[clang] [CIR] Upstream support for string literals (PR #140796)

[Erich Keane via cfe-commits]

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@@ -26,6 +26,34 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
   CIRGenBuilderTy(mlir::MLIRContext &mlirContext, const CIRGenTypeCache &tc)
       : CIRBaseBuilderTy(mlirContext), typeCache(tc) {}
 
+  /// Get a cir::ConstArrayAttr for a string literal.
+  /// Note: This is different from what is returned by
+  /// mlir::Builder::getStringAttr() which is an mlir::StringAttr.
+  mlir::Attribute getString(llvm::StringRef str, mlir::Type eltTy,
+                            unsigned size) {
+    unsigned finalSize = size ? size : str.size();
+
+    size_t lastNonZeroPos = str.find_last_not_of('\0');
+    // If the string is full of null bytes, emit a #cir.zero rather than
+    // a #cir.const_array.
+    if (lastNonZeroPos == llvm::StringRef::npos) {
+      auto arrayTy = cir::ArrayType::get(eltTy, finalSize);
+      return cir::ZeroAttr::get(arrayTy);
+    }
+    // We emit trailing zeros only if there are multiple trailing zeros.
+    int trailingZerosNum = 0;
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erichkeane wrote:

This could probably end up being size_t in length with a big enough set of zeros, right?  It doesn't look like you try tomake it negative anywhere, so perhaps it should too be size_t?

https://github.com/llvm/llvm-project/pull/140796