[Mips] Implement R_MIPS_PC18_S3 relocation handling

llvm-svn: 232756

lld/lib/ReaderWriter/ELF/Mips/MipsRelocationHandler.cpp

@@ -65,6 +65,8 @@ static MipsRelocationParams getRelocationParams(uint32_t rType) {
   case R_MIPS_26:
   case LLD_R_MIPS_GLOBAL_26:
     return {4, 0x3ffffff, 2, false};
+  case R_MIPS_PC18_S3:
+    return {4, 0x3ffff, 3, false};
   case R_MIPS_PC19_S2:
     return {4, 0x7ffff, 2, false};
   case R_MIPS_PC21_S2:
@@ -225,6 +227,14 @@ static uint32_t relocGPRel32(uint64_t S, int64_t A, uint64_t GP) {
   return result;
 }
 
+/// \brief R_MIPS_PC18_S3
+static uint32_t relocPc18(uint64_t P, uint64_t S, int64_t A) {
+  A = llvm::SignExtend32<21>(A);
+  // FIXME (simon): Check that S + A has 8-byte alignment
+  int32_t result = S + A - ((P | 7) ^ 7); // pc with cleared 3-lsb
+  return result >> 3;
+}
+
 /// \brief R_MIPS_PC19_S2
 static uint32_t relocPc19(uint64_t P, uint64_t S, int64_t A) {
   A = llvm::SignExtend32<21>(A);
@@ -381,6 +391,8 @@ static ErrorOr<uint64_t> calculateRelocation(const Reference &ref,
     return relocGOT(tgtAddr, gpAddr);
   case R_MIPS_GOT_OFST:
     return relocGOTOfst(tgtAddr, ref.addend());
+  case R_MIPS_PC18_S3:
+    return relocPc18(relAddr, tgtAddr, ref.addend());
   case R_MIPS_PC19_S2:
     return relocPc19(relAddr, tgtAddr, ref.addend());
   case R_MIPS_PC21_S2:

lld/test/elf/Mips/rel-pc18-s3.test

@@ -0,0 +1,54 @@
+# Check handling of R_MIPS_PC18_S3 relocation.
+
+# RUN: yaml2obj -format=elf %s > %t.o
+# RUN: lld -flavor gnu -target mipsel -e T0 -o %t.exe %t.o
+# RUN: llvm-objdump -s -t %t.exe | FileCheck %s
+
+# CHECK: Contents of section .text:
+# CHECK-NEXT: 400110 00000000 01000000 00000000 00000000
+#                             ^ V
+#                               A = -1 << 3 = -8 =>
+#                               V = (T1 - 8 - (T0|7)^7) >> 3 =>
+#                               V => 8 >> 3 = 1
+
+# CHECK: SYMBOL TABLE:
+# CHECK: 00400110 g  F .text  00000010 T0
+# CHECK: 00400120 g  F .text  00000004 T1
+
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_MIPS
+  Flags:   [EF_MIPS_CPIC, EF_MIPS_ABI_O32, EF_MIPS_ARCH_32R6]
+
+Sections:
+- Name:         .text
+  Type:         SHT_PROGBITS
+  Content:      "00000000ffff0300000000000000000000000000"
+#                                                ^ T1
+#                ^ T0    ^ A := 0x3ffff == -1
+  AddressAlign: 16
+  Flags:        [ SHF_ALLOC, SHF_EXECINSTR ]
+
+- Name:         .rel.text
+  Type:         SHT_REL
+  Info:         .text
+  AddressAlign: 4
+  Relocations:
+    - Offset: 4
+      Symbol: T1
+      Type:   R_MIPS_PC18_S3
+
+Symbols:
+  Global:
+    - Name:    T0
+      Section: .text
+      Type:    STT_FUNC
+      Value:   0
+      Size:    16
+    - Name:    T1
+      Section: .text
+      Type:    STT_FUNC
+      Value:   16
+      Size:    4