[llvm] r239552 - Generalize emitAbsoluteSymbolDiff.

[Rafael Espindola]

Author: rafael
Date: Thu Jun 11 13:58:08 2015
New Revision: 239552

URL: http://llvm.org/viewvc/llvm-project?rev=239552&view=rev
Log:
Generalize emitAbsoluteSymbolDiff.

This makes emitAbsoluteSymbolDiff always succeed and moves logic from the asm
printer to it.

The object one now also works on ELF. If two symbols are in the same fragment,
we will never move them apart.

Modified:
    llvm/trunk/include/llvm/MC/MCObjectStreamer.h
    llvm/trunk/include/llvm/MC/MCStreamer.h
    llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
    llvm/trunk/lib/MC/MCObjectStreamer.cpp
    llvm/trunk/lib/MC/MCStreamer.cpp

Modified: llvm/trunk/include/llvm/MC/MCObjectStreamer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCObjectStreamer.h?rev=239552&r1=239551&r2=239552&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCObjectStreamer.h (original)
+++ llvm/trunk/include/llvm/MC/MCObjectStreamer.h Thu Jun 11 13:58:08 2015
@@ -136,7 +136,7 @@ public:
   ///
   /// \pre Offset of \c Hi is greater than the offset \c Lo.
   /// \return true on success.
-  bool emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
+  void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
                               unsigned Size) override;
 
   bool mayHaveInstructions(MCSection &Sec) const override;

Modified: llvm/trunk/include/llvm/MC/MCStreamer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCStreamer.h?rev=239552&r1=239551&r2=239552&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCStreamer.h (original)
+++ llvm/trunk/include/llvm/MC/MCStreamer.h Thu Jun 11 13:58:08 2015
@@ -636,14 +636,12 @@ public:
                                      unsigned Isa, unsigned Discriminator,
                                      StringRef FileName);
 
-  /// Emit the absolute difference between two symbols if possible.
+  /// Emit the absolute difference between two symbols.
   ///
   /// \pre Offset of \c Hi is greater than the offset \c Lo.
   /// \return true on success.
-  virtual bool emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
-                                      unsigned Size) {
-    return false;
-  }
+  virtual void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
+                                      unsigned Size);
 
   virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID);
   virtual void EmitCFISections(bool EH, bool Debug);

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=239552&r1=239551&r2=239552&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Thu Jun 11 13:58:08 2015
@@ -1590,25 +1590,7 @@ void AsmPrinter::EmitInt32(int Value) co
 /// .set if it avoids relocations.
 void AsmPrinter::EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
                                      unsigned Size) const {
-  if (!MAI->doesDwarfUseRelocationsAcrossSections())
-    if (OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, Size))
-      return;
-
-  // Get the Hi-Lo expression.
-  const MCExpr *Diff =
-    MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, OutContext),
-                            MCSymbolRefExpr::create(Lo, OutContext),
-                            OutContext);
-
-  if (!MAI->doesSetDirectiveSuppressesReloc()) {
-    OutStreamer->EmitValue(Diff, Size);
-    return;
-  }
-
-  // Otherwise, emit with .set (aka assignment).
-  MCSymbol *SetLabel = createTempSymbol("set");
-  OutStreamer->EmitAssignment(SetLabel, Diff);
-  OutStreamer->EmitSymbolValue(SetLabel, Size);
+  OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, Size);
 }
 
 /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"

Modified: llvm/trunk/lib/MC/MCObjectStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectStreamer.cpp?rev=239552&r1=239551&r2=239552&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCObjectStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCObjectStreamer.cpp Thu Jun 11 13:58:08 2015
@@ -54,21 +54,18 @@ void MCObjectStreamer::flushPendingLabel
   }
 }
 
-bool MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
+void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
                                               const MCSymbol *Lo,
                                               unsigned Size) {
-  // Must both be assigned to the same (valid) fragment.
-  if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment())
-    return false;
-
-  // Must be a data fragment.
-  if (!isa<MCDataFragment>(Hi->getFragment()))
-    return false;
+  // If not assigned to the same (valid) fragment, fallback.
+  if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment()) {
+    MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size);
+    return;
+  }
 
   assert(Hi->getOffset() >= Lo->getOffset() &&
          "Expected Hi to be greater than Lo");
   EmitIntValue(Hi->getOffset() - Lo->getOffset(), Size);
-  return true;
 }
 
 void MCObjectStreamer::reset() {

Modified: llvm/trunk/lib/MC/MCStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCStreamer.cpp?rev=239552&r1=239551&r2=239552&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCStreamer.cpp Thu Jun 11 13:58:08 2015
@@ -638,6 +638,25 @@ void MCStreamer::EmitInstruction(const M
       visitUsedExpr(*Inst.getOperand(i).getExpr());
 }
 
+void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
+                                        unsigned Size) {
+  // Get the Hi-Lo expression.
+  const MCExpr *Diff =
+      MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
+                              MCSymbolRefExpr::create(Lo, Context), Context);
+
+  const MCAsmInfo *MAI = Context.getAsmInfo();
+  if (!MAI->doesSetDirectiveSuppressesReloc()) {
+    EmitValue(Diff, Size);
+    return;
+  }
+
+  // Otherwise, emit with .set (aka assignment).
+  MCSymbol *SetLabel = Context.createTempSymbol("set", true);
+  EmitAssignment(SetLabel, Diff);
+  EmitSymbolValue(SetLabel, Size);
+}
+
 void MCStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {}
 void MCStreamer::EmitThumbFunc(MCSymbol *Func) {}
 void MCStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}