Simplify binary translation mappings, avoid some allocations

fwsGonzo · Oct 22, 2023 · f76774f · f76774f
1 parent c56f852
commit f76774f
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Showing 3 changed files with 10 additions and 9 deletions.
diff --git a/lib/libriscv/decoded_exec_segment.hpp b/lib/libriscv/decoded_exec_segment.hpp
@@ -52,6 +52,7 @@ namespace riscv
 #ifdef RISCV_BINARY_TRANSLATION
 		bool is_binary_translated() const noexcept { return m_bintr_dl != nullptr; }
 		void set_binary_translated(void* dl) const { m_bintr_dl = dl; }
+		void reserve_mappings(size_t mappings) { m_translator_mappings.reserve(mappings); }
 		void add_mapping(instruction_handler<W> handler) { m_translator_mappings.push_back(handler); }
 		instruction_handler<W> mapping_at(unsigned i) const { return m_translator_mappings.at(i); }
 #else

diff --git a/lib/libriscv/decoder_cache.cpp b/lib/libriscv/decoder_cache.cpp
@@ -266,6 +266,8 @@ namespace riscv
 		// When compressed instructions are enabled, many decoder
 		// entries are illegal because they between instructions.
 		bool was_full_instruction = true;
+		[[maybe_unused]] const auto block_ending_bytecode =
+			CPU<W>::computed_index_for(RV32_INSTR_BLOCK_END);
 
 		/* Generate all instruction pointers for executable code.
 		   Cannot step outside of this area when pregen is enabled,
@@ -283,14 +285,11 @@ namespace riscv
 			rv32i_instruction rewritten = instruction;
 
 #ifdef RISCV_BINARY_TRANSLATION
-			if (exec.is_binary_translated()) {
-				if (entry.isset()) {
-					// With translator ops we pretend the original opcode is JAL,
-					// which breaks the block-finding loop. In all cases, continue.
-					entry.set_bytecode(CPU<W>::computed_index_for(RV32_INSTR_BLOCK_END));
-					dst += 4;
-					continue;
-				}
+			// With translator ops we pretend the original opcode is JAL,
+			// which ends the block-finding loop.
+			if (entry.get_bytecode() == block_ending_bytecode) {
+				dst += 4;
+				continue;
 			}
 #endif // RISCV_BINARY_TRANSLATION
 

diff --git a/lib/libriscv/tr_translate.cpp b/lib/libriscv/tr_translate.cpp
@@ -429,12 +429,13 @@ void CPU<W>::activate_dylib(DecodedExecuteSegment<W>& exec, void* dylib) const
 
 	// Apply mappings to decoder cache
 	const auto nmappings = *no_mappings;
+	exec.reserve_mappings(nmappings);
 	for (size_t i = 0; i < nmappings; i++) {
 		exec.add_mapping(mappings[i].handler);
 		if (mappings[i].handler != nullptr) {
 			auto& entry = decoder_entry_at(exec, mappings[i].addr);
-			entry.m_handler = 0xFF;
 			entry.instr = i;
+			entry.set_bytecode(CPU<W>::computed_index_for(RV32_INSTR_BLOCK_END));
 		}
 	}