IR headers moved to llvm/IR some aeons ago, update documentation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185854 91177308-0d34-0410-b5e6-96231b3b80d8
PPC: Mark vector CC action for SETO and SETONE as Expand

Another bug found by llvm-stress! This fixes hitting
  llvm_unreachable("Invalid integer vector compare condition");
at the end of getVCmpInst in PPCISelDAGToDAG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185855 91177308-0d34-0410-b5e6-96231b3b80d8

[PowerPC] Always use "assembler dialect" 1

A setting in MCAsmInfo defines the "assembler dialect" to use.  This is used
by common code to choose between alternatives in a multi-alternative GNU
inline asm statement like the following:

  __asm__ ("{sfe|subfe} %0,%1,%2" : "=r" (out) : "r" (in1), "r" (in2));

The meaning of these dialects is platform specific, and GCC defines those
for PowerPC to use dialect 0 for old-style (POWER) mnemonics and 1 for
new-style (PowerPC) mnemonics, like in the example above.

To be compatible with inline asm used with GCC, LLVM ought to do the same.
Specifically, this means we should always use assembler dialect 1 since
old-style mnemonics really aren't supported on any current platform.

However, the current LLVM back-end uses:
  AssemblerDialect = 1;           // New-Style mnemonics.
in PPCMCAsmInfoDarwin, and
  AssemblerDialect = 0;           // Old-Style mnemonics.
in PPCLinuxMCAsmInfo.

The Linux setting really isn't correct, we should be using new-style
mnemonics everywhere.  This is changed by this commit.

Unfortunately, the setting of this variable is overloaded in the back-end
to decide whether or not we are on a Darwin target.  This is done in
PPCInstPrinter (the "SyntaxVariant" is initialized from the MCAsmInfo
AssemblerDialect setting), and also in PPCMCExpr.  Setting AssemblerDialect
to 1 for both Darwin and Linux no longer allows us to make this distinction.

Instead, this patch uses the MCSubtargetInfo passed to createPPCMCInstPrinter
to distinguish Darwin targets, and ignores the SyntaxVariant parameter.
As to PPCMCExpr, this patch adds an explicit isDarwin argument that needs
to be passed in by the caller when creating a target MCExpr.  (To do so
this patch implicitly also reverts commit 184441.)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185858 91177308-0d34-0410-b5e6-96231b3b80d8
Allow llvm_find_program to find alternate names

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185859 91177308-0d34-0410-b5e6-96231b3b80d8
Find xdot or xdot.py.

Ubuntu installs this as xdot, so finding xdot.py would fail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185860 91177308-0d34-0410-b5e6-96231b3b80d8
Revert r185852.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185861 91177308-0d34-0410-b5e6-96231b3b80d8