Reapply bottom-up fast-isel, with several fixes for x86-32:
 - Check getBytesToPopOnReturn().
 - Eschew ST0 and ST1 for return values.
 - Fix the PIC base register initialization so that it doesn't ever
   fail to end up the top of the entry block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108039 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86TargetMachine.cpp b/lib/Target/X86/X86TargetMachine.cpp
index a0d7cf6..df00d3f 100644
--- a/lib/Target/X86/X86TargetMachine.cpp
+++ b/lib/Target/X86/X86TargetMachine.cpp
@@ -173,6 +173,10 @@
   // Install an instruction selector.
   PM.add(createX86ISelDag(*this, OptLevel));
 
+  // For 32-bit, prepend instructions to set the "global base reg" for PIC.
+  if (!Subtarget.is64Bit())
+    PM.add(createGlobalBaseRegPass());
+
   return false;
 }