8293770: RISC-V: Reuse runtime call trampolines

Co-authored-by: zifeihan <caogui@iscas.ac.cn>
Reviewed-by: fyang, shade

src/hotspot/cpu/riscv/codeBuffer_riscv.cpp

@@ -27,6 +27,56 @@
 #include "asm/codeBuffer.inline.hpp"
 #include "asm/macroAssembler.hpp"
 
-bool CodeBuffer::pd_finalize_stubs() {
-  return emit_shared_stubs_to_interp<MacroAssembler>(this, _shared_stub_to_interp_requests);
+void CodeBuffer::share_trampoline_for(address dest, int caller_offset) {
+  if (_shared_trampoline_requests == nullptr) {
+    constexpr unsigned init_size = 8;
+    constexpr unsigned max_size  = 256;
+    _shared_trampoline_requests = new SharedTrampolineRequests(init_size, max_size);
+  }
+
+  bool created;
+  Offsets* offsets = _shared_trampoline_requests->put_if_absent(dest, &created);
+  if (created) {
+    _shared_trampoline_requests->maybe_grow();
+  }
+  offsets->add(caller_offset);
+  _finalize_stubs = true;
+}
+
+static bool emit_shared_trampolines(CodeBuffer* cb, CodeBuffer::SharedTrampolineRequests* requests) {
+  if (requests == nullptr) {
+    return true;
+  }
+
+  MacroAssembler masm(cb);
+
+  bool p_succeeded = true;
+  auto emit = [&](address dest, const CodeBuffer::Offsets &offsets) {
+    masm.set_code_section(cb->stubs());
+    masm.align(wordSize, NativeCallTrampolineStub::data_offset);
+
+    LinkedListIterator<int> it(offsets.head());
+    int offset = *it.next();
+    for (; !it.is_empty(); offset = *it.next()) {
+      masm.relocate(trampoline_stub_Relocation::spec(cb->insts()->start() + offset));
+    }
+    masm.set_code_section(cb->insts());
+
+    address stub = masm.emit_trampoline_stub(offset, dest);
+    if (stub == nullptr) {
+      ciEnv::current()->record_failure("CodeCache is full");
+      p_succeeded = false;
+    }
+
+    return p_succeeded;
+  };
+
+  requests->iterate(emit);
+
+  return p_succeeded;
+}
+
+bool CodeBuffer::pd_finalize_stubs() {
+  return emit_shared_stubs_to_interp<MacroAssembler>(this, _shared_stub_to_interp_requests)
+         && emit_shared_trampolines(this, _shared_trampoline_requests);
 }

src/hotspot/cpu/riscv/codeBuffer_riscv.hpp

@@ -35,4 +35,6 @@ public:
   void flush_bundle(bool start_new_bundle) {}
   static constexpr bool supports_shared_stubs() { return true; }
 
+  void share_trampoline_for(address dest, int caller_offset);
+
 #endif // CPU_RISCV_CODEBUFFER_RISCV_HPP

src/hotspot/cpu/riscv/macroAssembler_riscv.cpp

@@ -2801,6 +2801,8 @@ address MacroAssembler::trampoline_call(Address entry) {
          entry.rspec().type() == relocInfo::static_call_type ||
          entry.rspec().type() == relocInfo::virtual_call_type, "wrong reloc type");
 
+  address target = entry.target();
+
   // We need a trampoline if branches are far.
   if (far_branches()) {
     bool in_scratch_emit_size = false;
@@ -2813,12 +2815,18 @@ address MacroAssembler::trampoline_call(Address entry) {
        Compile::current()->output()->in_scratch_emit_size());
 #endif
     if (!in_scratch_emit_size) {
-      address stub = emit_trampoline_stub(offset(), entry.target());
-      if (stub == NULL) {
-        postcond(pc() == badAddress);
-        return NULL; // CodeCache is full
+      if (entry.rspec().type() == relocInfo::runtime_call_type) {
+        assert(CodeBuffer::supports_shared_stubs(), "must support shared stubs");
+        code()->share_trampoline_for(entry.target(), offset());
+      } else {
+        address stub = emit_trampoline_stub(offset(), target);
+        if (stub == NULL) {
+          postcond(pc() == badAddress);
+          return NULL; // CodeCache is full
+        }
       }
     }
+    target = pc();
   }
 
   address call_pc = pc();
@@ -2828,11 +2836,7 @@ address MacroAssembler::trampoline_call(Address entry) {
   }
 #endif
   relocate(entry.rspec());
-  if (!far_branches()) {
-    jal(entry.target());
-  } else {
-    jal(pc());
-  }
+  jal(target);
 
   postcond(pc() != badAddress);
   return call_pc;

test/hotspot/jtreg/compiler/sharedstubs/SharedTrampolineTest.java

@@ -28,7 +28,8 @@
  * @bug 8280152
  * @library /test/lib
  *
- * @requires vm.debug & os.arch=="aarch64"
+ * @requires os.arch=="aarch64" | os.arch=="riscv64"
+ * @requires vm.debug
  *
  * @run driver compiler.sharedstubs.SharedTrampolineTest
  */