[PATCH] D81948: [LLD][PowerPC] Add support for R_PPC64_GOT_PCREL34

[Stefan Pintilie via Phabricator via llvm-commits]

stefanp created this revision.
stefanp added reviewers: nemanjai, sfertile, MaskRay, ruiu, hfinkel, PowerPC.
Herald added subscribers: shchenz, kbarton, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

Add support for the 34bit relocation R_PPC64_GOT_PCREL34 for PC Relative in LLD.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81948

Files:
  lld/ELF/Arch/PPC64.cpp
  lld/test/ELF/ppc64-got-pcrel34-reloc.s


Index: lld/test/ELF/ppc64-got-pcrel34-reloc.s
===================================================================
--- /dev/null
+++ lld/test/ELF/ppc64-got-pcrel34-reloc.s
@@ -0,0 +1,48 @@
+# REQUIRES: ppc
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64le %s -o %t.o
+# RUN: ld.lld --shared %t.o -o %t
+# RUN: llvm-readelf -s %t | FileCheck %s --check-prefix=SYMBOL
+# RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=RELA
+# RUN: llvm-objdump -d --no-show-raw-insn --mcpu=future %t | FileCheck %s
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64 %s -o %t.o
+# RUN: ld.lld --shared %t.o -o %t
+# RUN: llvm-readelf -s %t | FileCheck %s --check-prefix=SYMBOL
+# RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=RELA
+# RUN: llvm-objdump -d --no-show-raw-insn --mcpu=future %t | FileCheck %s
+
+.text
+.globl	_start
+_start:
+# CHECK-LABEL: Disassembly of section .GLOB_INT_PCREL
+# CHECK:       10340:        pld 3, 565808(0), 1
+# CHECK:       10348:        lwa 3, 0(3)
+# SYMBOL:      00000000     0 NOTYPE  GLOBAL  DEFAULT     UND glob_int
+# RELA:        0009a570  0000000100000014 R_PPC64_GLOB_DAT       0000000000000000 glob_int + 0
+.section .GLOB_INT_PCREL,"ax", at progbits
+	pld 3, glob_int at got@PCREL(0), 1
+        lwa 3, 0(3)
+	blr
+
+# CHECK-LABEL: Disassembly of section .GLOB_INT_PCREL_OFFSET
+# CHECK:       10380:        pld 3, 565752(0), 1
+# CHECK:       10388:        lwa 3, 8(3)
+# SYMBOL:      00000000     0 NOTYPE  GLOBAL  DEFAULT     UND glob_int8
+# RELA:        0009a578  0000000200000014 R_PPC64_GLOB_DAT       0000000000000000 glob_int8 + 0
+.section .GLOB_INT_PCREL_OFFSET,"ax", at progbits
+	pld 3, glob_int8 at got@PCREL(0), 1
+        lwa 3, 8(3)
+	blr
+
+
+# CHECK-LABEL: Disassembly of section .GLOB_INT_PCREL_BIGOFFSET
+# CHECK:       8a4c0:        pld 3, 65728(0), 1
+# CHECK:       8a4c8:        lwa 3, 64(3)
+# SYMBOL:      00000000     0 NOTYPE  GLOBAL  DEFAULT     UND glob_int8_big
+# RELA:        0009a580  0000000300000014 R_PPC64_GLOB_DAT       0000000000000000 glob_int8_big + 0
+.space 500000
+.section .GLOB_INT_PCREL_BIGOFFSET,"ax", at progbits
+	pld 3, glob_int8_big at got@PCREL(0), 1
+        lwa 3, 64(3)
+	blr
Index: lld/ELF/Arch/PPC64.cpp
===================================================================
--- lld/ELF/Arch/PPC64.cpp
+++ lld/ELF/Arch/PPC64.cpp
@@ -670,6 +670,8 @@
   case R_PPC64_TOC16_HI:
   case R_PPC64_TOC16_LO:
     return R_GOTREL;
+  case R_PPC64_GOT_PCREL34:
+    return R_GOT_PC;
   case R_PPC64_TOC16_HA:
   case R_PPC64_TOC16_LO_DS:
     return config->tocOptimize ? R_PPC64_RELAX_TOC : R_GOTREL;
@@ -1013,6 +1015,19 @@
     writePrefixedInstruction(loc, instr | si0 | si1);
     break;
   }
+  case R_PPC64_GOT_PCREL34: {
+    uint64_t si0Mask = 0x00000003FFFF0000;
+    uint64_t si1Mask = 0x000000000000FFFF;
+    uint64_t fullMask = 0x0003FFFF0000FFFF;
+    checkInt(loc, val, 34, rel);
+
+    uint64_t si0 = (val & si0Mask) << 16;
+    uint64_t si1 = (val & si1Mask);
+    uint64_t instr = readPrefixedInstruction(loc) & ~fullMask;
+
+    writePrefixedInstruction(loc, instr | si0 | si1);
+    break;
+  }
   default:
     llvm_unreachable("unknown relocation");
   }


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