https://github.com/inbelic updated 
https://github.com/llvm/llvm-project/pull/176793

>From 007a060105b094abd17802246cd16835934d391b Mon Sep 17 00:00:00 2001
From: Finn Plummer <[email protected]>
Date: Mon, 19 Jan 2026 09:31:01 -0800
Subject: [PATCH 1/5] [SemaHLSL] Verify assignment of local resources

---
 .../clang/Basic/DiagnosticSemaKinds.td        |  3 +
 clang/include/clang/Sema/SemaHLSL.h           | 15 ++++
 clang/lib/Sema/SemaHLSL.cpp                   | 76 +++++++++++++++++--
 .../test/SemaHLSL/local_resource_binding.hlsl | 56 ++++++++++++++
 .../SemaHLSL/local_resource_binding_errs.hlsl | 41 ++++++++++
 5 files changed, 185 insertions(+), 6 deletions(-)
 create mode 100644 clang/test/SemaHLSL/local_resource_binding.hlsl
 create mode 100644 clang/test/SemaHLSL/local_resource_binding_errs.hlsl

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index eb7a608f798b8..87673e944fc0d 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -13431,6 +13431,9 @@ def 
err_hlsl_incomplete_resource_array_in_function_param: Error<
   "incomplete resource array in a function parameter">;
 def err_hlsl_assign_to_global_resource: Error<
   "assignment to global resource variable %0 is not allowed">;
+def err_hlsl_assigning_local_resource_is_not_unique
+    : Error<"assignment to local resource %0 is not to same unique global "
+            "resource">;
 
 def err_hlsl_push_constant_unique
     : Error<"cannot have more than one push constant block">;
diff --git a/clang/include/clang/Sema/SemaHLSL.h 
b/clang/include/clang/Sema/SemaHLSL.h
index 99d8ed137b0c2..48daebbf61c90 100644
--- a/clang/include/clang/Sema/SemaHLSL.h
+++ b/clang/include/clang/Sema/SemaHLSL.h
@@ -132,6 +132,14 @@ class SemaHLSL : public SemaBase {
   bool ActOnUninitializedVarDecl(VarDecl *D);
   void ActOnEndOfTranslationUnit(TranslationUnitDecl *TU);
   void CheckEntryPoint(FunctionDecl *FD);
+
+  // Return an info if the expr has common global binding info; returns
+  // std::nullopt if the expr refers to non-unique global bindings, returns
+  // nullptr if it isn't refer to any global binding, otherwise it returns
+  // a reference to the global binding info.
+  std::optional<const DeclBindingInfo *> GetGlobalBinding(Expr *E);
+
+  // Return true if everything is ok; returns false if there was an error.
   bool CheckResourceBinOp(BinaryOperatorKind Opc, Expr *LHSExpr, Expr *RHSExpr,
                           SourceLocation Loc);
 
@@ -230,6 +238,13 @@ class SemaHLSL : public SemaBase {
   // List of all resource bindings
   ResourceBindings Bindings;
 
+  // Map of local resource variables to their used global resource.
+  //
+  // The Binding can be a nullptr, in which case, the variable has not be
+  // initialized or assigned to yet.
+  llvm::DenseMap<const VarDecl *, const DeclBindingInfo *>
+      LocalResourceBindings;
+
   // Global declaration collected for the $Globals default constant
   // buffer which will be created at the end of the translation unit.
   llvm::SmallVector<Decl *> DefaultCBufferDecls;
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index f15b274a65a53..cd00167ceb72f 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -4398,7 +4398,35 @@ bool SemaHLSL::ActOnUninitializedVarDecl(VarDecl *VD) {
   return false;
 }
 
-// Return true if everything is ok; returns false if there was an error.
+std::optional<const DeclBindingInfo *> SemaHLSL::GetGlobalBinding(Expr *E) {
+  if (auto *Ternary = dyn_cast<ConditionalOperator>(E)) {
+    auto TrueInfo = GetGlobalBinding(Ternary->getTrueExpr());
+    auto FalseInfo = GetGlobalBinding(Ternary->getFalseExpr());
+    if (!TrueInfo || !FalseInfo)
+      return std::nullopt;
+    if (*TrueInfo != *FalseInfo)
+      return std::nullopt;
+    return TrueInfo;
+  }
+
+  if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E))
+    E = ASE->getBase()->IgnoreParenImpCasts();
+
+  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens()))
+    if (VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
+      const Type *Ty = VD->getType()->getUnqualifiedDesugaredType();
+      if (Ty->isArrayType())
+        Ty = Ty->getArrayElementTypeNoTypeQual();
+      if (const auto *AttrResType =
+              HLSLAttributedResourceType::findHandleTypeOnResource(Ty)) {
+        ResourceClass RC = AttrResType->getAttrs().ResourceClass;
+        return Bindings.getDeclBindingInfo(VD, RC);
+      }
+    }
+
+  return nullptr;
+}
+
 bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind Opc, Expr *LHSExpr,
                                   Expr *RHSExpr, SourceLocation Loc) {
   assert((LHSExpr->getType()->isHLSLResourceRecord() ||
@@ -4412,14 +4440,37 @@ bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind 
Opc, Expr *LHSExpr,
   while (auto *ASE = dyn_cast<ArraySubscriptExpr>(E))
     E = ASE->getBase()->IgnoreParenImpCasts();
 
+  auto RHSBinding = GetGlobalBinding(RHSExpr);
+  if (!RHSBinding) {
+    SemaRef.Diag(Loc, diag::err_hlsl_assigning_local_resource_is_not_unique)
+        << RHSExpr;
+    return false;
+  }
+
   // Report error if LHS is a non-static resource declared at a global scope.
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
     if (VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
-      if (VD->hasGlobalStorage() && VD->getStorageClass() != SC_Static) {
-        // assignment to global resource is not allowed
-        SemaRef.Diag(Loc, diag::err_hlsl_assign_to_global_resource) << VD;
-        SemaRef.Diag(VD->getLocation(), diag::note_var_declared_here) << VD;
-        return false;
+      if (VD->getStorageClass() != SC_Static) {
+        if (VD->hasGlobalStorage()) {
+          // assignment to global resource is not allowed
+          SemaRef.Diag(Loc, diag::err_hlsl_assign_to_global_resource) << VD;
+          SemaRef.Diag(VD->getLocation(), diag::note_var_declared_here) << VD;
+          return false;
+        }
+
+        // Ensure assignment to a non-static local resource does not conflict
+        // with previous assignments to global resources
+        const DeclBindingInfo *LHSBinding = LocalResourceBindings[VD];
+        if (!LHSBinding) {
+          // occurs when local resource was instantiated without an expression
+          LocalResourceBindings[VD] = *RHSBinding;
+        } else if (LHSBinding != *RHSBinding) {
+          SemaRef.Diag(Loc,
+                       diag::err_hlsl_assigning_local_resource_is_not_unique)
+              << RHSExpr;
+          SemaRef.Diag(VD->getLocation(), diag::note_var_declared_here) << VD;
+          return false;
+        }
       }
     }
   }
@@ -4797,6 +4848,19 @@ bool SemaHLSL::transformInitList(const InitializedEntity 
&Entity,
 }
 
 bool SemaHLSL::handleInitialization(VarDecl *VDecl, Expr *&Init) {
+  // If initializing a local resource, register the binding it is using
+  if (VDecl->getType()->isHLSLResourceRecord() && !VDecl->hasGlobalStorage())
+    if (auto *InitExpr = Init) {
+      if (auto Binding = GetGlobalBinding(InitExpr)) {
+        LocalResourceBindings.insert({VDecl, *Binding});
+      } else {
+        SemaRef.Diag(Init->getBeginLoc(),
+                     diag::err_hlsl_assigning_local_resource_is_not_unique)
+            << Init;
+        return false;
+      }
+    }
+
   const HLSLVkConstantIdAttr *ConstIdAttr =
       VDecl->getAttr<HLSLVkConstantIdAttr>();
   if (!ConstIdAttr)
diff --git a/clang/test/SemaHLSL/local_resource_binding.hlsl 
b/clang/test/SemaHLSL/local_resource_binding.hlsl
new file mode 100644
index 0000000000000..3059452b49ef0
--- /dev/null
+++ b/clang/test/SemaHLSL/local_resource_binding.hlsl
@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-library -verify %s
+
+// expected-no-diagnostics
+
+RWBuffer<int> In : register(u0);
+RWStructuredBuffer<int> Out0 : register(u1);
+RWStructuredBuffer<int> Out1 : register(u2);
+RWStructuredBuffer<int> OutArr[];
+
+cbuffer c {
+    bool cond;
+};
+
+void no_initial_assignment(int idx) {
+    RWStructuredBuffer<int> Out;
+    if (cond) {
+        Out = Out1;
+    }
+    Out[idx] = In[idx];
+}
+
+void same_assignment(int idx) {
+    RWStructuredBuffer<int> Out = Out1;
+    if (cond) {
+        Out = Out1;
+    }
+    Out[idx] = In[idx];
+}
+
+void conditional_initialization_with_index(int idx) {
+    RWStructuredBuffer<int> Out = cond ? OutArr[0] : OutArr[1];
+    Out[idx] = In[idx];
+}
+
+void conditional_assignment_with_index(int idx) {
+    RWStructuredBuffer<int> Out;
+       if (cond) {
+               Out = OutArr[0];
+       } else {
+               Out = OutArr[1];
+       }
+    Out[idx] = In[idx];
+}
+
+void reassignment(int idx) {
+    RWStructuredBuffer<int> Out = Out0;
+       if (cond) {
+               Out = Out0;
+       }
+       Out[idx] = In[idx];
+}
+
+void conditional_result_in_same(int idx) {
+    RWStructuredBuffer<int> Out = cond ? Out0 : Out0;
+       Out[idx] = In[idx];
+}
diff --git a/clang/test/SemaHLSL/local_resource_binding_errs.hlsl 
b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
new file mode 100644
index 0000000000000..163d3c4493ca2
--- /dev/null
+++ b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-library -verify %s
+
+RWBuffer<int> In : register(u0);
+RWStructuredBuffer<int> Out0 : register(u1);
+RWStructuredBuffer<int> Out1 : register(u2);
+RWStructuredBuffer<int> OutArr[];
+
+cbuffer c {
+    bool cond;
+};
+
+void conditional_initialization(int idx) {
+    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to same unique global resource}}
+    RWStructuredBuffer<int> Out = cond ? Out0 : Out1;
+    Out[idx] = In[idx];
+}
+
+void branched_assignment(int idx) {
+    RWStructuredBuffer<int> Out = Out0; // expected-note {{variable 'Out' is 
declared here}}
+    if (cond) {
+        // expected-error@+1 {{assignment to local resource 'Out1' is not to 
same unique global resource}}
+        Out = Out1;
+    }
+    Out[idx] = In[idx];
+}
+
+void branched_assignment_with_array(int idx) {
+    RWStructuredBuffer<int> Out = Out0; // expected-note {{variable 'Out' is 
declared here}}
+    if (cond) {
+        // expected-error@+1 {{assignment to local resource 'OutArr[0]' is not 
to same unique global resource}}
+        Out = OutArr[0];
+    }
+    Out[idx] = In[idx];
+}
+
+void conditional_assignment(int idx) {
+    RWStructuredBuffer<int> Out;
+    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to same unique global resource}}
+    Out = cond ? Out0 : Out1;
+    Out[idx] = In[idx];
+}

>From 4c4fcf9936aa61a1766dd6bab147c7137baf8292 Mon Sep 17 00:00:00 2001
From: Finn Plummer <[email protected]>
Date: Mon, 19 Jan 2026 11:24:18 -0800
Subject: [PATCH 2/5] review: fix-up comments

Co-authored-by: Deric C. <[email protected]>
---
 clang/include/clang/Sema/SemaHLSL.h | 4 ++--
 clang/lib/Sema/SemaHLSL.cpp         | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/include/clang/Sema/SemaHLSL.h 
b/clang/include/clang/Sema/SemaHLSL.h
index 48daebbf61c90..d12dcc596989e 100644
--- a/clang/include/clang/Sema/SemaHLSL.h
+++ b/clang/include/clang/Sema/SemaHLSL.h
@@ -240,8 +240,8 @@ class SemaHLSL : public SemaBase {
 
   // Map of local resource variables to their used global resource.
   //
-  // The Binding can be a nullptr, in which case, the variable has not be
-  // initialized or assigned to yet.
+  // The binding can be a nullptr, in which case, the variable has yet to be
+  // initialized or assigned to.
   llvm::DenseMap<const VarDecl *, const DeclBindingInfo *>
       LocalResourceBindings;
 
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index cd00167ceb72f..c41e48128cef9 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -4452,7 +4452,7 @@ bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind Opc, 
Expr *LHSExpr,
     if (VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
       if (VD->getStorageClass() != SC_Static) {
         if (VD->hasGlobalStorage()) {
-          // assignment to global resource is not allowed
+          // Assignment to a global resource is not allowed.
           SemaRef.Diag(Loc, diag::err_hlsl_assign_to_global_resource) << VD;
           SemaRef.Diag(VD->getLocation(), diag::note_var_declared_here) << VD;
           return false;
@@ -4462,7 +4462,7 @@ bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind Opc, 
Expr *LHSExpr,
         // with previous assignments to global resources
         const DeclBindingInfo *LHSBinding = LocalResourceBindings[VD];
         if (!LHSBinding) {
-          // occurs when local resource was instantiated without an expression
+          // LHSBinding is a nullptr when the local resource is instantiated 
without an expression.
           LocalResourceBindings[VD] = *RHSBinding;
         } else if (LHSBinding != *RHSBinding) {
           SemaRef.Diag(Loc,
@@ -4848,7 +4848,7 @@ bool SemaHLSL::transformInitList(const InitializedEntity 
&Entity,
 }
 
 bool SemaHLSL::handleInitialization(VarDecl *VDecl, Expr *&Init) {
-  // If initializing a local resource, register the binding it is using
+  // If initializing a local resource, register the binding it is using.
   if (VDecl->getType()->isHLSLResourceRecord() && !VDecl->hasGlobalStorage())
     if (auto *InitExpr = Init) {
       if (auto Binding = GetGlobalBinding(InitExpr)) {

>From 5eca470288d496b2d0f64e4db6b061aed862f0e4 Mon Sep 17 00:00:00 2001
From: Finn Plummer <[email protected]>
Date: Mon, 19 Jan 2026 11:26:32 -0800
Subject: [PATCH 3/5] review: fix-up diagnostic message

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td     | 2 +-
 clang/test/SemaHLSL/local_resource_binding_errs.hlsl | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td 
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 87673e944fc0d..5e206d84ab7c0 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -13432,7 +13432,7 @@ def 
err_hlsl_incomplete_resource_array_in_function_param: Error<
 def err_hlsl_assign_to_global_resource: Error<
   "assignment to global resource variable %0 is not allowed">;
 def err_hlsl_assigning_local_resource_is_not_unique
-    : Error<"assignment to local resource %0 is not to same unique global "
+    : Error<"assignment to local resource %0 is not to the same unique global "
             "resource">;
 
 def err_hlsl_push_constant_unique
diff --git a/clang/test/SemaHLSL/local_resource_binding_errs.hlsl 
b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
index 163d3c4493ca2..807886d77bc7a 100644
--- a/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
+++ b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
@@ -10,7 +10,7 @@ cbuffer c {
 };
 
 void conditional_initialization(int idx) {
-    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to same unique global resource}}
+    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to the same unique global resource}}
     RWStructuredBuffer<int> Out = cond ? Out0 : Out1;
     Out[idx] = In[idx];
 }
@@ -18,7 +18,7 @@ void conditional_initialization(int idx) {
 void branched_assignment(int idx) {
     RWStructuredBuffer<int> Out = Out0; // expected-note {{variable 'Out' is 
declared here}}
     if (cond) {
-        // expected-error@+1 {{assignment to local resource 'Out1' is not to 
same unique global resource}}
+        // expected-error@+1 {{assignment to local resource 'Out1' is not to 
same the unique global resource}}
         Out = Out1;
     }
     Out[idx] = In[idx];
@@ -27,7 +27,7 @@ void branched_assignment(int idx) {
 void branched_assignment_with_array(int idx) {
     RWStructuredBuffer<int> Out = Out0; // expected-note {{variable 'Out' is 
declared here}}
     if (cond) {
-        // expected-error@+1 {{assignment to local resource 'OutArr[0]' is not 
to same unique global resource}}
+        // expected-error@+1 {{assignment to local resource 'OutArr[0]' is not 
to the same unique global resource}}
         Out = OutArr[0];
     }
     Out[idx] = In[idx];
@@ -35,7 +35,7 @@ void branched_assignment_with_array(int idx) {
 
 void conditional_assignment(int idx) {
     RWStructuredBuffer<int> Out;
-    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to same unique global resource}}
+    // expected-error@+1 {{assignment to local resource 'cond ? Out0 : Out1' 
is not to the same unique global resource}}
     Out = cond ? Out0 : Out1;
     Out[idx] = In[idx];
 }

>From 8d0f91924d97fcddf72c76781b5f3af137294533 Mon Sep 17 00:00:00 2001
From: Finn Plummer <[email protected]>
Date: Mon, 19 Jan 2026 11:26:47 -0800
Subject: [PATCH 4/5] clang-format

---
 clang/lib/Sema/SemaHLSL.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index c41e48128cef9..021745ba26430 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -4462,7 +4462,8 @@ bool SemaHLSL::CheckResourceBinOp(BinaryOperatorKind Opc, 
Expr *LHSExpr,
         // with previous assignments to global resources
         const DeclBindingInfo *LHSBinding = LocalResourceBindings[VD];
         if (!LHSBinding) {
-          // LHSBinding is a nullptr when the local resource is instantiated 
without an expression.
+          // LHSBinding is a nullptr when the local resource is instantiated
+          // without an expression.
           LocalResourceBindings[VD] = *RHSBinding;
         } else if (LHSBinding != *RHSBinding) {
           SemaRef.Diag(Loc,

>From 5c7f60d6c75f0954459a118991f73203ab430e06 Mon Sep 17 00:00:00 2001
From: Finn Plummer <[email protected]>
Date: Mon, 19 Jan 2026 11:54:03 -0800
Subject: [PATCH 5/5] fix typo, whoops

---
 clang/test/SemaHLSL/local_resource_binding_errs.hlsl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/SemaHLSL/local_resource_binding_errs.hlsl 
b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
index 807886d77bc7a..ad9a46b865965 100644
--- a/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
+++ b/clang/test/SemaHLSL/local_resource_binding_errs.hlsl
@@ -18,7 +18,7 @@ void conditional_initialization(int idx) {
 void branched_assignment(int idx) {
     RWStructuredBuffer<int> Out = Out0; // expected-note {{variable 'Out' is 
declared here}}
     if (cond) {
-        // expected-error@+1 {{assignment to local resource 'Out1' is not to 
same the unique global resource}}
+        // expected-error@+1 {{assignment to local resource 'Out1' is not to 
the same unique global resource}}
         Out = Out1;
     }
     Out[idx] = In[idx];

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