[clang] [llvm] [clang-tools-extra] [flang] [flang] Add EXECUTE_COMMAND_LINE runtime and lowering intrinsics implementation (PR #74077)

[Yi Wu via cfe-commits]

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@@ -411,6 +412,48 @@ RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from,
     bool toIsContiguous, bool fromIsContiguous);
 RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from);
 
+RT_API_ATTRS const char *EnsureNullTerminated(
+    const char *str, size_t length, Terminator &terminator);
+
+RT_API_ATTRS std::size_t LengthWithoutTrailingSpaces(const Descriptor &d);
+
+// Returns the length of the \p string. Assumes \p string is valid.
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yi-wu-arm wrote:

moved back to `command.cpp` since it is only used there.

https://github.com/llvm/llvm-project/pull/74077