[aarch64] Emit abs, min, and max instructions during lifting

Author: bdash

arch/arm64/arm64test.py

@@ -12725,7 +12725,56 @@
     (b'\x1F\x20\x03\xD5', 'LLIL_NOP()'), # nop, gets optimized from function
 ]
 
+# FEAT_CSSC integer min/max and absolute value (lifted to dedicated LLIL ops)
+tests_cssc = [
+    # smax    w0, w1, w2
+    (b'\x20\x60\xc2\x1a', 'LLIL_SET_REG.d(w0,LLIL_MAXS.d(LLIL_REG.d(w1),LLIL_REG.d(w2)))'),
+    # smax    x0, x1, x2
+    (b'\x20\x60\xc2\x9a', 'LLIL_SET_REG.q(x0,LLIL_MAXS.q(LLIL_REG.q(x1),LLIL_REG.q(x2)))'),
+    # umax    w0, w1, w2
+    (b'\x20\x64\xc2\x1a', 'LLIL_SET_REG.d(w0,LLIL_MAXU.d(LLIL_REG.d(w1),LLIL_REG.d(w2)))'),
+    # umax    x0, x1, x2
+    (b'\x20\x64\xc2\x9a', 'LLIL_SET_REG.q(x0,LLIL_MAXU.q(LLIL_REG.q(x1),LLIL_REG.q(x2)))'),
+    # smin    w0, w1, w2
+    (b'\x20\x68\xc2\x1a', 'LLIL_SET_REG.d(w0,LLIL_MINS.d(LLIL_REG.d(w1),LLIL_REG.d(w2)))'),
+    # smin    x0, x1, x2
+    (b'\x20\x68\xc2\x9a', 'LLIL_SET_REG.q(x0,LLIL_MINS.q(LLIL_REG.q(x1),LLIL_REG.q(x2)))'),
+    # umin    w0, w1, w2
+    (b'\x20\x6c\xc2\x1a', 'LLIL_SET_REG.d(w0,LLIL_MINU.d(LLIL_REG.d(w1),LLIL_REG.d(w2)))'),
+    # umin    x0, x1, x2
+    (b'\x20\x6c\xc2\x9a', 'LLIL_SET_REG.q(x0,LLIL_MINU.q(LLIL_REG.q(x1),LLIL_REG.q(x2)))'),
+    # abs     w0, w1
+    (b'\x20\x20\xc0\x5a', 'LLIL_SET_REG.d(w0,LLIL_ABS.d(LLIL_REG.d(w1)))'),
+    # abs     x0, x1
+    (b'\x20\x20\xc0\xda', 'LLIL_SET_REG.q(x0,LLIL_ABS.q(LLIL_REG.q(x1)))'),
+    # smax    w0, w1, #0x5
+    (b'\x20\x14\xc0\x11', 'LLIL_SET_REG.d(w0,LLIL_MAXS.d(LLIL_REG.d(w1),LLIL_CONST.d(0x5)))'),
+    # umin    w0, w1, #0x7
+    (b'\x20\x1c\xcc\x11', 'LLIL_SET_REG.d(w0,LLIL_MINU.d(LLIL_REG.d(w1),LLIL_CONST.d(0x7)))'),
+    # ctz     w0, w1
+    (b'\x20\x18\xc0\x5a', 'LLIL_SET_REG.d(w0,LLIL_CTZ.d(LLIL_REG.d(w1)))'),
+    # ctz     x0, x1
+    (b'\x20\x18\xc0\xda', 'LLIL_SET_REG.q(x0,LLIL_CTZ.q(LLIL_REG.q(x1)))'),
+    # cnt     w0, w1 (FEAT_CSSC scalar population count)
+    (b'\x20\x1c\xc0\x5a', 'LLIL_SET_REG.d(w0,LLIL_POPCNT.d(LLIL_REG.d(w1)))'),
+    # cnt     x0, x1 (FEAT_CSSC scalar population count)
+    (b'\x20\x1c\xc0\xda', 'LLIL_SET_REG.q(x0,LLIL_POPCNT.q(LLIL_REG.q(x1)))'),
+
+    # Vector/SVE forms of these mnemonics are not FEAT_CSSC scalar ops and must not be lifted
+    # as whole-register scalar operations. The NEON cnt has a per-element intrinsic; the others
+    # have no native scalar representation and are left unimplemented.
+    # cnt     v0.8b, v1.8b
+    (b'\x20\x58\x20\x0e', 'LLIL_INTRINSIC([v0],_PopulationCount,[LLIL_REG.o(v1)])'),
+    # cnt     v0.16b, v1.16b
+    (b'\x20\x58\x20\x4e', 'LLIL_INTRINSIC([v0],_PopulationCount,[LLIL_REG.o(v1)])'),
+    # abs     v0.8b, v1.8b
+    (b'\x20\xb8\x20\x0e', 'LLIL_UNIMPL()'),
+    # abs     v0.2d, v1.2d
+    (b'\x20\xb8\xe0\x4e', 'LLIL_UNIMPL()'),
+]
+
 test_cases = \
+	tests_cssc + \
 	tests_shll + \
 	tests_udf + \
 	tests_pac + \

arch/arm64/il.cpp

@@ -1329,12 +1329,19 @@ bool GetLowLevelILForInstruction(
 	switch (instr.operation)
 	{
 	case ARM64_ABS:
-	{
-		ExprId src = ILREG_O(operand2);
-		GenIfElse(il, il.CompareSignedLessThan(REGSZ_O(operand2), src, il.Const(REGSZ_O(operand2), 0)),
-			ILSETREG_O(operand1, il.Neg(REGSZ_O(operand2), src)), ILSETREG_O(operand1, src));
+		switch (instr.encoding)
+		{
+		case ENC_ABS_32_DP_1SRC:
+		case ENC_ABS_64_DP_1SRC:
+			// FEAT_CSSC scalar absolute value on a general-purpose register
+			il.AddInstruction(ILSETREG_O(operand1, il.AbsoluteValue(REGSZ_O(operand2), ILREG_O(operand2))));
+			break;
+		default:
+			// The NEON and SVE forms are per-element absolute values, which have no native scalar
+			// representation
+			il.AddInstruction(il.Unimplemented());
+		}
 		break;
-	}
 	case ARM64_ADD:
 		switch (instr.encoding)
 		{
@@ -4004,8 +4011,7 @@ bool GetLowLevelILForInstruction(
 			return true;
 		}
 
-		GenIfElse(il, il.CompareSignedGreaterThan(REGSZ_O(operand2), op2, op3), ILSETREG_O(operand1, op2),
-			ILSETREG_O(operand1, op3));
+		il.AddInstruction(ILSETREG_O(operand1, il.MaxSigned(REGSZ_O(operand2), op2, op3)));
 		break;
 	}
 	case ARM64_SMIN:
@@ -4028,8 +4034,7 @@ bool GetLowLevelILForInstruction(
 			return true;
 		}
 
-		GenIfElse(il, il.CompareSignedLessThan(REGSZ_O(operand2), op2, op3), ILSETREG_O(operand1, op2),
-			ILSETREG_O(operand1, op3));
+		il.AddInstruction(ILSETREG_O(operand1, il.MinSigned(REGSZ_O(operand2), op2, op3)));
 		break;
 	}
 	case ARM64_UDIV:
@@ -4064,8 +4069,7 @@ bool GetLowLevelILForInstruction(
 			return true;
 		}
 
-		GenIfElse(il, il.CompareUnsignedGreaterThan(REGSZ_O(operand2), op2, op3), ILSETREG_O(operand1, op2),
-			ILSETREG_O(operand1, op3));
+		il.AddInstruction(ILSETREG_O(operand1, il.MaxUnsigned(REGSZ_O(operand2), op2, op3)));
 		break;
 	}
 	case ARM64_UMIN:
@@ -4088,8 +4092,7 @@ bool GetLowLevelILForInstruction(
 			return true;
 		}
 
-		GenIfElse(il, il.CompareUnsignedLessThan(REGSZ_O(operand2), op2, op3), ILSETREG_O(operand1, op2),
-			ILSETREG_O(operand1, op3));
+		il.AddInstruction(ILSETREG_O(operand1, il.MinUnsigned(REGSZ_O(operand2), op2, op3)));
 		break;
 	}
 	case ARM64_UBFIZ: