[PATCH] Add support for small-model PIC for PowerPC.

[hfinkel at anl.gov]

================
Comment at: lib/Target/PowerPC/PPCAsmPrinter.cpp:323
@@ +322,3 @@
+    // Transform %LR = MoveGOTtoLR
+    // Into this: bl _GLOBAL_OFFSET_TABLE_ at local-4
+    MCSymbol *GOTSymbol = OutContext.GetOrCreateSymbol(StringRef("_GLOBAL_OFFSET_TABLE_"));
----------------
It would be nice to have a comment here explaining what the 4 means.

================
Comment at: lib/Target/PowerPC/PPCAsmPrinter.cpp:415
@@ +414,3 @@
+      const MCExpr *PB =
+        MCSymbolRefExpr::Create(OutContext.GetOrCreateSymbol(Twine(".LTOC.")),
+                                                             OutContext);
----------------
Why?

================
Comment at: lib/Target/PowerPC/PPCISelLowering.cpp:1700
@@ -1697,1 +1699,3 @@
+      else
+        GOTPtr = DAG.getNode(PPCISD::GlobalBaseReg, dl, PtrVT);
     }
----------------
Should we rename the GOTPtr variable?

================
Comment at: lib/Target/PowerPC/PPCISelLowering.cpp:1733
@@ -1727,1 +1732,3 @@
+      else
+        GOTPtr = DAG.getNode(PPCISD::GlobalBaseReg, dl, PtrVT);
     }
----------------
Same here.

================
Comment at: lib/Target/PowerPC/PPCInstrInfo.td:3694
@@ -3692,1 +3693,2 @@
 defm : TrapExtendedMnemonic<"u", 31>;
+
----------------
Don't need to add a line here.

================
Comment at: test/CodeGen/PowerPC/ppc32-pic.ll:11
@@ -9,13 +10,3 @@
 
-; CHECK:       [[POFF:\.L[0-9]+\$poff]]:
-; CHECK-NEXT:    .long .L.TOC.-[[PB:\.L[0-9]+\$pb]]
-; CHECK-NEXT:  foo:
-; CHECK:         bl [[PB]]
-; CHECK-NEXT:  [[PB]]:
-; CHECK:         mflr 30
-; CHECK:         lwz [[REG:[0-9]+]], [[POFF]]-[[PB]](30)
-; CHECK-NEXT:    add 30, [[REG]], 30
-; CHECK:         lwz [[VREG:[0-9]+]], [[VREF:\.LC[0-9]+]]-.L.TOC.(30)
-; CHECK:         lwz {{[0-9]+}}, 0([[VREG]])
-; CHECK:       [[VREF]]:
-; CHECK-NEXT:    .long foobar
+; SMALL-BSS:      foo:
+; SMALL-BSS:         bl _GLOBAL_OFFSET_TABLE_ at local-4
----------------
SMALL-BSS-LABEL: foo

(but make the name something that is not a substring of other things)

http://reviews.llvm.org/D5399