[CIR] Handle global string literals as char array initializer

This change adds the line of code needed to handle a string literal as an
initializer for a character array.

Author: andykaylor

clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp

@@ -254,8 +254,8 @@ class ConstExprEmitter
   }
 
   mlir::Attribute VisitStringLiteral(StringLiteral *e, QualType t) {
-    cgm.errorNYI(e->getBeginLoc(), "ConstExprEmitter::VisitStringLiteral");
-    return {};
+    // This is a string literal initializing an array in an initializer.
+    return cgm.getConstantArrayFromStringLiteral(e);
   }
 
   mlir::Attribute VisitObjCEncodeExpr(ObjCEncodeExpr *e, QualType t) {

clang/test/CIR/CodeGen/string-literals.c

@@ -5,6 +5,10 @@
 // RUN: %clang_cc1 -triple aarch64-none-linux-android21 -emit-llvm %s -o %t.ll
 // RUN: FileCheck --check-prefix=OGCG --input-file=%t.ll %s
 
+char g_str[] = "1234";
+
+// CIR: cir.global external @g_str = #cir.const_array<"1234\00" : !cir.array<!s8i x 5>> : !cir.array<!s8i x 5>
+
 // CIR: cir.global "private" cir_private dsolocal @[[STR1_GLOBAL:.*]] = #cir.const_array<"1\00" : !cir.array<!s8i x 2>> : !cir.array<!s8i x 2>
 // CIR: cir.global "private" cir_private dsolocal @[[STR2_GLOBAL:.*]] = #cir.zero : !cir.array<!s8i x 1>
 // CIR: cir.global "private" cir_private dsolocal @[[STR3_GLOBAL:.*]] = #cir.zero : !cir.array<!s8i x 2>