Add support for Tzcnt and Lzcnt

avast · Apr 29, 2024 · fd1b568 · fd1b568
1 parent 58b041e
commit fd1b568
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Showing 3 changed files with 27 additions and 2 deletions.
diff --git a/src/capstone2llvmir/x86/x86.cpp b/src/capstone2llvmir/x86/x86.cpp
@@ -3364,6 +3364,7 @@ void Capstone2LlvmIrTranslatorX86_impl::translateShiftX(cs_insn* i, cs_x86* xi,
 		case X86_INS_SHR: return llvm::Instruction::BinaryOps::LShr;
 		case X86_INS_SAR: return llvm::Instruction::BinaryOps::AShr;
 		case X86_INS_SHL: return llvm::Instruction::BinaryOps::Shl;
+		default: assert(false);
 		}
 	}();
 
@@ -5444,5 +5445,28 @@ void Capstone2LlvmIrTranslatorX86_impl::translateRdtscp(cs_insn* i, cs_x86* xi,
 	storeRegister(X86_REG_ECX, irb.CreateExtractValue(c, {2}), irb);
 }
 
+void Capstone2LlvmIrTranslatorX86_impl::translateTzcntOrLzcnt(cs_insn* i, cs_x86* xi, llvm::IRBuilder<>& irb)
+{
+	EXPECT_IS_BINARY(i, xi, irb);
+
+	std::tie(op0, op1) = loadOpBinary(xi, irb);
+
+	storeRegister(X86_REG_CF, generateZeroFlag(op1, irb), irb);
+
+	op0 = irb.CreateIntrinsic(
+		i->id == X86_INS_LZCNT ? llvm::Intrinsic::ctlz : llvm::Intrinsic::cttz,
+		{op1->getType()},
+		{op1, irb.getFalse()});
+
+	storeRegister(X86_REG_OF, irb.getFalse(), irb); // undef
+	storeRegister(X86_REG_SF, irb.getFalse(), irb); // undef
+	storeRegister(X86_REG_PF, irb.getFalse(), irb); // undef
+	storeRegister(X86_REG_AF, irb.getFalse(), irb); // undef
+
+	storeRegister(X86_REG_ZF, generateZeroFlag(op0, irb), irb);
+
+	storeOp(xi->operands[0], op0, irb);
+}
+
 } // namespace capstone2llvmir
 } // namespace retdec
diff --git a/src/capstone2llvmir/x86/x86_impl.h b/src/capstone2llvmir/x86/x86_impl.h
@@ -354,6 +354,7 @@ class Capstone2LlvmIrTranslatorX86_impl :
 		void translateXchg(cs_insn* i, cs_x86* xi, llvm::IRBuilder<>& irb);
 		void translateXlatb(cs_insn* i, cs_x86* xi, llvm::IRBuilder<>& irb);
 		void translateXor(cs_insn* i, cs_x86* xi, llvm::IRBuilder<>& irb);
+		void translateTzcntOrLzcnt(cs_insn* i, cs_x86* xi, llvm::IRBuilder<>& irb);
 };
 
 } // namespace capstone2llvmir

diff --git a/src/capstone2llvmir/x86/x86_init.cpp b/src/capstone2llvmir/x86/x86_init.cpp
@@ -966,7 +966,7 @@ Capstone2LlvmIrTranslatorX86_impl::_i2fm =
 		{X86_INS_LSS, &Capstone2LlvmIrTranslatorX86_impl::translateLoadFarPtr},
 		{X86_INS_LTR, nullptr},
 		{X86_INS_XADD, &Capstone2LlvmIrTranslatorX86_impl::translateAdd},
-		{X86_INS_LZCNT, nullptr},
+		{X86_INS_LZCNT, &Capstone2LlvmIrTranslatorX86_impl::translateTzcntOrLzcnt},
 		{X86_INS_MASKMOVDQU, nullptr},
 		{X86_INS_MAXPD, nullptr},
 		{X86_INS_MAXPS, nullptr},
@@ -1320,7 +1320,7 @@ Capstone2LlvmIrTranslatorX86_impl::_i2fm =
 		{X86_INS_TEST, &Capstone2LlvmIrTranslatorX86_impl::translateAnd},
 		{X86_INS_UD2, &Capstone2LlvmIrTranslatorX86_impl::translateNop},
 		{X86_INS_FTST, &Capstone2LlvmIrTranslatorX86_impl::translateFucomPop},
-		{X86_INS_TZCNT, nullptr},
+		{X86_INS_TZCNT, &Capstone2LlvmIrTranslatorX86_impl::translateTzcntOrLzcnt},
 		{X86_INS_TZMSK, nullptr},
 		{X86_INS_FUCOMPI, &Capstone2LlvmIrTranslatorX86_impl::translateFucomPop},
 		{X86_INS_FUCOMI, &Capstone2LlvmIrTranslatorX86_impl::translateFucomPop},