[MC] Pass MCSubtargetInfo to fixupNeedsRelaxation and applyFixup

On targets like Arm some relaxations may only be performed when certain
architectural features are available. As functions can be compiled with
differing levels of architectural support we must make a judgement on
whether we can relax based on the MCSubtargetInfo for the function. This
change passes through the MCSubtargetInfo for the function to
fixupNeedsRelaxation so that the decision on whether to relax can be made
per function. In this patch, only the ARM backend makes use of this
information. We must also pass the MCSubtargetInfo to applyFixup because
some fixups skip error checking on the assumption that relaxation has
occurred, to prevent code-generation errors applyFixup must see the same
MCSubtargetInfo as fixupNeedsRelaxation.

Differential Revision: https://reviews.llvm.org/D44928

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/Target/Lanai/MCTargetDesc/LanaiAsmBackend.cpp b/llvm/lib/Target/Lanai/MCTargetDesc/LanaiAsmBackend.cpp
index 0d01729d393..85fffd9a7c7 100644
--- a/llvm/lib/Target/Lanai/MCTargetDesc/LanaiAsmBackend.cpp
+++ b/llvm/lib/Target/Lanai/MCTargetDesc/LanaiAsmBackend.cpp
@@ -51,7 +51,8 @@ public:
 
   void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
                   const MCValue &Target, MutableArrayRef<char> Data,
-                  uint64_t Value, bool IsResolved) const override;
+                  uint64_t Value, bool IsResolved,
+                  const MCSubtargetInfo *STI) const override;
 
   std::unique_ptr<MCObjectTargetWriter>
   createObjectTargetWriter() const override;
@@ -69,7 +70,8 @@ public:
     return Lanai::NumTargetFixupKinds;
   }
 
-  bool mayNeedRelaxation(const MCInst & /*Inst*/) const override {
+  bool mayNeedRelaxation(const MCInst & /*Inst*/,
+                         const MCSubtargetInfo &STI) const override {
     return false;
   }
 
@@ -93,7 +95,8 @@ bool LanaiAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
 void LanaiAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
                                  const MCValue &Target,
                                  MutableArrayRef<char> Data, uint64_t Value,
-                                 bool /*IsResolved*/) const {
+                                 bool /*IsResolved*/,
+                                 const MCSubtargetInfo */*STI*/) const {
   MCFixupKind Kind = Fixup.getKind();
   Value = adjustFixupValue(static_cast<unsigned>(Kind), Value);