[ELF/AArch64] Simplify AArch64 isRelRelative

[zatrazz]

Summary

This patch simplifies the isRelRelative for AArch64 to just handle the
cases where it is not relative, instead of list all the relocations
that is. It also adds more testing for shared objects creation.

This patch is based upon http://reviews.llvm.org/D18330

[• rafael]

ELF/Target.cpp

1235

A relocation being relative or not is not a property of the command line.

[zatrazz]

Indeed my first analysis was wrong (isRelRelative should not rely on
command configuration). This patch address it and add the missing
relRelative relocations I found on both bootstrap and running the
testsuite.

[• rafael]

LGTM.

Thanks.

[grimar]

test/ELF/aarch64-relative.s

24

If you change almost the whole testcase then I would ask you to fix formating here. That looks wierd now, too many spaces are in front I think.
That is a minor of course.

[• rafael]

BTW, I think R_AARCH64_ADR_GOT_PAGE should also be in the list.

It is OK if that is done as a followup patch.

ELF/Target.cpp

 bool AArch64TargetInfo::isTlsDescRel(unsigned Type) const {
   return Type == R_AARCH64_TLSDESC_ADR_PAGE21 ||
          Type == R_AARCH64_TLSDESC_LD64_LO12_NC ||
          Type == R_AARCH64_TLSDESC_ADD_LO12_NC ||
          Type == R_AARCH64_TLSDESC_CALL;
 }
 
 bool AArch64TargetInfo::isRelRelative(uint32_t Type) const {
-  return Type == R_AARCH64_PREL32 || Type == R_AARCH64_ADR_PREL_PG_HI21 ||
-         Type == R_AARCH64_LDST8_ABS_LO12_NC ||
-         Type == R_AARCH64_LDST32_ABS_LO12_NC ||
-         Type == R_AARCH64_LDST64_ABS_LO12_NC ||
-         Type == R_AARCH64_ADD_ABS_LO12_NC || Type == R_AARCH64_CALL26;
+  switch (Type) {
+  default:
+    return true;
+  case R_AARCH64_ABS64:
+  case R_AARCH64_ADR_GOT_PAGE:
+  case R_AARCH64_LD64_GOT_LO12_NC:
+    return !Config->Shared;
+  }
 }
 
 bool AArch64TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
   return Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
          Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC;
 }
 
 uint32_t AArch64TargetInfo::getDynRel(uint32_t Type) const {

test/ELF/aarch64-relative.s

 // REQUIRES: aarch64
 // RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-freebsd %s -o %t.o
 // RUN: ld.lld %t.o -o %t.so -shared
 // RUN: llvm-readobj -r %t.so | FileCheck %s
-        adrp    x8, .Lfoo
-        strb    w9, [x8, :lo12:.Lfoo]
-        ldr     w0, [x8, :lo12:.Lfoo]
-        ldr     x0, [x8, :lo12:.Lfoo]
-        add     x0, x0, :lo12:.Lfoo
-        bl      .Lfoo
 
+        adr     x8, .Lfoo                 // R_AARCH64_ADR_PREL_LO21
+        adrp    x8, .Lfoo                 // R_AARCH64_ADR_PREL_PG_HI21
+        strb    w9, [x8, :lo12:.Lfoo]     // R_AARCH64_LDST8_ABS_LO12_NC
+        ldr     h17, [x19, :lo12:.Lfoo]   // R_AARCH64_LDST16_ABS_LO12_NC
+        ldr     w0, [x8, :lo12:.Lfoo]     // R_AARCH64_LDST32_ABS_LO12_NC
+        ldr     x0, [x8, :lo12:.Lfoo]     // R_AARCH64_LDST64_ABS_LO12_NC
+        ldr     q20, [x19, #:lo12:.Lfoo]  // R_AARCH64_LDST128_ABS_LO12_NC
+        add     x0, x0, :lo12:.Lfoo       // R_AARCH64_ADD_ABS_LO12_NC
+        bl      .Lfoo                     // R_AARCH64_CALL26
+        b       .Lfoo                     // R_AARCH64_JUMP26
+        beq     .Lfoo                     // R_AARCH64_CONDBR19
+        adr     x1, .Lfoo                 // R_AARCH64_ADR_PREL_LO21
+        tbz     x1, 7, .Lfoo              // R_AARCH64_TSTBR14
         .data
         .Lfoo:
 
         .rodata
         .long .Lfoo - .
 
 // CHECK:      Relocations [
 // CHECK-NEXT: ]