add a registry key to force spill compression

There is correctness and compiliation time regression(Blender) when force spill compression by default

Author: bcheng0127

visa/GraphColor.cpp

@@ -9742,6 +9742,9 @@ unsigned GlobalRA::computeSpillSize(const LIVERANGE_LIST &spilledLRs) {
 
 bool GlobalRA::spillSpaceCompression(int spillSize,
                                      const int globalScratchOffset) {
+  if (builder.getOption(vISA_ForceSpillSpaceCompression))
+    return true;
+
   // factor 1.2 is used to count in the space used for the following
   // iterations. Generally, the most spill will happen in first iteration.
   if ((spillSize * 1.2) <

visa/include/VISAOptionsDefs.h

@@ -291,6 +291,8 @@ DEF_VISA_OPTION(vISA_GRFSpillCodeCleanup, ET_BOOL, "-spillCleanup", UNUSED,
                 true)
 DEF_VISA_OPTION(vISA_SpillSpaceCompression, ET_BOOL, "-nospillcompression",
                 UNUSED, true)
+DEF_VISA_OPTION(vISA_ForceSpillSpaceCompression, ET_BOOL, "-forcespillcompression",
+                UNUSED, false)
 DEF_VISA_OPTION(vISA_ConsiderLoopInfoInRA, ET_BOOL, "-noloopra", UNUSED, true)
 DEF_VISA_OPTION(vISA_ReserveR0, ET_BOOL, "-reserveR0", UNUSED, false)
 DEF_VISA_OPTION(vISA_SpiltLLR, ET_BOOL, "-nosplitllr", UNUSED, true)