[PATCH] D59373: Make a hack for LTO work only when you are actually doing LTO.

[Rui Ueyama via Phabricator via llvm-commits]

ruiu created this revision.
ruiu added a reviewer: eli.friedman.
Herald added subscribers: arphaman, dexonsmith, steven_wu, MaskRay, arichardson, inglorion, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

We allow an archive file without symbol table as a linker input as a
workaround for a very common error in LTO build. But that logic worked
even for an archive file containing non-bitcode files, which is not
expected. This patch limits that workaround to one that contains only
bitcode files.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D59373

Files:
  lld/ELF/Driver.cpp
  lld/test/ELF/invalid/invalid-elf.test
  lld/test/ELF/lto/archive-no-index.ll


Index: lld/test/ELF/lto/archive-no-index.ll
===================================================================
--- lld/test/ELF/lto/archive-no-index.ll
+++ lld/test/ELF/lto/archive-no-index.ll
@@ -1,8 +1,6 @@
 ; REQUIRES: x86
-; Tests that we suggest that LTO symbols missing from an archive index
-; may be the cause of undefined references, but only if we both
-; encountered an empty archive index and undefined references (to prevent
-; noisy false alarms).
+; Tests that we accept an archive file without symbol table
+; if all the member files are bitcode files.
 
 ; RUN: llvm-as -o %t1.o %s
 ; RUN: llvm-as -o %t2.o %S/Inputs/archive.ll
@@ -23,3 +21,14 @@
   call void @f()
   ret i32 0
 }
+
+; RUN: echo 'f:' | llvm-mc -triple=x86_64-pc-linux -filetype=obj - -o %t3.o
+; RUN: rm -f %t3.a
+; RUN: llvm-ar crS %t3.a %t3.o
+; RUN: not ld.lld -o /dev/null -emain %t1.o %t3.a 2>&1 | FileCheck -check-prefix=ERR1 %s
+; ERR1: error: undefined symbol: f
+
+; RUN: rm -f %t4.a
+; RUN: llvm-ar cr %t4.a
+; RUN: not ld.lld -o /dev/null -emain %t1.o %t4.a 2>&1 | FileCheck -check-prefix=ERR2 %s
+; ERR2: error: undefined symbol: f
Index: lld/test/ELF/invalid/invalid-elf.test
===================================================================
--- lld/test/ELF/invalid/invalid-elf.test
+++ lld/test/ELF/invalid/invalid-elf.test
@@ -4,7 +4,7 @@
 # RUN: echo > %t/empty.o
 # RUN: llvm-ar --format=gnu cr %t/not-elf.a %t/empty.o
 
-# RUN: not ld.lld %t/simple.o %t/not-elf.a -o %t2 2>&1 | \
+# RUN: not ld.lld --whole-archive %t/not-elf.a -o %t2 2>&1 | \
 # RUN:   FileCheck --check-prefix=NOT-ELF %s
 # NOT-ELF: not-elf.a(empty.o): not an ELF file
 
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -213,7 +213,14 @@
     // understand the LLVM bitcode file. It is a pretty common error, so
     // we'll handle it as if it had a symbol table.
     if (!File->isEmpty() && !File->hasSymbolTable()) {
-      for (const auto &P : getArchiveMembers(MBRef))
+      // First, check if all members are bitcode files.
+      for (const std::pair<MemoryBufferRef, uint64_t> &P :
+           getArchiveMembers(MBRef))
+        if (identify_magic(P.first.getBuffer()) != file_magic::bitcode)
+          return;
+
+      for (const std::pair<MemoryBufferRef, uint64_t> &P :
+           getArchiveMembers(MBRef))
         Files.push_back(make<LazyObjFile>(P.first, Path, P.second));
       return;
     }


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