[ThinLTO] Add an API to trigger file-based API for returning objects to the linker

Summary:
The motivation is to support better the -object_path_lto option on
Darwin. The linker needs to write down the generate object files on
disk for later use by lldb or dsymutil (debug info are not present
in the final binary). We're moving this into libLTO so that we can
be smarter when a cache is enabled and hard-link when possible
instead of duplicating the files.

Reviewers: tejohnson, deadalnix, pcc

Subscribers: dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D27507

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289631 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 35 insertions, 1 deletions

diff --git a/include/llvm-c/lto.h b/include/llvm-c/lto.h
index ffdf5561dcf..c3af74cdeda 100644
--- a/include/llvm-c/lto.h
+++ b/include/llvm-c/lto.h
@@ -44,7 +44,7 @@ typedef bool lto_bool_t;
  * @{
  */
 
-#define LTO_API_VERSION 20
+#define LTO_API_VERSION 21
 
 /**
  * \since prior to LTO_API_VERSION=3
@@ -637,6 +637,29 @@ extern LTOObjectBuffer thinlto_module_get_object(thinlto_code_gen_t cg,
                                                  unsigned int index);
 
 /**
+ * Returns the number of object files produced by the ThinLTO CodeGenerator.
+ *
+ * It usually matches the number of input files, but this is not a guarantee of
+ * the API and may change in future implementation, so the client should not
+ * assume it.
+ *
+ * \since LTO_API_VERSION=21
+ */
+unsigned int thinlto_module_get_num_object_files(thinlto_code_gen_t cg);
+
+/**
+ * Returns the path to the ith object file produced by the ThinLTO
+ * CodeGenerator.
+ *
+ * Client should use \p thinlto_module_get_num_object_files() to get the number
+ * of available objects.
+ *
+ * \since LTO_API_VERSION=21
+ */
+const char *thinlto_module_get_object_file(thinlto_code_gen_t cg,
+                                           unsigned int index);
+
+/**
  * Sets which PIC code model to generate.
  * Returns true on error (check lto_get_error_message() for details).
  *
@@ -725,6 +748,17 @@ extern void thinlto_codegen_set_savetemps_dir(thinlto_code_gen_t cg,
                                               const char *save_temps_dir);
 
 /**
+ * Set the path to a directory where to save generated object files. This
+ * path can be used by a linker to request on-disk files instead of in-memory
+ * buffers. When set, results are available through
+ * thinlto_module_get_object_file() instead of thinlto_module_get_object().
+ *
+ * \since LTO_API_VERSION=21
+ */
+void thinlto_set_generated_objects_dir(thinlto_code_gen_t cg,
+                                       const char *save_temps_dir);
+
+/**
  * Sets the cpu to generate code for.
  *
  * \since LTO_API_VERSION=18