IPRA: Run RegUsageInfoPropagate much later

This was running immediately after isel, before
isel pseudos were even expanded which is really
unreasonable. Move this to before pre-reglloc
passes in case some other pre-regalloc pass wants to
use the updated regmask info.

Fixes one of the reasons IPRA doesn't do anything on
AMDGPU currently. Tests will be included with future
patch after a few more are fixed.

llvm-svn: 310875

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -779,9 +779,6 @@ void TargetPassConfig::addMachinePasses() {
   // Print the instruction selected machine code...
   printAndVerify("After Instruction Selection");
 
-  if (TM->Options.EnableIPRA)
-    addPass(createRegUsageInfoPropPass());
-
   // Expand pseudo-instructions emitted by ISel.
   addPass(&ExpandISelPseudosID);
 
@@ -794,6 +791,9 @@ void TargetPassConfig::addMachinePasses() {
     addPass(&LocalStackSlotAllocationID, false);
   }
 
+  if (TM->Options.EnableIPRA)
+    addPass(createRegUsageInfoPropPass());
+
   // Run pre-ra passes.
   addPreRegAlloc();