[Autobackout][FuncReg]Revert of change: 999667c

 Use max PTSS supported when using stack calls as estimating size needed to store BE stack is not always possible.

Use max PTSS supported when using stack calls as estimating size needed to store BE stack is not always possible.

Author: pratikashar

visa/GraphColor.cpp

@@ -10375,7 +10375,7 @@ int GlobalRA::coloringRegAlloc()
             builder.kernel.fg.frameSizeInOWord > 0;
         jitInfo->hasStackcalls = kernel.fg.getHasStackCalls();
 
-        if (jitInfo->hasStackcalls && builder.getIsKernel()) {
+        if (builder.kernel.fg.frameSizeInOWord != 0) {
             // jitInfo->spillMemUsed is the entire visa stack size. Consider the caller/callee
             // save size if having caller/callee save
             // globalScratchOffset in unit of byte, others in Oword
@@ -10389,16 +10389,12 @@ int GlobalRA::coloringRegAlloc()
             //  callerSaveAreaOffset    -> ---------------------
             //                             |  caller save      |
             //  paramOverflowAreaOffset -> ---------------------
+            jitInfo->spillMemUsed =
+                builder.kernel.fg.frameSizeInOWord * 16;
 
-            // Since it is difficult to predict amount of space needed to store stack, we
-            // reserve maximum possible PTSS supported by platform.
-            auto maxPTSS = kernel.fg.builder->getMaxPTSS();
-            jitInfo->spillMemUsed = maxPTSS;
-
-            // reserve spillMemUsed #bytes at upper end of PTSS
-            kernel.getGTPinData()->setScratchNextFree(maxPTSS - kernel.getGTPinData()->getNumBytesScratchUse());
-        }
-        else {
+            // reserve spillMemUsed #bytes before 8kb boundary
+            kernel.getGTPinData()->setScratchNextFree(8*1024 - kernel.getGTPinData()->getNumBytesScratchUse());
+        } else {
             jitInfo->spillMemUsed = spillMemUsed;
             kernel.getGTPinData()->setScratchNextFree(spillMemUsed);
         }

visa/HWCaps.inc

@@ -850,16 +850,4 @@ SPDX-License-Identifier: MIT
    {
        return getPlatform() <= GENX_TGLLP;
    }
-
-   unsigned int getMaxPTSS() const
-   {
-      if (getPlatform() >= GENX_TGLLP)
-      {
-         // Max PTSS supported is 256kb
-         return 256 * 1024;
-      }
-
-      // Max PTSS supported is 2MB
-      return 2 * 1024 * 1024;
-   }
    // end HW capabilities