Handle implict read & written registers

dyninst · Sep 16, 2019 · e723bed · e723bed
1 parent 2dfdb68
commit e723bed
Showing 1 changed file with 27 additions and 0 deletions.
diff --git a/instructionAPI/src/InstructionDecoder-Capstone-x86.C b/instructionAPI/src/InstructionDecoder-Capstone-x86.C
@@ -1,5 +1,7 @@
 #include "InstructionDecoder-Capstone.h"
 
+using std::make_pair;
+
 namespace Dyninst {
 
 namespace InstructionAPI {
@@ -111,6 +113,31 @@ void InstructionDecoder_Capstone::decodeOperands_x86(const Instruction* insn, cs
             fprintf(stderr, "Unhandled capstone operand type %d\n", operand->type);
         }
     }
+
+    // The key is a Capstone register enum
+    // The value is a pair of boolean, where the first represnet whether read or not
+    // and the second one represents whether written or not
+    std::map< uint16_t, std::pair<bool, bool> > implicitRegs;
+    for (int i = 0; i < d->regs_read_count; ++i) {
+        implicitRegs.insert(make_pair(d->regs_read[i], make_pair(true, false)));
+    }
+    for (int i = 0; i < d->regs_write_count; ++i) {
+        auto it = implicitRegs.find(d->regs_write[i]);
+        if (it == implicitRegs.end()) {
+            implicitRegs.insert(make_pair(d->regs_write[i], make_pair(false, true)));
+        } else {
+            it->second.second = true;
+        }
+    }
+
+    for (auto rit = implicitRegs.begin(); rit != implicitRegs.end(); ++rit) {
+        MachRegister reg = (this->*regTrans)((x86_reg)rit->first);
+        // Traditionally, instructionAPI only present individual flag fields,
+        // not the whole flag register
+        if (reg == x86::flags || reg == x86_64::flags) continue;
+        Expression::Ptr regAST = makeRegisterExpression(reg);
+        insn->appendOperand(regAST, rit->second.first, rit->second.second, true);
+    }
     if (err) fprintf(stderr, "\tinstruction %s\n", insn->format().c_str()); 
 
 }