Fix the address sub register number which can only be even value which is used as extend descriptor in send

Fix the address sub register number which can only be even value which is
used as extend descriptor in send. This is a encoding restriction.

Author: fangliu2020

visa/BuildIRImpl.cpp

@@ -2639,8 +2639,12 @@ G4_InstSend *IR_Builder::createLscSendInst(
         // The payload keeps reusing fixed a0.2 serializes loads. To improve the
         // the performance issue caused by this, we create temp address
         // variables and let RA to assign to spread out a0 usage.
-        if (getOption(vISA_dynamicAddrForExDescInLscSend))
+        if (useDynamicAddrForExDesc()) {
           addrDecl = createTempAddress(1);
+          // Due to encoding restriction, address sub register number must be
+          // even value if it's used as extended message descriptor.
+          addrDecl->setSubRegAlign(Four_Word);
+        }
         G4_DstRegRegion *addrDstOpnd = createDstRegRegion(addrDecl, 1);
         if ((addrType == LSC_ADDR_TYPE_BSS) || (addrType == LSC_ADDR_TYPE_SS)) {
           if (ssIdx == 0x0) {

visa/HWCaps.inc

@@ -919,4 +919,8 @@ bool needTGMDoubleFenceWA() const {
   return VISA_WA_CHECK(getPWaTable(), Wa_14021891663) &&
       getOption(vISA_TGMDoubleFenceWA);
 }
+
+bool useDynamicAddrForExDesc() const {
+  return getOption(vISA_dynamicAddrForExDescInLscSend);
+}
 // end HW capabilities