AMDGPUMCCodeEmitter: Set PCRel at fixup creation

Avoid reliance on the MCAssembler::evaluateFixup workaround that checks
MCFixupKindInfo::FKF_IsPCRel. Additionally, standardize how fixups are
appended. This helper will facilitate future fixup data structure
optimizations.

Author: MaskRay

llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp

@@ -175,8 +175,8 @@ AMDGPUAsmBackend::getFixupKind(StringRef Name) const {
 
 MCFixupKindInfo AMDGPUAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
   const static MCFixupKindInfo Infos[AMDGPU::NumTargetFixupKinds] = {
-    // name                   offset bits  flags
-    { "fixup_si_sopp_br",     0,     16,   MCFixupKindInfo::FKF_IsPCRel },
+      // name                   offset bits  flags
+      {"fixup_si_sopp_br", 0, 16, 0},
   };
 
   if (mc::isRelocation(Kind))

llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCCodeEmitter.cpp

@@ -103,6 +103,11 @@ MCCodeEmitter *llvm::createAMDGPUMCCodeEmitter(const MCInstrInfo &MCII,
   return new AMDGPUMCCodeEmitter(MCII, *Ctx.getRegisterInfo());
 }
 
+static void addFixup(SmallVectorImpl<MCFixup> &Fixups, uint32_t Offset,
+                     const MCExpr *Value, uint16_t Kind, bool PCRel = false) {
+  Fixups.push_back(MCFixup::create(Offset, Value, Kind, PCRel));
+}
+
 // Returns the encoding value to use if the given integer is an integer inline
 // immediate value, or 0 if it is not.
 template <typename IntTy>
@@ -445,8 +450,7 @@ void AMDGPUMCCodeEmitter::getSOPPBrEncoding(const MCInst &MI, unsigned OpNo,
 
   if (MO.isExpr()) {
     const MCExpr *Expr = MO.getExpr();
-    MCFixupKind Kind = (MCFixupKind)AMDGPU::fixup_si_sopp_br;
-    Fixups.push_back(MCFixup::create(0, Expr, Kind));
+    addFixup(Fixups, 0, Expr, AMDGPU::fixup_si_sopp_br, true);
     Op = APInt::getZero(96);
   } else {
     getMachineOpValue(MI, MO, Op, Fixups, STI);
@@ -661,8 +665,7 @@ void AMDGPUMCCodeEmitter::getMachineOpValueCommon(
     const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
     uint32_t Offset = Desc.getSize();
     assert(Offset == 4 || Offset == 8);
-
-    Fixups.push_back(MCFixup::create(Offset, MO.getExpr(), Kind));
+    addFixup(Fixups, Offset, MO.getExpr(), Kind, Kind == FK_PCRel_4);
   }
 
   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());