Add decodeOpcode

dyninst · Dec 14, 2023 · ec3683b · ec3683b
1 parent 433cb1d
commit ec3683b
Showing 1 changed file with 26 additions and 1 deletion.
diff --git a/instructionAPI/src/x86/decoder.C b/instructionAPI/src/x86/decoder.C
@@ -3,7 +3,11 @@
 
 #include "capstone/capstone.h"
 #include "capstone/x86.h"
+
+#include "x86/decoder.h"
+#include "x86/register-xlat.h"
 #include "mnemonic-xlat.h"
+#include "debug.h"
 
 namespace Dyninst { namespace InstructionAPI {
 
@@ -43,7 +47,28 @@ namespace Dyninst { namespace InstructionAPI {
   }
 
   void x86_decoder::doDelayedDecode(Instruction const*) {}
-  void x86_decoder::decodeOpcode(InstructionDecoder::buffer&) {}
+
+  void x86_decoder::decodeOpcode(InstructionDecoder::buffer& buf) {
+    auto* code = buf.start;
+    size_t codeSize = buf.end - buf.start;
+    uint64_t cap_addr = 0;
+
+    // We want this to be as fast as possible, so don't have Capstone provide all details.
+    auto &dis = dis_without_detail;
+
+    // The iterator form of disassembly allows reuse of the instruction object, reducing
+    // the number of memory allocations.
+    if(!cs_disasm_iter(dis.handle, &code, &codeSize, &cap_addr, dis.insn)) {
+      decode_printf("Failed to disassemble instruction at %p: %s\n", code, cs_strerror(cs_errno(dis.handle)));
+      m_Operation = Operation(e_No_Entry, "INVALID", m_Arch);
+      return;
+    }
+
+    entryID e = x86::translate_opcode(static_cast<x86_insn>(dis.insn->id));
+    m_Operation = Operation(e, dis.insn->mnemonic, m_Arch);
+    buf.start += dis.insn->size;
+  }
+
   bool x86_decoder::decodeOperands(Instruction const*) { return true; }
 
 }}