[ARM] GlobalISel: Select globals in PIC mode

Support the selection of G_GLOBAL_VALUE in the PIC relocation model. For
simplicity we use the same pseudoinstructions for both Darwin and ELF:
(MOV|LDRLIT)_ga_pcrel(_ldr).

This is new for ELF, so it requires a small update to the ARM pseudo
expansion pass to make sure it adds the correct constant pool modifier
and add-current-address in the case of ELF.

Differential Revision: https://reviews.llvm.org/D36507

llvm-svn: 311992

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp b/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp
index 1a5b7d273aa..18fd077c2bd 100644
--- a/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp
@@ -1308,9 +1308,11 @@ bool ARMExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
 
       if (IsPIC) {
         unsigned PCAdj = IsARM ? 8 : 4;
+        auto Modifier = STI->getCPModifier(GV);
         ARMPCLabelIndex = AFI->createPICLabelUId();
-        CPV = ARMConstantPoolConstant::Create(GV, ARMPCLabelIndex,
-                                              ARMCP::CPValue, PCAdj);
+        CPV = ARMConstantPoolConstant::Create(
+            GV, ARMPCLabelIndex, ARMCP::CPValue, PCAdj, Modifier,
+            /*AddCurrentAddr*/ Modifier == ARMCP::GOT_PREL);
       } else
         CPV = ARMConstantPoolConstant::Create(GV, ARMCP::no_modifier);