96041b0 100644
--- a/src/coreclr/jit/emit.cpp
+++ b/src/coreclr/jit/emit.cpp
@@ -1007,14 +1007,14 @@ insGroup* emitter::emitSavIG(bool emitAdd)
         VarSetOps::Assign(emitComp, emitPrevGCrefVars, emitThisGCrefVars);
         emitPrevGCrefRegs = emitThisGCrefRegs;
         emitPrevByrefRegs = emitThisByrefRegs;
-    }
 
-    if (emitAddedLabel)
-    {
-        // Reset emitForceStoreGCState only after seeing label. It will keep
-        // marking IGs with IGF_GC_VARS flag until that.
-        emitForceStoreGCState = false;
-        emitAddedLabel        = false;
+        if (emitAddedLabel)
+        {
+            // Reset emitForceStoreGCState only after seeing label. It will keep
+            // marking IGs with IGF_GC_VARS flag until that.
+            emitForceStoreGCState = false;
+            emitAddedLabel        = false;
+        }
     }
 
 #ifdef DEBUG
@@ -1283,6 +1283,7 @@ void emitter::emitBegFN(bool hasFramePtr
     emitPrevByrefRegs = RBM_NONE;
 
     emitForceStoreGCState = false;
+    emitAddedLabel        = false;
 
 #ifdef DEBUG
 
@@ -2845,10 +2846,7 @@ void* emitter::emitAddLabel(VARSET_VALARG_TP GCvars, regMaskTP gcrefRegs, regMas
         }
     }
 
-    if (emitForceStoreGCState)
-    {
-        emitAddedLabel = true;
-    }
+    emitAddedLabel = true;
 
     /* Create a new IG if the current one is non-empty */