[PATCH] D102985: [lld][ELF][SPARC] Fix GOT-relative relocations

[LemonBoy via Phabricator via llvm-commits]

LemonBoy created this revision.
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SPARC V9 requires all the relocation entries to be of type RELA, teach lld about this.
Support `R_SPARC_GOT13` relocation, completing the support for 32bit PIC model.
Reserve a GOT entry as required by the ABI.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D102985

Files:
  lld/ELF/Arch/SPARCV9.cpp
  lld/ELF/Driver.cpp
  lld/test/ELF/sparcv9-reloc-got.s


Index: lld/test/ELF/sparcv9-reloc-got.s
===================================================================
--- /dev/null
+++ lld/test/ELF/sparcv9-reloc-got.s
@@ -0,0 +1,24 @@
+# REQUIRES: sparc
+# RUN: llvm-mc -filetype=obj -triple=sparcv9 %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t.so
+# RUN: llvm-objdump -d --no-show-raw-insn %t.so | FileCheck %s
+# RUN: llvm-readobj -r %t.so | FileCheck --check-prefix=RELOC %s
+
+# 13-bit PIC
+
+# CHECK: ldx [%l7+8], %o0
+ldx [%l7 + %got13(x)], %o0
+
+# 32-bit PIC
+
+# CHECK-NEXT: sethi 0, %o1
+# CHECK-NEXT: add %o1, 16, %o1
+# CHECK-NEXT: ldx [%l7+%o1], %o0
+sethi %got22(y), %o1
+add %o1, %got10(y), %o1
+ldx [%l7 + %o1], %o0
+
+# RELOC: .rela.dyn {
+# RELOC-NEXT: R_SPARC_GLOB_DAT x 0x0
+# RELOC-NEXT: R_SPARC_GLOB_DAT y 0x0
+# RELOC-NEXT: }
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -926,7 +926,7 @@
   // Otherwise use the psABI defined relocation entry format.
   uint16_t m = config->emachine;
   return m == EM_AARCH64 || m == EM_AMDGPU || m == EM_HEXAGON || m == EM_PPC ||
-         m == EM_PPC64 || m == EM_RISCV || m == EM_X86_64;
+         m == EM_PPC64 || m == EM_RISCV || m == EM_SPARCV9 || m == EM_X86_64;
 }
 
 static void parseClangOption(StringRef opt, const Twine &msg) {
Index: lld/ELF/Arch/SPARCV9.cpp
===================================================================
--- lld/ELF/Arch/SPARCV9.cpp
+++ lld/ELF/Arch/SPARCV9.cpp
@@ -25,6 +25,7 @@
   SPARCV9();
   RelExpr getRelExpr(RelType type, const Symbol &s,
                      const uint8_t *loc) const override;
+  void writeGotHeader(uint8_t *buf) const override;
   void writePlt(uint8_t *buf, const Symbol &sym,
                 uint64_t pltEntryAddr) const override;
   void relocate(uint8_t *loc, const Relocation &rel,
@@ -45,6 +46,14 @@
   defaultCommonPageSize = 8192;
   defaultMaxPageSize = 0x100000;
   defaultImageBase = 0x100000;
+
+  // .got[0] = _DYNAMIC
+  gotBaseSymInGotPlt = false;
+  gotHeaderEntriesNum = 1;
+}
+
+void SPARCV9::writeGotHeader(uint8_t *buf) const {
+  write32(buf, mainPart->dynamic->getVA());
 }
 
 RelExpr SPARCV9::getRelExpr(RelType type, const Symbol &s,
@@ -69,7 +78,7 @@
   case R_SPARC_WDISP30:
     return R_PC;
   case R_SPARC_GOT10:
-    return R_GOT_OFF;
+  case R_SPARC_GOT13:
   case R_SPARC_GOT22:
     return R_GOT_OFF;
   case R_SPARC_WPLT30:
@@ -127,6 +136,11 @@
     checkInt(loc, val, 21, rel);
     write32be(loc, (read32be(loc) & ~0x0007ffff) | ((val >> 2) & 0x0007ffff));
     break;
+  case R_SPARC_GOT13:
+    // V-simm13
+    checkInt(loc, val, 13, rel);
+    write32be(loc, (read32be(loc) & ~0x00001fff) | (val & 0x000003ff));
+    break;
   case R_SPARC_GOT10:
   case R_SPARC_PC10:
     // T-simm10


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