ELF: Set sh_info on RelaIplt to point to the IgotPlt output section.

[pcc]

Summary

Previously we were setting it to the GotPlt output section, which is
incorrect on ARM where this section is in .got. In static binaries
this can lead to sh_link being set to -1 (because there is no .got.plt)
which results in various tools rejecting the output file.

[peter.smith]

Looks good to me. Thanks for the fix.

ELF/SyntheticSections.cpp

void RelocationBaseSection::finalizeContents() {
   // relocations due to IFUNC (e.g. strcpy). sh_link will be set to 0 in that
   // case.
   InputSection *SymTab = Config->Relocatable ? In.SymTab : In.DynSymTab;
   if (SymTab && SymTab->getParent())
     getParent()->Link = SymTab->getParent()->SectionIndex;
   else
     getParent()->Link = 0;
 
-  if (In.RelaIplt == this || In.RelaPlt == this)
+  if (In.RelaPlt == this)
     getParent()->Info = In.GotPlt->getParent()->SectionIndex;
+  if (In.RelaIplt == this)
+    getParent()->Info = In.IgotPlt->getParent()->SectionIndex;
 }
 
 RelrBaseSection::RelrBaseSection()
     : SyntheticSection(SHF_ALLOC,
                        Config->UseAndroidRelrTags ? SHT_ANDROID_RELR : SHT_RELR,
                        Config->Wordsize, ".relr.dyn") {}
 
 template <class ELFT>

test/ELF/arm-gnu-ifunc.s

 // CHECK:          Name: .rel.dyn
 // CHECK-NEXT:     Type: SHT_REL
 // CHECK-NEXT:     Flags [
 // CHECK-NEXT:       SHF_ALLOC
 // CHECK-NEXT:     ]
 // CHECK-NEXT:     Address: 0x100F4
 // CHECK-NEXT:     Offset: 0xF4
 // CHECK-NEXT:     Size: 16
+// CHECK-NEXT:     Link:
+// CHECK-NEXT:     Info: 4
 // CHECK:          Name: .plt
 // CHECK-NEXT:     Type: SHT_PROGBITS
 // CHECK-NEXT:     Flags [
 // CHECK-NEXT:       SHF_ALLOC
 // CHECK-NEXT:       SHF_EXECINSTR
 // CHECK-NEXT:     ]
 // CHECK-NEXT:     Address: 0x11020
 // CHECK-NEXT:     Offset: 0x1020
 // CHECK-NEXT:     Size: 32
-// CHECK:          Name: .got
+// CHECK:          Index: 4
+// CHECK-NEXT:     Name: .got
 // CHECK-NEXT:     Type: SHT_PROGBITS
 // CHECK-NEXT:     Flags [
 // CHECK-NEXT:       SHF_ALLOC
 // CHECK-NEXT:       SHF_WRITE
 // CHECK-NEXT:     ]
 // CHECK-NEXT:     Address: 0x12000
 // CHECK-NEXT:     Offset: 0x2000
 // CHECK-NEXT:     Size: 8