[PATCH] D118756: [ELF] Avoid wrapping unreferenced lazy symbols

[Shoaib Meenai via Phabricator via llvm-commits]

smeenai updated this revision to Diff 405861.
smeenai added a comment.

Address comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D118756/new/

https://reviews.llvm.org/D118756

Files:
  lld/ELF/Driver.cpp
  lld/test/ELF/wrap-lazy.test


Index: lld/test/ELF/wrap-lazy.test
===================================================================
--- /dev/null
+++ lld/test/ELF/wrap-lazy.test
@@ -0,0 +1,58 @@
+# REQUIRES: x86
+
+# RUN: split-file %s %t
+# RUN: llvm-as %t/lazy.ll -o %tlazybitcode.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-elf %t/dummy.s -o %tdummy.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-elf %t/lazy.s -o %tlazy.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-elf %t/ref.s -o %tref.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-elf %t/weakref.s -o %tweakref.o
+# RUN: ld.lld -shared -o %t1.so %tdummy.o --start-lib %tlazy.o --wrap lazy
+# RUN: llvm-readelf -s %t1.so | FileCheck --check-prefix=NO-LAZY %s
+# RUN: ld.lld -shared -o %t2.so %tdummy.o --start-lib %tlazybitcode.o --wrap lazy
+# RUN: llvm-readelf -s %t2.so | FileCheck --check-prefix=NO-LAZY %s
+# RUN: ld.lld -shared -o %t3.so %tdummy.o --start-lib %tlazy.o -u lazy --wrap lazy
+# RUN: llvm-readelf -s %t3.so | FileCheck --check-prefix=LAZY-DEF %s
+# RUN: ld.lld -shared -o %t4.so %tdummy.o %tlazy.o --wrap lazy
+# RUN: llvm-readelf -s %t4.so | FileCheck --check-prefix=LAZY-DEF %s
+# RUN: ld.lld -shared -o %t5.so %tref.o --start-lib %tlazy.o --wrap lazy
+# RUN: llvm-readelf -s %t5.so | FileCheck --check-prefix=LAZY-DEF %s
+# RUN: ld.lld -shared -o %t6.so %tweakref.o --start-lib %tlazy.o --wrap lazy
+# RUN: llvm-readelf -s %t6.so | FileCheck --check-prefix=LAZY-REF %s
+# RUN: ld.lld -shared -o %t7.so %tweakref.o --start-lib %tlazybitcode.o --wrap lazy
+# RUN: llvm-readelf -s %t7.so | FileCheck --check-prefix=LAZY-REF %s
+# RUN: ld.lld -shared -o %tweakref.so %tweakref.o
+# RUN: ld.lld -shared -o %t8.so %tdummy.o %tweakref.so --start-lib %tlazy.o --wrap lazy
+# RUN: llvm-readelf -s %t8.so | FileCheck --check-prefix=NO-LAZY %s
+
+# NO-LAZY-NOT: lazy
+# NO-LAZY-NOT: __wrap_lazy
+
+# LAZY-DEF-DAG: [[#]] lazy
+# LAZY-DEF-DAG: UND __wrap_lazy
+
+# LAZY-REF-DAG: UND lazy
+# LAZY-REF-DAG: UND __wrap_lazy
+
+#--- dummy.s
+.globl dummy
+dummy:
+	retq
+
+#--- lazy.ll
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-elf"
+define void @lazy() {
+  ret void
+}
+
+#--- lazy.s
+.globl lazy
+lazy:
+	retq
+
+#--- ref.s
+	jmp	lazy
+
+#--- weakref.s
+.weak lazy
+	jmp	lazy
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -2047,7 +2047,11 @@
       continue;
 
     Symbol *sym = symtab->find(name);
-    if (!sym)
+    // Avoid wrapping symbols that are lazy and unreferenced at this point, to
+    // not create undefined references. The isUsedInRegularObj check handles the
+    // case of a weak reference, which we still want to wrap even though it
+    // doesn't cause lazy symbols to be extracted.
+    if (!sym || (sym->isLazy() && !sym->isUsedInRegularObj))
       continue;
 
     Symbol *real = addUnusedUndefined(saver().save("__real_" + name));


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