[PPC64] Set the IRelative relocation type.

[sfertile]

Summary

Set the IRelative relocation type and add a test to verify.

Depends on https://reviews.llvm.org/D46876

[ruiu]

LGTM

ELF/Arch/PPC64.cpp

 static uint16_t applyPPCHighera(uint64_t V) { return (V + 0x8000) >> 32; }
 static uint16_t applyPPCHighest(uint64_t V) { return V >> 48; }
 static uint16_t applyPPCHighesta(uint64_t V) { return (V + 0x8000) >> 48; }
 
 PPC64::PPC64() {
   GotRel = R_PPC64_GLOB_DAT;
   PltRel = R_PPC64_JMP_SLOT;
   RelativeRel = R_PPC64_RELATIVE;
+  IRelativeRel = R_PPC64_IRELATIVE;
   GotEntrySize = 8;
   PltEntrySize = 4;
   GotPltEntrySize = 8;
   GotBaseSymInGotPlt = false;
   GotBaseSymOff = 0x8000;
   GotHeaderEntriesNum = 1;
   GotPltHeaderEntriesNum = 2;
   PltHeaderSize = 60;

test/ELF/ppc64-ifunc.s

 # REQUIRES: ppc
 
 # RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
 # RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %p/Inputs/shared-ppc64.s -o %t2.o
 # RUN: ld.lld -shared %t2.o -o %t2.so
 # RUN: ld.lld %t.o %t2.so -o %t
 # RUN: llvm-objdump -D %t | FileCheck %s
 # RUN: llvm-readelf -dynamic-table %t | FileCheck --check-prefix=DT %s
+# RUN: llvm-readelf -dyn-relocations %t | FileCheck --check-prefix=DYNREL %s
 
 # RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
 # RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %p/Inputs/shared-ppc64.s -o %t2.o
 # RUN: ld.lld -shared %t2.o -o %t2.so
 # RUN: ld.lld %t.o %t2.so -o %t
 # RUN: llvm-objdump -D %t | FileCheck %s
 # RUN: llvm-readelf -dynamic-table %t | FileCheck --check-prefix=DT %s
+# RUN: llvm-readelf -dyn-relocations %t | FileCheck --check-prefix=DYNREL %s
 
 # CHECK: Disassembly of section .text:
 
 # Tocbase    + (0 << 16) + 32560
 # 0x100280e0 +  0        + 32560 = 0x10030010 (.plt[2])
 # CHECK: __plt_foo:
 # CHECK-NEXT:     std 2, 24(1)
 # CHECK-NEXT:     addis 12, 2, 0

 # CHECK:       Disassembly of section .got:
 # CHECK-NEXT:    .got:
 # CHECK-NEXT:    100200e0
 
 # Check .plt address
 # DT_PLTGOT should point to the start of the .plt section.
 # DT: 0x0000000000000003 PLTGOT 0x10030000
 
+# Check that we emit the correct dynamic relocation type for an ifunc
+# DYNREL: 'PLT' relocation section at offset 0x{{[0-9]+}} contains 48 bytes:
+# 48 bytes --> 2 Elf64_Rela relocations
+# DYNREL-NEXT: Offset        Info           Type               Symbol's Value  Symbol's Name + Addend
+# DYNREL-NEXT: {{[0-9a-f]+}} {{[0-9a-f]+}}  R_PPC64_JMP_SLOT      {{0+}}            foo + 0
+# DYNREL-NEXT: {{[0-9a-f]+}} {{[0-9a-f]+}}  R_PPC64_IRELATIVE     10010028
+
+
     .text
     .abiversion 2
 
 .type ifunc STT_GNU_IFUNC
 .globl ifunc
 ifunc:
  nop