From a6f7596fb9dd6790b237f6a628d6af8d80930bdb Mon Sep 17 00:00:00 2001
From: DianQK <dianqk@dianqk.net>
Date: Sat, 19 Aug 2023 16:10:49 +0800
Subject: 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.
---
 compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 104 ++++++++++++++++++++++-
 1 file changed, 103 insertions(+), 1 deletion(-)

(limited to 'compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp')

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
-- 
cgit 1.4.1-3-g733a5