[clang] [CIR] Upstream support for SubstNonTypeTemplateParmExpr (PR #146751)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/146751

Upstream support for SubstNonTypeTemplateParmExpr

>From 09eb48db09711dd0a88d37b07eb0873c939c9176 Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Wed, 2 Jul 2025 20:02:35 +0200
Subject: [PATCH] [CIR] Upstream support for SubstNonTypeTemplateParmExpr

---
 clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp    |  5 ++++
 .../CIR/CodeGen/non-type-template-param.cpp   | 27 +++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 clang/test/CIR/CodeGen/non-type-template-param.cpp

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index b76b703a79fe8..10c485c85e22a 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -371,6 +371,11 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     return builder.create<cir::CastOp>(src.getLoc(), fullDstTy, *castKind, src);
   }
 
+  mlir::Value
+  VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *e) {
+    return Visit(e->getReplacement());
+  }
+
   mlir::Value VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *e);
   mlir::Value
   VisitAbstractConditionalOperator(const AbstractConditionalOperator *e);
diff --git a/clang/test/CIR/CodeGen/non-type-template-param.cpp b/clang/test/CIR/CodeGen/non-type-template-param.cpp
new file mode 100644
index 0000000000000..8ef1d5785c700
--- /dev/null
+++ b/clang/test/CIR/CodeGen/non-type-template-param.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+template <const int N>
+void template_foo() {
+  int a = N + 5;
+}
+
+// CIR: %[[INIT:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["a", init]
+// CIR: %[[CONST_1:.*]] = cir.const #cir.int<1> : !s32i
+// CIR: %[[CONST_2:.*]] = cir.const #cir.int<5> : !s32i
+// CIR: %[[ADD:.*]] = cir.binop(add, %[[CONST_1]], %[[CONST_2]]) nsw : !s32i
+// CIR: cir.store{{.*}} %[[ADD]], %[[INIT]] : !s32i, !cir.ptr<!s32i>
+
+// LLVM: %[[INIT:.*]] = alloca i32, i64 1, align 4
+// LLVM: store i32 6, ptr %[[INIT]], align 4
+
+// OGCG: %[[INIT:.*]] = alloca i32, align 4
+// OGCG: store i32 6, ptr %[[INIT]], align 4
+
+void foo() {
+  template_foo<1>();
+}