[lld] r320286 - PPC32: Support R_PPC_PLTREL32 in static mode.

[Tim Northover via llvm-commits]

Author: tnorthover
Date: Sun Dec 10 00:42:34 2017
New Revision: 320286

URL: http://llvm.org/viewvc/llvm-project?rev=320286&view=rev
Log:
PPC32: Support R_PPC_PLTREL32 in static mode.

See https://reviews.llvm.org/D39226

Patch by vit9696 <vit9696 at avp.su>

Modified:
    lld/trunk/ELF/Arch/PPC.cpp
    lld/trunk/test/ELF/ppc-relocs.s

Modified: lld/trunk/ELF/Arch/PPC.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Arch/PPC.cpp?rev=320286&r1=320285&r2=320286&view=diff
==============================================================================
--- lld/trunk/ELF/Arch/PPC.cpp (original)
+++ lld/trunk/ELF/Arch/PPC.cpp Sun Dec 10 00:42:34 2017
@@ -34,6 +34,15 @@ RelExpr PPC::getRelExpr(RelType Type, co
   case R_PPC_REL24:
   case R_PPC_REL32:
     return R_PC;
+  // In general case R_PPC_PLTREL24 should result in R_PLT_PC, however, since
+  // PLT support is currently not available for PPC32 this workaround at least 
+  // allows lld to resolve local symbols when performing static linkage after
+  // LLVM started to forcibly use PLT relocations by default (see D38554).
+  // Non-local symbols will need a full PLT implementation, but once it lands
+  // local symbols should still avoid PLT table with static relocation model.
+  // This is the optimisation that bfd and gold are doing by default as well.
+  case R_PPC_PLTREL24:
+    return R_PC;
   default:
     return R_ABS;
   }
@@ -54,6 +63,7 @@ void PPC::relocateOne(uint8_t *Loc, RelT
   case R_PPC_REL32:
     write32be(Loc, Val);
     break;
+  case R_PPC_PLTREL24:
   case R_PPC_REL24:
     write32be(Loc, read32be(Loc) | (Val & 0x3FFFFFC));
     break;

Modified: lld/trunk/test/ELF/ppc-relocs.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/ppc-relocs.s?rev=320286&r1=320285&r2=320286&view=diff
==============================================================================
--- lld/trunk/test/ELF/ppc-relocs.s (original)
+++ lld/trunk/test/ELF/ppc-relocs.s Sun Dec 10 00:42:34 2017
@@ -76,3 +76,15 @@ mystr:
 # CHECK: Disassembly of section .R_PPC_ADDR32:
 # CHECK: .FR_PPC_ADDR32:
 # CHECK:    11024:       00 01 10 28
+
+.align  2
+.section .R_PPC_PLTREL24,"ax", at progbits
+.globl .R_PPC_PLTREL24
+.FR_PPC_PLTREL24:
+  b .Lfoox4 at PLT
+.section .R_PPC_PLTREL24_2,"ax", at progbits
+.Lfoox4:
+
+# CHECK: Disassembly of section .R_PPC_PLTREL24:
+# CHECK: .R_PPC_PLTREL24:
+# CHECK:    11028:       48 00 00 04     b .+4