Move profiler symbol LTO export to cg_llvm

The GCC backend likely uses different symbols and may potentially not
even need us to explicitly tell it to export the symbols it needs.

Author: bjorn3

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -15,6 +15,7 @@ use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
 use rustc_errors::DiagCtxtHandle;
+use rustc_hir::attrs::SanitizerSet;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_session::config::{self, Lto};
@@ -42,6 +43,33 @@ fn prepare_lto(
         .map(|symbol| CString::new(symbol.to_owned()).unwrap())
         .collect::<Vec<CString>>();
 
+    if cgcx.regular_module_config.instrument_coverage
+        || cgcx.regular_module_config.pgo_gen.enabled()
+    {
+        // These are weak symbols that point to the profile version and the
+        // profile name, which need to be treated as exported so LTO doesn't nix
+        // them.
+        const PROFILER_WEAK_SYMBOLS: [&CStr; 2] =
+            [c"__llvm_profile_raw_version", c"__llvm_profile_filename"];
+
+        symbols_below_threshold.extend(PROFILER_WEAK_SYMBOLS.iter().map(|&sym| sym.to_owned()));
+    }
+
+    if cgcx.regular_module_config.sanitizer.contains(SanitizerSet::MEMORY) {
+        let mut msan_weak_symbols = Vec::new();
+
+        // Similar to profiling, preserve weak msan symbol during LTO.
+        if cgcx.regular_module_config.sanitizer_recover.contains(SanitizerSet::MEMORY) {
+            msan_weak_symbols.push(c"__msan_keep_going");
+        }
+
+        if cgcx.regular_module_config.sanitizer_memory_track_origins != 0 {
+            msan_weak_symbols.push(c"__msan_track_origins");
+        }
+
+        symbols_below_threshold.extend(msan_weak_symbols.into_iter().map(|sym| sym.to_owned()));
+    }
+
     // __llvm_profile_counter_bias is pulled in at link time by an undefined reference to
     // __llvm_profile_runtime, therefore we won't know until link time if this symbol
     // should have default visibility.

compiler/rustc_codegen_ssa/src/back/lto.rs

@@ -2,7 +2,6 @@ use std::ffi::CString;
 use std::sync::Arc;
 
 use rustc_data_structures::memmap::Mmap;
-use rustc_hir::attrs::SanitizerSet;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo, SymbolExportLevel};
 use rustc_middle::ty::TyCtxt;
@@ -116,31 +115,6 @@ pub(super) fn exported_symbols_for_lto(
         }
     }
 
-    if tcx.sess.instrument_coverage() || tcx.sess.opts.cg.profile_generate.enabled() {
-        // These are weak symbols that point to the profile version and the
-        // profile name, which need to be treated as exported so LTO doesn't nix
-        // them.
-        const PROFILER_WEAK_SYMBOLS: [&str; 2] =
-            ["__llvm_profile_raw_version", "__llvm_profile_filename"];
-
-        symbols_below_threshold.extend(PROFILER_WEAK_SYMBOLS.iter().map(|&sym| sym.to_owned()));
-    }
-
-    if tcx.sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::MEMORY) {
-        let mut msan_weak_symbols = Vec::new();
-
-        // Similar to profiling, preserve weak msan symbol during LTO.
-        if tcx.sess.opts.unstable_opts.sanitizer_recover.contains(SanitizerSet::MEMORY) {
-            msan_weak_symbols.push("__msan_keep_going");
-        }
-
-        if tcx.sess.opts.unstable_opts.sanitizer_memory_track_origins != 0 {
-            msan_weak_symbols.push("__msan_track_origins");
-        }
-
-        symbols_below_threshold.extend(msan_weak_symbols.into_iter().map(|sym| sym.to_owned()));
-    }
-
     symbols_below_threshold
 }