Add a helper to MCExpr for when an expression is know to be absolute.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215713 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCExpr.h

@@ -50,6 +50,11 @@ private:
   bool EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
                           const MCAsmLayout *Layout,
                           const SectionAddrMap *Addrs) const;
+
+  bool evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
+                          const MCAsmLayout *Layout,
+                          const SectionAddrMap *Addrs, bool InSet) const;
+
 protected:
   explicit MCExpr(ExprKind _Kind) : Kind(_Kind) {}
 
@@ -89,6 +94,8 @@ public:
   bool EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const;
   bool EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout &Layout) const;
 
+  int64_t evaluateKnownAbsolute(const MCAsmLayout &Layout) const;
+
   /// EvaluateAsRelocatable - Try to evaluate the expression to a relocatable
   /// value, i.e. an expression of the fixed form (a - b + constant).
   ///

lib/MC/MCAssembler.cpp

@@ -994,11 +994,8 @@ bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
 }
 
 bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
-  int64_t Value = 0;
   uint64_t OldSize = LF.getContents().size();
-  bool IsAbs = LF.getValue().EvaluateAsAbsolute(Value, Layout);
+  int64_t Value = LF.getValue().evaluateKnownAbsolute(Layout);
-  (void)IsAbs;
-  assert(IsAbs);
   SmallString<8> &Data = LF.getContents();
   Data.clear();
   raw_svector_ostream OSE(Data);
@@ -1013,11 +1010,8 @@ bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
 bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
                                      MCDwarfLineAddrFragment &DF) {
   MCContext &Context = Layout.getAssembler().getContext();
-  int64_t AddrDelta = 0;
   uint64_t OldSize = DF.getContents().size();
-  bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
+  int64_t AddrDelta = DF.getAddrDelta().evaluateKnownAbsolute(Layout);
-  (void)IsAbs;
-  assert(IsAbs);
   int64_t LineDelta;
   LineDelta = DF.getLineDelta();
   SmallString<8> &Data = DF.getContents();
@@ -1031,11 +1025,8 @@ bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
 bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
                                               MCDwarfCallFrameFragment &DF) {
   MCContext &Context = Layout.getAssembler().getContext();
-  int64_t AddrDelta = 0;
   uint64_t OldSize = DF.getContents().size();
-  bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
+  int64_t AddrDelta = DF.getAddrDelta().evaluateKnownAbsolute(Layout);
-  (void)IsAbs;
-  assert(IsAbs);
   SmallString<8> &Data = DF.getContents();
   Data.clear();
   raw_svector_ostream OSE(Data);

lib/MC/MCExpr.cpp

@@ -467,9 +467,27 @@ bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
   return EvaluateAsAbsolute(Res, &Asm, nullptr, nullptr);
 }
 
+int64_t MCExpr::evaluateKnownAbsolute(const MCAsmLayout &Layout) const {
+  int64_t Res;
+  bool Abs =
+      evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, true);
+  (void)Abs;
+  assert(Abs && "Not actually absolute");
+  return Res;
+}
+
 bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
                                 const MCAsmLayout *Layout,
                                 const SectionAddrMap *Addrs) const {
+  // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
+  // absolutize differences across sections and that is what the MachO writer
+  // uses Addrs for.
+  return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs);
+}
+
+bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
+                                const MCAsmLayout *Layout,
+                                const SectionAddrMap *Addrs, bool InSet) const {
   MCValue Value;
 
   // Fast path constants.
@@ -478,12 +496,8 @@ bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
     return true;
   }
 
-  // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
+  bool IsRelocatable = EvaluateAsRelocatableImpl(
-  // absolutize differences across sections and that is what the MachO writer
+      Value, Asm, Layout, nullptr, Addrs, InSet, /*ForceVarExpansion*/ false);
-  // uses Addrs for.
-  bool IsRelocatable =
-      EvaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs,
-                                /*InSet*/ Addrs, /*ForceVarExpansion*/ false);
 
   // Record the current value.
   Res = Value.getConstant();

lib/MC/MCObjectStreamer.cpp

@@ -144,7 +144,6 @@ void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
     EmitULEB128IntValue(IntValue);
     return;
   }
-  Value = ForceExpAbs(Value);
   insert(new MCLEBFragment(*Value, false));
 }
 
@@ -154,7 +153,6 @@ void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
     EmitSLEB128IntValue(IntValue);
     return;
   }
-  Value = ForceExpAbs(Value);
   insert(new MCLEBFragment(*Value, true));
 }
 
@@ -280,7 +278,6 @@ void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
     MCDwarfLineAddr::Emit(this, LineDelta, Res);
     return;
   }
-  AddrDelta = ForceExpAbs(AddrDelta);
   insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
 }
 
@@ -292,7 +289,6 @@ void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
     MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
     return;
   }
-  AddrDelta = ForceExpAbs(AddrDelta);
   insert(new MCDwarfCallFrameFragment(*AddrDelta));
 }