svn commit: r247156 - stable/9/contrib/llvm/lib/Target/X86

[Dimitry Andric]

Author: dim
Date: Fri Feb 22 18:33:42 2013
New Revision: 247156
URL: http://svnweb.freebsd.org/changeset/base/247156

Log:
  MFC r246858:
  
  Pull in r175057 from upstream llvm trunk:
  
    X86: Disable generation of rep;movsl when %esi is used as a base pointer.
  
    This happens when there is both stack realignment and a dynamic alloca in the
    function. If we overwrite %esi (rep;movsl uses fixed registers) we'll lose the
    base pointer and the next register spill will write into oblivion.
  
    Fixes PR15249 and unbreaks firefox on i386/freebsd. Mozilla uses dynamic allocas
    and freebsd a 4 byte stack alignment.

Modified:
  stable/9/contrib/llvm/lib/Target/X86/X86SelectionDAGInfo.cpp
Directory Properties:
  stable/9/contrib/llvm/   (props changed)

Modified: stable/9/contrib/llvm/lib/Target/X86/X86SelectionDAGInfo.cpp
==============================================================================
--- stable/9/contrib/llvm/lib/Target/X86/X86SelectionDAGInfo.cpp	Fri Feb 22 18:30:41 2013	(r247155)
+++ stable/9/contrib/llvm/lib/Target/X86/X86SelectionDAGInfo.cpp	Fri Feb 22 18:33:42 2013	(r247156)
@@ -202,6 +202,14 @@ X86SelectionDAGInfo::EmitTargetCodeForMe
       SrcPtrInfo.getAddrSpace() >= 256)
     return SDValue();
 
+  // ESI might be used as a base pointer, in that case we can't simply overwrite
+  // the register.  Fall back to generic code.
+  const X86RegisterInfo *TRI =
+      static_cast<const X86RegisterInfo *>(DAG.getTarget().getRegisterInfo());
+  if (TRI->hasBasePointer(DAG.getMachineFunction()) &&
+      TRI->getBaseRegister() == X86::ESI)
+    return SDValue();
+
   MVT AVT;
   if (Align & 1)
     AVT = MVT::i8;