Add R_HEX_B15_PCREL relocation

[sidneym]

Summary

Add B15_PCREL relocation support and test, presumes that https://reviews.llvm.org/D48235 has merged.

[ruiu]

LGTM with these fixes.

ELF/Arch/Hexagon.cpp

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[sidneym]

Update to sort relocs.

ELF/Arch/Hexagon.cpp

for (size_t Bit = 0; Bit != 32; ++Bit) {
     }
   }
   return Result;
 }
 
 RelExpr Hexagon::getRelExpr(RelType Type, const Symbol &S,
                             const uint8_t *Loc) const {
   switch (Type) {
+  case R_HEX_B15_PCREL:
   case R_HEX_B22_PCREL:
   case R_HEX_B22_PCREL_X:
   case R_HEX_B32_PCREL_X:
     return R_PC;
   default:
     return R_ABS;
   }
 }
 
 static void or32le(uint8_t *P, int32_t V) { write32le(P, read32le(P) | V); }
 
 void Hexagon::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
   switch (Type) {
   case R_HEX_NONE:
     break;
+  case R_HEX_B15_PCREL:
+    or32le(Loc, applyMask(0x00df20fe, Val >> 2));
+    break;
   case R_HEX_B22_PCREL:
     or32le(Loc, applyMask(0x1ff3ffe, Val >> 2));
     break;
   case R_HEX_B22_PCREL_X:
     or32le(Loc, applyMask(0x1ff3ffe, Val & 0x3f));
     break;
   case R_HEX_B32_PCREL_X:
     or32le(Loc, applyMask(0x0fff3fff, Val >> 6));
     break;
   default:
     error(getErrorLocation(Loc) + "unrecognized reloc " + toString(Type));
     break;
   }
 }
 
 TargetInfo *elf::getHexagonTargetInfo() {
   static Hexagon Target;
   return &Target;
 }

test/ELF/hexagon.s

 # REQUIRES: hexagon
 # RUN: llvm-mc -filetype=obj -triple=hexagon-unknown-elf %s -o %t
 # RUN: llvm-mc -filetype=obj -triple=hexagon-unknown-elf %S/Inputs/hexagon.s -o %t2
 # RUN: ld.lld %t2 %t  -o %t3
 # RUN: llvm-objdump -d  %t3 | FileCheck %s
 
+# R_HEX_B15_PCREL
+if (p0) jump:nt #_start
+# CHECK: if (p0) jump:nt 0x11000
+
 # R_HEX_B22_PCREL
 call #_start
 # CHECK: call 0x11000
 
 # R_HEX_B32_PCREL_X
 # R_HEX_B22_PCREL_X
 call ##_start
 # CHECK: immext(#4294967232)
 # CHECK: call 0x11000