[AMDGPU] Add 32-bit lo/hi got and pc relative variant kinds and emit appropriate relocations

[• tstellarAMD]

LGTM.

include/llvm/MC/MCExpr.h

enum VariantKind : uint16_t {
     VK_Hexagon_LD_GOT,
     VK_Hexagon_GD_PLT,
     VK_Hexagon_LD_PLT,
     VK_Hexagon_IE,
     VK_Hexagon_IE_GOT,
 
     VK_WebAssembly_FUNCTION, // Function table index, rather than virtual addr
 
+    VK_AMDGPU_GOTPCREL32_LO, // symbol@gotpcrel32@lo
+    VK_AMDGPU_GOTPCREL32_HI, // symbol@gotpcrel32@hi
+    VK_AMDGPU_REL32_LO,      // symbol@rel32@lo
+    VK_AMDGPU_REL32_HI,      // symbol@rel32@hi
+
     VK_TPREL,
     VK_DTPREL
   };
 
 private:
   /// The symbol reference modifier.
   const VariantKind Kind;
 

lib/MC/MCExpr.cpp

StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_Hexagon_GPREL: return "GPREL";
   case VK_Hexagon_GD_GOT: return "GDGOT";
   case VK_Hexagon_LD_GOT: return "LDGOT";
   case VK_Hexagon_GD_PLT: return "GDPLT";
   case VK_Hexagon_LD_PLT: return "LDPLT";
   case VK_Hexagon_IE: return "IE";
   case VK_Hexagon_IE_GOT: return "IEGOT";
   case VK_WebAssembly_FUNCTION: return "FUNCTION";
+  case VK_AMDGPU_GOTPCREL32_LO: return "gotpcrel32@lo";
+  case VK_AMDGPU_GOTPCREL32_HI: return "gotpcrel32@hi";
+  case VK_AMDGPU_REL32_LO: return "rel32@lo";
+  case VK_AMDGPU_REL32_HI: return "rel32@hi";
   }
   llvm_unreachable("Invalid variant kind");
 }
 
 MCSymbolRefExpr::VariantKind
 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
   return StringSwitch<VariantKind>(Name.lower())
     .Case("dtprel", VK_DTPREL)
return StringSwitch<VariantKind>(Name.lower())
     .Case("pcrel", VK_Hexagon_PCREL)
     .Case("none", VK_ARM_NONE)
     .Case("got_prel", VK_ARM_GOT_PREL)
     .Case("target1", VK_ARM_TARGET1)
     .Case("target2", VK_ARM_TARGET2)
     .Case("prel31", VK_ARM_PREL31)
     .Case("sbrel", VK_ARM_SBREL)
     .Case("tlsldo", VK_ARM_TLSLDO)
+    .Case("gotpcrel32@lo", VK_AMDGPU_GOTPCREL32_LO)
+    .Case("gotpcrel32@hi", VK_AMDGPU_GOTPCREL32_HI)
+    .Case("rel32@lo", VK_AMDGPU_REL32_LO)
+    .Case("rel32@hi", VK_AMDGPU_REL32_HI)
     .Default(VK_Invalid);
 }
 
 void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
   if (UseParensForSymbolVariant)
     OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
   else
     OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());

lib/Target/AMDGPU/MCTargetDesc/AMDGPUELFObjectWriter.cpp

if (SymA->getSymbol().getName() == "SCRATCH_RSRC_DWORD1")
       return ELF::R_AMDGPU_ABS32_HI;
   }
 
   switch (Target.getAccessVariant()) {
   default:
     break;
   case MCSymbolRefExpr::VK_GOTPCREL:
     return ELF::R_AMDGPU_GOTPCREL;
+  case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_LO:
+    return ELF::R_AMDGPU_GOTPCREL32_LO;
+  case MCSymbolRefExpr::VK_AMDGPU_GOTPCREL32_HI:
+    return ELF::R_AMDGPU_GOTPCREL32_HI;
+  case MCSymbolRefExpr::VK_AMDGPU_REL32_LO:
+    return ELF::R_AMDGPU_REL32_LO;
+  case MCSymbolRefExpr::VK_AMDGPU_REL32_HI:
+    return ELF::R_AMDGPU_REL32_HI;
   }
 
   switch (Fixup.getKind()) {
   default: break;
   case FK_PCRel_4:
     return ELF::R_AMDGPU_REL32;
   case FK_Data_4:
   case FK_SecRel_4:

test/MC/AMDGPU/reloc.s

 // RUN: llvm-mc -filetype=obj -triple amdgcn-- -mcpu=kaveri -show-encoding %s | llvm-readobj -relocations | FileCheck %s
 
 // CHECK: Relocations [
 // CHECK: .rel.text {
 // CHECK: R_AMDGPU_ABS32_LO SCRATCH_RSRC_DWORD0 0x0
 // CHECK: R_AMDGPU_ABS32_HI SCRATCH_RSRC_DWORD1 0x0
-// CHECK: R_AMDGPU_GOTPCREL global_var 0x0
+// CHECK: R_AMDGPU_GOTPCREL global_var0 0x0
+// CHECK: R_AMDGPU_GOTPCREL32_LO global_var1 0x0
+// CHECK: R_AMDGPU_GOTPCREL32_HI global_var2 0x0
+// CHECK: R_AMDGPU_REL32_LO global_var3 0x0
+// CHECK: R_AMDGPU_REL32_HI global_var4 0x0
 // CHECK: R_AMDGPU_ABS32 var 0x0
 // CHECK: }
 // CHECK: .rel.data {
 // CHECK: R_AMDGPU_ABS64 temp 0x0
 // CHECK: }
 // CHECK: ]
 
 kernel:
   s_mov_b32 s0, SCRATCH_RSRC_DWORD0
   s_mov_b32 s1, SCRATCH_RSRC_DWORD1
-  s_mov_b32 s2, global_var@GOTPCREL
-
-.globl global_var
+  s_mov_b32 s2, global_var0@GOTPCREL
+  s_mov_b32 s3, global_var1@gotpcrel32@lo
+  s_mov_b32 s4, global_var2@gotpcrel32@hi
+  s_mov_b32 s5, global_var3@rel32@lo
+  s_mov_b32 s6, global_var4@rel32@hi
+
+.globl global_var0
+.globl global_var1
+.globl global_var2
+.globl global_var3
+.globl global_var4
 
 .globl SCRATCH_RSRC_DWORD0
 
 .section nonalloc, "w", @progbits
   .long var, common_var
 
 
 // 8 byte relocations
   .type ptr,@object
   .data
   .globl  ptr
   .p2align  3
 ptr:
   .quad temp
   .size ptr, 8