Support shared objects for split stack.

1 files changed, 13 insertions, 9 deletions

diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 48603a30e6a..801e2f86867 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -928,9 +928,8 @@ void InputSectionBase::adjustSplitStackFunctionPrologues(uint8_t *Buf,
       continue;
 
     // Ignore calls into the split-stack api.
-    Defined *D = cast<Defined>(Rel.Sym);
-    if (D->getName().startswith("__morestack")) {
-      if (D->getName().equals("__morestack"))
+    if (Rel.Sym->getName().startswith("__morestack")) {
+      if (Rel.Sym->getName().equals("__morestack"))
         MorestackCalls.push_back(&Rel);
       continue;
     }
@@ -938,13 +937,18 @@ void InputSectionBase::adjustSplitStackFunctionPrologues(uint8_t *Buf,
     // A relocation to non-function isn't relevant. Sometimes
     // __morestack is not marked as a function, so this check comes
     // after the name check.
-    if (D->Type != STT_FUNC)
+    if (Rel.Sym->Type != STT_FUNC)
       continue;
 
-    // If the callee's-file was compiled with split stack, nothing to do.
-    auto *IS = cast_or_null<InputSection>(D->Section);
-    if (!IS || IS->getFile<ELFT>()->SplitStack)
-      continue;
+    // If the callee's-file was compiled with split stack, nothing to do.  In
+    // this context, a "Defined" symbol is one "defined by the binary currently
+    // being produced". So an "undefined" symbol might be provided by a shared
+    // library. It is not possible to tell how such symbols were compiled, so be
+    // conservative.
+    if (Defined *D = dyn_cast<Defined>(Rel.Sym))
+      if (InputSection *IS = cast_or_null<InputSection>(D->Section))
+        if (!IS || IS->getFile<ELFT>()->SplitStack)
+          continue;
 
     if (enclosingPrologueAttempted(Rel.Offset, Prologues))
       continue;
@@ -956,7 +960,7 @@ void InputSectionBase::adjustSplitStackFunctionPrologues(uint8_t *Buf,
         continue;
       if (!getFile<ELFT>()->SomeNoSplitStack)
         error(lld::toString(this) + ": " + F->getName() +
-              " (with -fsplit-stack) calls " + D->getName() +
+              " (with -fsplit-stack) calls " + Rel.Sym->getName() +
               " (without -fsplit-stack), but couldn't adjust its prologue");
     }
   }