[PowerPC] Only use PLT annotations if using PIC relocation model

Summary:
The default static (non-PIC, non-PIE) model for 32-bit powerpc does not
use @PLT annotations and relocations in GCC.  LLVM shouldn't use @PLT
annotations either, because it breaks secure-PLT linking with (some
versions of?) GNU LD.

Update the available-externally.ll test to reflect that default mode should be
the same as the static relocation, by using the same check prefix.

Reviewed by:    sfertile
Differential Revision: https://reviews.llvm.org/D70570

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 899a4f6f846..3062dbb655f 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5107,7 +5107,13 @@ static SDValue transformCallee(const SDValue &Callee, SelectionDAG &DAG,
                                                 G ? G->getGlobal() : nullptr);
   };
 
-  bool UsePlt = Subtarget.is32BitELFABI() && !isLocalCallee();
+  // The PLT is only used in 32-bit ELF PIC mode.  Attempting to use the PLT in
+  // a static relocation model causes some versions of GNU LD (2.17.50, at
+  // least) to force BSS-PLT, instead of secure-PLT, even if all objects are
+  // built with secure-PLT.
+  bool UsePlt =
+      Subtarget.is32BitELFABI() && !isLocalCallee() &&
+      Subtarget.getTargetMachine().getRelocationModel() == Reloc::PIC_;
 
   if (isFunctionGlobalAddress(Callee)) {
     const GlobalAddressSDNode *G = cast<GlobalAddressSDNode>(Callee);