MC: AArch64: Add support for gotpage_lo15

It is not used bt LLVM itself, but it would be used on lld tests
to implement R_AARCH64_LD64_GOTPAGE_LO15 support.

Author: zatrazz

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -750,7 +750,8 @@ class AArch64Operand : public MCParsedAsmOperand {
         ELFRefKind == AArch64MCExpr::VK_GOTTPREL_LO12_NC ||
         ELFRefKind == AArch64MCExpr::VK_TLSDESC_LO12 ||
         ELFRefKind == AArch64MCExpr::VK_SECREL_LO12 ||
-        ELFRefKind == AArch64MCExpr::VK_SECREL_HI12) {
+        ELFRefKind == AArch64MCExpr::VK_SECREL_HI12 ||
+        ELFRefKind == AArch64MCExpr::VK_GOT_PAGE_LO15) {
       // Note that we don't range-check the addend. It's adjusted modulo page
       // size when converted, so there is no "out of range" condition when using
       // @pageoff.
@@ -2569,6 +2570,7 @@ AArch64AsmParser::tryParseAdrpLabel(OperandVector &Operands) {
                DarwinRefKind != MCSymbolRefExpr::VK_TLVPPAGE &&
                ELFRefKind != AArch64MCExpr::VK_ABS_PAGE_NC &&
                ELFRefKind != AArch64MCExpr::VK_GOT_PAGE &&
+               ELFRefKind != AArch64MCExpr::VK_GOT_PAGE_LO15 &&
                ELFRefKind != AArch64MCExpr::VK_GOTTPREL_PAGE &&
                ELFRefKind != AArch64MCExpr::VK_TLSDESC_PAGE) {
       // The operand must be an @page or @gotpage qualified symbolref.
@@ -3436,6 +3438,7 @@ bool AArch64AsmParser::parseSymbolicImmVal(const MCExpr *&ImmVal) {
                   .Case("tprel_lo12_nc", AArch64MCExpr::VK_TPREL_LO12_NC)
                   .Case("tlsdesc_lo12", AArch64MCExpr::VK_TLSDESC_LO12)
                   .Case("got", AArch64MCExpr::VK_GOT_PAGE)
+                  .Case("gotpage_lo15", AArch64MCExpr::VK_GOT_PAGE_LO15)
                   .Case("got_lo12", AArch64MCExpr::VK_GOT_LO12)
                   .Case("gottprel", AArch64MCExpr::VK_GOTTPREL_PAGE)
                   .Case("gottprel_lo12", AArch64MCExpr::VK_GOTTPREL_LO12_NC)

llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp

@@ -322,7 +322,11 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
       if (SymLoc == AArch64MCExpr::VK_ABS && IsNC)
         return R_CLS(LDST64_ABS_LO12_NC);
       if (SymLoc == AArch64MCExpr::VK_GOT && IsNC) {
+        AArch64MCExpr::VariantKind AddressLoc =
+            AArch64MCExpr::getAddressFrag(RefKind);
         if (!IsILP32) {
+          if (AddressLoc == AArch64MCExpr::VK_LO15)
+            return ELF::R_AARCH64_LD64_GOTPAGE_LO15;
           return ELF::R_AARCH64_LD64_GOT_LO12_NC;
         } else {
           Ctx.reportError(Fixup.getLoc(), "ILP32 64-bit load/store "

llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp

@@ -70,6 +70,7 @@ StringRef AArch64MCExpr::getVariantKindName() const {
   case VK_ABS_PAGE_NC:         return ":pg_hi21_nc:";
   case VK_GOT:                 return ":got:";
   case VK_GOT_PAGE:            return ":got:";
+  case VK_GOT_PAGE_LO15:       return ":gotpage_lo15:";
   case VK_GOT_LO12:            return ":got_lo12:";
   case VK_GOTTPREL:            return ":gottprel:";
   case VK_GOTTPREL_PAGE:       return ":gottprel:";

llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h

@@ -46,6 +46,7 @@ class AArch64MCExpr : public MCTargetExpr {
     VK_G1       = 0x050,
     VK_G2       = 0x060,
     VK_G3       = 0x070,
+    VK_LO15     = 0x080,
     VK_AddressFragBits = 0x0f0,
 
     // Whether the final relocation is a checked one (where a linker should
@@ -82,6 +83,7 @@ class AArch64MCExpr : public MCTargetExpr {
     VK_PREL_G0_NC        = VK_PREL     | VK_G0      | VK_NC,
     VK_GOT_LO12          = VK_GOT      | VK_PAGEOFF | VK_NC,
     VK_GOT_PAGE          = VK_GOT      | VK_PAGE,
+    VK_GOT_PAGE_LO15     = VK_GOT      | VK_LO15    | VK_NC,
     VK_DTPREL_G2         = VK_DTPREL   | VK_G2,
     VK_DTPREL_G1         = VK_DTPREL   | VK_G1,
     VK_DTPREL_G1_NC      = VK_DTPREL   | VK_G1      | VK_NC,

llvm/test/MC/AArch64/arm64-elf-relocs.s

@@ -245,6 +245,16 @@ trickQuestion:
 // CHECK-OBJ-LP64: R_AARCH64_LD64_GOT_LO12_NC sym
 // CHECK-OBJ-LP64: R_AARCH64_LD64_GOT_LO12_NC sym+0x7
 
+  ldr x24, [x23, #:gotpage_lo15:sym]
+  ldr d22, [x21, :gotpage_lo15:sym]
+  ldr d22, [x23, :gotpage_lo15:sym+7]
+// CHECK: ldr x24, [x23, :gotpage_lo15:sym]
+// CHECK: ldr d22, [x21, :gotpage_lo15:sym]
+// CHECK: ldr d22, [x23, :gotpage_lo15:sym+7]
+// CHECK-OBJ-LP64: R_AARCH64_LD64_GOTPAGE_LO15 sym{{$}}
+// CHECK-OBJ-LP64: R_AARCH64_LD64_GOTPAGE_LO15 sym{{$}}
+// CHECK-OBJ-LP64: R_AARCH64_LD64_GOTPAGE_LO15 sym+0x7
+
    ldr x24, [x23, :dtprel_lo12_nc:sym]
    ldr d22, [x21, #:dtprel_lo12:sym]
 // CHECK: ldr x24, [x23, :dtprel_lo12_nc:sym]
@@ -305,4 +315,4 @@ trickQuestion:
 // CHECK: ldr x24, :got:sym
 // CHECK: ldr d22, :got:sym
 // CHECK-OBJ-LP64: R_AARCH64_GOT_LD_PREL19 sym
-// CHECK-OBJ-LP64: R_AARCH64_GOT_LD_PREL19 sym
+// CHECK-OBJ-LP64: R_AARCH64_GOT_LD_PREL19 sym