ARM: Add a postRA pass to legalize stack offsets. Greedy approach (reserve IP).

src/IceClFlags.h

Index: src/IceClFlags.h
diff --git a/src/IceClFlags.h b/src/IceClFlags.h
index 97420eaa4c7ce870ef86eabde0a7d3215c13287a..70e590cc166cbc005a2ed001c9829e7cf51c6633 100644
--- a/src/IceClFlags.h
+++ b/src/IceClFlags.h
@@ -139,6 +139,14 @@ public:
   void setTargetInstructionSet(TargetInstructionSet NewValue) {
     TInstrSet = NewValue;
   }
+  uint32_t getTestStackExtra() const {
+    return BuildDefs::minimal() ? 0 : TestStackExtra;
+  }
+  void setTestStackExtra(uint32_t NewValue) {
+    if (BuildDefs::minimal())
+      return;
+    TestStackExtra = NewValue;
+  }
 
   VerboseMask getVerbose() const {
     return BuildDefs::dump() ? VMask : (VerboseMask)IceV_None;
@@ -253,6 +261,7 @@ private:
   int RandomNopProbabilityAsPercentage;
   uint32_t ReorderFunctionsWindowSize;
   TargetArch TArch;
+  uint32_t TestStackExtra;
   TargetInstructionSet TInstrSet;
   VerboseMask VMask;