Add `PreservedSymbols` from LLVM to LTO.

When building with LTO, builtin functions that are defined but whose calls have not been inserted yet, get internalized.
We need to prevent these symbols from being internalized at LTO time.

Refer to https://reviews.llvm.org/D49434.

1 files changed, 103 insertions, 1 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index ff2ec388a5f..f338b914c67 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -1120,6 +1120,102 @@ extern "C" void LLVMRustPrintPasses() {
   PB.printPassNames(outs());
 }
 
+// from https://github.com/llvm/llvm-project/blob/7021182d6b43de9488ab70de626192ce70b3a4a6/llvm/lib/Object/IRSymtab.cpp#L48-L57
+static const char *PreservedLibcallSymbols[] = {
+#define HANDLE_LIBCALL(code, name) name,
+#include "llvm/IR/RuntimeLibcalls.def"
+#undef HANDLE_LIBCALL
+  // RuntimeLibcalls.def missing symbols.
+  "__ctzsi2",
+  "__ctzdi2",
+  "__ctzti2",
+  "__ffssi2",
+  "__ffsdi2",
+  "__ffsti2",
+  "__paritysi2",
+  "__paritydi2",
+  "__parityti2",
+  "__popcountsi2",
+  "__popcountdi2",
+  "__popcountti2",
+  "__bswapsi2",
+  "__bswapdi2",
+  "__negti2",
+  "__udivmoddi4",
+  "__udivmodti4",
+  "__udivmodsi4",
+  "__divmodsi4",
+  "__divmoddi4",
+  "__divmodti4",
+  "__absvsi2",
+  "__absvdi2",
+  "__absvti2",
+  "__negvsi2",
+  "__negvdi2",
+  "__negvti2",
+  "__addvsi3",
+  "__addvdi3",
+  "__addvti3",
+  "__subvsi3",
+  "__subvdi3",
+  "__subvti3",
+  "__mulvsi3",
+  "__mulvdi3",
+  "__mulvti3",
+  "__cmpdi2",
+  "__cmpti2",
+  "__ucmpdi2",
+  "__ucmpti2",
+  "__mulsc3",
+  "__muldc3",
+  "__mulxc3",
+  "__multc3",
+  "__divsc3",
+  "__divdc3",
+  "__divxc3",
+  "__divtc3",
+  "__clear_cache",
+  "__enable_execute_stack",
+  "__gcc_personality_v0",
+  "__eprintf",
+  "__emutls_get_address",
+  "__trampoline_setup",
+  "__addsf3vfp",
+  "__adddf3vfp",
+  "__divsf3vfp",
+  "__divdf3vfp",
+  "__eqsf2vfp",
+  "__eqdf2vfp",
+  "__extendsfdf2vfp",
+  "__fixdfsivfp",
+  "__fixsfsivfp",
+  "__fixunssfsivfp",
+  "__fixunsdfsivfp",
+  "__floatsidfvfp",
+  "__floatsisfvfp",
+  "__floatunssidfvfp",
+  "__floatunssisfvfp",
+  "__gedf2vfp",
+  "__gesf2vfp",
+  "__gtdf2vfp",
+  "__gtsf2vfp",
+  "__ledf2vfp",
+  "__lesf2vfp",
+  "__ltdf2vfp",
+  "__ltsf2vfp",
+  "__muldf3vfp",
+  "__mulsf3vfp",
+  "__nedf2vfp",
+  "__negdf2vfp",
+  "__negsf2vfp",
+  "__negsf2vfp",
+  "__subdf3vfp",
+  "__subsf3vfp",
+  "__truncdfsf2vfp",
+  "__unorddf2vfp",
+  "__unordsf2vfp",
+};
+
 extern "C" void LLVMRustRunRestrictionPass(LLVMModuleRef M, char **Symbols,
                                            size_t Len) {
   auto PreserveFunctions = [=](const GlobalValue &GV) {
@@ -1135,7 +1231,7 @@ extern "C" void LLVMRustRunRestrictionPass(LLVMModuleRef M, char **Symbols,
         return true;
       }
     }
-    return false;
+    return llvm::is_contained(PreservedLibcallSymbols, GV.getName());
   };
 
   internalizeModule(*unwrap(M), PreserveFunctions);
@@ -1293,6 +1389,12 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
     auto GUID = GlobalValue::getGUID(preserved_symbols[i]);
     Ret->GUIDPreservedSymbols.insert(GUID);
   }
+  for (int i = 0; i < sizeof(PreservedLibcallSymbols) / sizeof(PreservedLibcallSymbols[0]); i++) {
+    if (auto *PreservedLibcallSymbol = PreservedLibcallSymbols[i]) {
+      auto GUID = GlobalValue::getGUID(PreservedLibcallSymbol);
+      Ret->GUIDPreservedSymbols.insert(GUID);
+    }
+  }
 
   // Collect the import/export lists for all modules from the call-graph in the
   // combined index