MCExpr: Make COFF-specific VK_SECREL target-specific

to align with ELF targets, where the relocation specifier constants are
all target-specific.

Author: MaskRay

llvm/include/llvm/MC/MCExpr.h

@@ -193,13 +193,10 @@ class MCSymbolRefExpr : public MCExpr {
   // VariantKind isn't ideal for encoding relocation operators because:
   // (a) other expressions, like MCConstantExpr (e.g., 4@l) and MCBinaryExpr
   // (e.g., (a+1)@l), also need it; (b) semantics become unclear (e.g., folding
-  // expressions with @). MCTargetExpr, as used by AArch64 and RISC-V, offers a
-  // cleaner approach.
+  // expressions with @). MCSpecifierExpr, as used by AArch64 and RISC-V, offers
+  // a cleaner approach.
   enum VariantKind : uint16_t {
-    VK_SECREL = 1,
-    VK_WEAKREF, // The link between the symbols in .weakref foo, bar
-
-    VK_COFF_IMGREL32, // symbol@imgrel (image-relative)
+    VK_COFF_IMGREL32 = 3, // symbol@imgrel (image-relative)
 
     FirstTargetSpecifier,
   };

llvm/lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp

@@ -102,8 +102,6 @@ unsigned AArch64WinCOFFObjectWriter::getRelocType(
       return COFF::IMAGE_REL_ARM64_ADDR32;
     case MCSymbolRefExpr::VK_COFF_IMGREL32:
       return COFF::IMAGE_REL_ARM64_ADDR32NB;
-    case MCSymbolRefExpr::VK_SECREL:
-      return COFF::IMAGE_REL_ARM64_SECREL;
     }
 
   case FK_Data_8:

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -859,7 +859,7 @@ static uint8_t getModifierSpecifier(ARMCP::ARMCPModifier Modifier) {
   case ARMCP::GOT_PREL:
     return ARM::S_GOT_PREL;
   case ARMCP::SECREL:
-    return MCSymbolRefExpr::VK_SECREL;
+    return ARM::S_COFF_SECREL;
   }
   llvm_unreachable("Invalid ARMCPModifier!");
 }

llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp

@@ -34,7 +34,7 @@ const MCAsmInfo::AtSpecifier atSpecifiers[] = {
     {ARM::S_GOTTPOFF, "GOTTPOFF"},
     {ARM::S_GOTTPOFF_FDPIC, "gottpoff_fdpic"},
     {ARM::S_PLT, "PLT"},
-    {MCSymbolRefExpr::VK_SECREL, "SECREL32"},
+    {ARM::S_COFF_SECREL, "SECREL32"},
     {ARM::S_TLSCALL, "tlscall"},
     {ARM::S_TLSDESC, "tlsdesc"},
     {ARM::S_TLSGD, "TLSGD"},

llvm/lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.h

@@ -92,6 +92,8 @@ namespace ARM {
 using Specifier = uint16_t;
 enum {
   S_None,
+  S_COFF_SECREL,
+
   S_HI16 =
       MCSymbolRefExpr::FirstTargetSpecifier, // The R_ARM_MOVT_ABS relocation
                                              // (:upper16: in the .s file)

llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/ARMFixupKinds.h"
+#include "MCTargetDesc/ARMMCAsmInfo.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/MC/MCAsmBackend.h"
@@ -64,7 +65,7 @@ unsigned ARMWinCOFFObjectWriter::getRelocType(MCContext &Ctx,
     switch (Spec) {
     case MCSymbolRefExpr::VK_COFF_IMGREL32:
       return COFF::IMAGE_REL_ARM_ADDR32NB;
-    case MCSymbolRefExpr::VK_SECREL:
+    case ARM::S_COFF_SECREL:
       return COFF::IMAGE_REL_ARM_SECREL;
     default:
       return COFF::IMAGE_REL_ARM_ADDR32;

llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp

@@ -53,7 +53,7 @@ const MCAsmInfo::AtSpecifier atSpecifiers[] = {
     {X86::S_PCREL, "PCREL"},
     {X86::S_PLT, "PLT"},
     {X86::S_PLTOFF, "PLTOFF"},
-    {MCSymbolRefExpr::VK_SECREL, "SECREL32"},
+    {X86::S_COFF_SECREL, "SECREL32"},
     {X86::S_SIZE, "SIZE"},
     {X86::S_TLSCALL, "tlscall"},
     {X86::S_TLSDESC, "tlsdesc"},

llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.h

@@ -69,6 +69,7 @@ using Specifier = uint16_t;
 
 enum {
   S_None,
+  S_COFF_SECREL,
 
   S_ABS8 = MCSymbolRefExpr::FirstTargetSpecifier,
   S_DTPOFF,

llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp

@@ -496,7 +496,7 @@ startsWithGlobalOffsetTable(const MCExpr *Expr) {
 static bool hasSecRelSymbolRef(const MCExpr *Expr) {
   if (Expr->getKind() == MCExpr::SymbolRef) {
     auto *Ref = static_cast<const MCSymbolRefExpr *>(Expr);
-    return Ref->getKind() == MCSymbolRefExpr::VK_SECREL;
+    return Ref->getSpecifier() == X86::S_COFF_SECREL;
   }
   return false;
 }

llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/X86FixupKinds.h"
+#include "MCTargetDesc/X86MCAsmInfo.h"
 #include "MCTargetDesc/X86MCTargetDesc.h"
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/MC/MCContext.h"
@@ -76,7 +77,7 @@ unsigned X86WinCOFFObjectWriter::getRelocType(MCContext &Ctx,
     case X86::reloc_signed_4byte_relax:
       if (Spec == MCSymbolRefExpr::VK_COFF_IMGREL32)
         return COFF::IMAGE_REL_AMD64_ADDR32NB;
-      if (Spec == MCSymbolRefExpr::VK_SECREL)
+      if (Spec == X86::S_COFF_SECREL)
         return COFF::IMAGE_REL_AMD64_SECREL;
       return COFF::IMAGE_REL_AMD64_ADDR32;
     case FK_Data_8:
@@ -100,7 +101,7 @@ unsigned X86WinCOFFObjectWriter::getRelocType(MCContext &Ctx,
     case X86::reloc_signed_4byte_relax:
       if (Spec == MCSymbolRefExpr::VK_COFF_IMGREL32)
         return COFF::IMAGE_REL_I386_DIR32NB;
-      if (Spec == MCSymbolRefExpr::VK_SECREL)
+      if (Spec == X86::S_COFF_SECREL)
         return COFF::IMAGE_REL_I386_SECREL;
       return COFF::IMAGE_REL_I386_DIR32;
     case FK_SecRel_2: