[PPC32] Emit R_PPC_PLTREL24 for calls to dso_local ifunc

  static void *ifunc(void) __attribute__((ifunc("resolver")));
  void foo() { ifunc(); }

The relocation produced by the ifunc() call:

1. gcc -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
2. gcc -msecure-plt -PIE => R_PPC_PLTREL24 r_addend=0x8000
3. clang -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
4. clang -msecure-plt -fPIE => R_PPC_REL24

4 is incorrect. The R_PPC_REL24 needs a call stub due to ifunc. If this
relocation is mixed with other R_PPC_PLTREL24(r_addend=0x8000) in a
function, both GNU ld and lld (after D71621 fix) may produce a wrong
result.

This patch fixes 4 to use R_PPC_PLTREL24, which matches GCC.
Both GNU ld and lld (after D71621) will be happy.

Reviewed By: sfertile

Differential Revision: https://reviews.llvm.org/D71649

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 3062dbb655f..ad7c9ea4e6c 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5102,9 +5102,10 @@ static SDValue transformCallee(const SDValue &Callee, SelectionDAG &DAG,
   auto isLocalCallee = [&]() {
     const GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
     const Module *Mod = DAG.getMachineFunction().getFunction().getParent();
+    const GlobalValue *GV = G ? G->getGlobal() : nullptr;
 
-    return DAG.getTarget().shouldAssumeDSOLocal(*Mod,
-                                                G ? G->getGlobal() : nullptr);
+    return DAG.getTarget().shouldAssumeDSOLocal(*Mod, GV) &&
+           !dyn_cast_or_null<GlobalIFunc>(GV);
   };
 
   // The PLT is only used in 32-bit ELF PIC mode.  Attempting to use the PLT in