[CIR] Implement PackIndexingExpr for ScalarExpr (#1719)

Implement PackIndexingExpr for ScalarExpr

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -153,6 +153,11 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
 
   mlir::Value VisitConstantExpr(ConstantExpr *E) { llvm_unreachable("NYI"); }
   mlir::Value VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr()); }
+
+  mlir::Value VisitPackIndexingExpr(PackIndexingExpr *E) {
+    return Visit(E->getSelectedExpr());
+  }
+
   mlir::Value
   VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
     return Visit(E->getReplacement());

clang/test/CIR/CodeGen/pack-indexing.cpp

@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++2c -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 -std=c++2c -fclangir -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=LLVM
+
+int pack_indexing(auto... p) { return p...[0]; }
+
+// CIR: %[[P_0:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["p", init]
+// CIR: %[[P_1:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["p", init]
+// CIR: %[[P_2:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["p", init]
+// CIR: %[[RET_VAL:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["__retval"]
+// CIR: %[[RESULT:.*]] = cir.load{{.*}} %[[P_0]] : !cir.ptr<!s32i>, !s32i
+// CIR: cir.store %[[RESULT]], %[[RET_VAL]] : !s32i, !cir.ptr<!s32i>
+// CIR: %[[TMP:.*]] = cir.load %[[RET_VAL]] : !cir.ptr<!s32i>, !s32i
+// CIR: cir.return %[[TMP]] : !s32i
+
+// LLVM: %[[P_0:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[P_1:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[P_2:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[RET_VAL:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[RESULT:.*]] = load i32, ptr %[[P_0]], align 4
+// LLVM: store i32 %[[RESULT]], ptr %[[RET_VAL]], align 4
+// LLVM: %[[TMP:.*]] = load i32, ptr %[[RET_VAL]], align 4
+// LLVM: ret i32 %[[TMP]]
+
+int foo() { return pack_indexing(1, 2, 3); }
+
+// CIR: %[[RET_VAL:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["__retval"]
+// CIR: %[[RESULT:.*]] = cir.call @_Z13pack_indexingIJiiiEEiDpT_({{.*}}, {{.*}}, {{.*}}) : (!s32i, !s32i, !s32i) -> !s32i
+// CIR: cir.store %[[RESULT]], %[[RET_VAL]] : !s32i, !cir.ptr<!s32i>
+// CIR: %[[TMP:.*]] = cir.load %[[RET_VAL]] : !cir.ptr<!s32i>, !s32i
+// CIR: cir.return %[[TMP]] : !s32i
+
+// LLVM: %[[RET_VAL:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[RESULT:.*]] = call i32 @_Z13pack_indexingIJiiiEEiDpT_(i32 1, i32 2, i32 3)
+// LLVM: store i32 %[[RESULT]], ptr %[[RET_VAL]], align 4
+// LLVM: %[[TMP:.*]] = load i32, ptr %[[RET_VAL]], align 4
+// LLVM: ret i32 %[[TMP]]