[llvm-branch-commits] [llvm-branch] r104769 - in /llvm/branches/Apple/whitney: include/llvm/Target/TargetAsmBackend.h lib/MC/MCAssembler.cpp lib/MC/MCMachOStreamer.cpp lib/Target/X86/X86AsmBackend.cpp

[Daniel Dunbar]

Author: ddunbar
Date: Wed May 26 17:29:05 2010
New Revision: 104769

URL: http://llvm.org/viewvc/llvm-project?rev=104769&view=rev
Log:
MC: Simplify MayNeedRelaxation to not provide the fixups, so we can query it before encoding.

Modified:
    llvm/branches/Apple/whitney/include/llvm/Target/TargetAsmBackend.h
    llvm/branches/Apple/whitney/lib/MC/MCAssembler.cpp
    llvm/branches/Apple/whitney/lib/MC/MCMachOStreamer.cpp
    llvm/branches/Apple/whitney/lib/Target/X86/X86AsmBackend.cpp

Modified: llvm/branches/Apple/whitney/include/llvm/Target/TargetAsmBackend.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/whitney/include/llvm/Target/TargetAsmBackend.h?rev=104769&r1=104768&r2=104769&view=diff
==============================================================================
--- llvm/branches/Apple/whitney/include/llvm/Target/TargetAsmBackend.h (original)
+++ llvm/branches/Apple/whitney/include/llvm/Target/TargetAsmBackend.h Wed May 26 17:29:05 2010
@@ -112,10 +112,7 @@
   /// relaxation.
   ///
   /// \arg Inst - The instruction to test.
-  /// \arg Fixups - The actual fixups this instruction encoded to, for potential
-  /// use by the target backend.
-  virtual bool MayNeedRelaxation(const MCInst &Inst,
-                           const SmallVectorImpl<MCFixup> &Fixups) const = 0;
+  virtual bool MayNeedRelaxation(const MCInst &Inst) const = 0;
 
   /// RelaxInstruction - Relax the instruction in the given fragment to the next
   /// wider instruction.

Modified: llvm/branches/Apple/whitney/lib/MC/MCAssembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/whitney/lib/MC/MCAssembler.cpp?rev=104769&r1=104768&r2=104769&view=diff
==============================================================================
--- llvm/branches/Apple/whitney/lib/MC/MCAssembler.cpp (original)
+++ llvm/branches/Apple/whitney/lib/MC/MCAssembler.cpp Wed May 26 17:29:05 2010
@@ -787,7 +787,7 @@
   // If this inst doesn't ever need relaxation, ignore it. This occurs when we
   // are intentionally pushing out inst fragments, or because we relaxed a
   // previous instruction to one that doesn't need relaxation.
-  if (!getBackend().MayNeedRelaxation(IF->getInst(), IF->getFixups()))
+  if (!getBackend().MayNeedRelaxation(IF->getInst()))
     return false;
 
   for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),

Modified: llvm/branches/Apple/whitney/lib/MC/MCMachOStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/whitney/lib/MC/MCMachOStreamer.cpp?rev=104769&r1=104768&r2=104769&view=diff
==============================================================================
--- llvm/branches/Apple/whitney/lib/MC/MCMachOStreamer.cpp (original)
+++ llvm/branches/Apple/whitney/lib/MC/MCMachOStreamer.cpp Wed May 26 17:29:05 2010
@@ -451,7 +451,7 @@
   // total knowledge about undefined symbols at that point). Even now, though,
   // we can do a decent job, especially on Darwin where scattering means that we
   // are going to often know that we can never fully resolve a fixup.
-  if (Assembler.getBackend().MayNeedRelaxation(Inst, AsmFixups)) {
+  if (Assembler.getBackend().MayNeedRelaxation(Inst)) {
     MCInstFragment *IF = new MCInstFragment(Inst, CurSectionData);
     IF->setAtom(CurrentAtomMap.lookup(CurSectionData));
 

Modified: llvm/branches/Apple/whitney/lib/Target/X86/X86AsmBackend.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/whitney/lib/Target/X86/X86AsmBackend.cpp?rev=104769&r1=104768&r2=104769&view=diff
==============================================================================
--- llvm/branches/Apple/whitney/lib/Target/X86/X86AsmBackend.cpp (original)
+++ llvm/branches/Apple/whitney/lib/Target/X86/X86AsmBackend.cpp Wed May 26 17:29:05 2010
@@ -54,8 +54,7 @@
       DF.getContents()[Fixup.getOffset() + i] = uint8_t(Value >> (i * 8));
   }
 
-  bool MayNeedRelaxation(const MCInst &Inst,
-                         const SmallVectorImpl<MCFixup> &Fixups) const;
+  bool MayNeedRelaxation(const MCInst &Inst) const;
 
   void RelaxInstruction(const MCInstFragment *IF, MCInst &Res) const;
 
@@ -88,31 +87,16 @@
   }
 }
 
-bool X86AsmBackend::MayNeedRelaxation(const MCInst &Inst,
-                              const SmallVectorImpl<MCFixup> &Fixups) const {
-  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
-    const MCFixup &F = Fixups[i];
-
-    // We don't support relaxing anything else currently. Make sure we error out
-    // if we see a non-constant 1 or 2 byte fixup.
-    //
-    // FIXME: We should need to check this here, this is better checked in the
-    // object writer which should be verifying that any final relocations match
-    // the expected fixup. However, that code is more complicated and hasn't
-    // been written yet. See the FIXMEs in MachObjectWriter.cpp.
-    if ((F.getKind() == FK_Data_1 || F.getKind() == FK_Data_2) &&
-        !isa<MCConstantExpr>(F.getValue()))
-      report_fatal_error("unexpected small fixup with a non-constant operand!");
-
-    // Check for a 1byte pcrel fixup, and enforce that we would know how to
-    // relax this instruction.
-    if (unsigned(F.getKind()) == X86::reloc_pcrel_1byte) {
-      assert(getRelaxedOpcode(Inst.getOpcode()) != Inst.getOpcode());
-      return true;
-    }
-  }
-
-  return false;
+bool X86AsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
+  // Check if this instruction is ever relaxable.
+  if (getRelaxedOpcode(Inst.getOpcode()) == Inst.getOpcode())
+    return false;
+
+  // If so, just assume it can be relaxed. Once we support relaxing more complex
+  // instructions we should check that the instruction actually has symbolic
+  // operands before doing this, but we need to be careful about things like
+  // PCrel.
+  return true;
 }
 
 // FIXME: Can tblgen help at all here to verify there aren't other instructions