8346832: runtime/CompressedOops/CompressedCPUSpecificClassSpaceReservation.java fails on RISC-V

Reviewed-by: stuefe, fjiang

Author: RealFYang

src/hotspot/cpu/riscv/compressedKlass_riscv.cpp

@@ -31,7 +31,7 @@ char* CompressedKlassPointers::reserve_address_space_for_compressed_classes(size
 
   char* result = nullptr;
 
-  // RiscV loads a 64-bit immediate in up to four separate steps, splitting it into four different sections
+  // RISC-V loads a 64-bit immediate in up to four separate steps, splitting it into four different sections
   // (two 32-bit sections, each split into two subsections of 20/12 bits).
   //
   // 63 ....... 44 43 ... 32 31 ....... 12 11 ... 0
@@ -51,11 +51,6 @@ char* CompressedKlassPointers::reserve_address_space_for_compressed_classes(size
   //   with one instruction (2)
   result = reserve_address_space_for_unscaled_encoding(size, aslr);
 
-  // Failing that, attempt to reserve for base=zero shift>0
-  if (result == nullptr && optimize_for_zero_base) {
-    result = reserve_address_space_for_zerobased_encoding(size, aslr);
-  }
-
   // Failing that, optimize for case (3) - a base with only bits set between [32-44)
   if (result == nullptr) {
     const uintptr_t from = nth_bit(32);

test/hotspot/jtreg/runtime/CompressedOops/CompressedCPUSpecificClassSpaceReservation.java

@@ -85,15 +85,8 @@ private static void do_test(boolean CDS) throws IOException {
             output.shouldContain(tryReserveFor16bitMoveIntoQ3);
         } else if (Platform.isRISCV64()) {
             output.shouldContain(tryReserveForUnscaled); // unconditionally
-            if (CDS) {
-                output.shouldNotContain(tryReserveForZeroBased);
-                // bits 32..44
-                output.shouldContain("reserve_between (range [0x0000000100000000-0x0000100000000000)");
-            } else {
-                output.shouldContain(tryReserveForZeroBased);
-                // bits 32..44, but not lower than zero-based limit
-                output.shouldContain("reserve_between (range [0x0000000800000000-0x0000100000000000)");
-            }
+            // bits 32..44
+            output.shouldContain("reserve_between (range [0x0000000100000000-0x0000100000000000)");
             // bits 44..64
             output.shouldContain("reserve_between (range [0x0000100000000000-0xffffffffffffffff)");
         } else if (Platform.isS390x()) {