do this by shifting the bit being tested to the low-order bit and
masking the result with the constant 1. If the condition was EQ,
we xor it with 1. This does not require an scc insn and is faster
- than an scc insn even if we have it. */
+ than an scc insn even if we have it.
+
+ The code to make this transformation was moved into fold_single_bit_test,
+ so we just call into the folder and expand its result. */
if ((code == NE || code == EQ)
&& TREE_CODE (arg0) == BIT_AND_EXPR && integer_zerop (arg1)
&& integer_pow2p (TREE_OPERAND (arg0, 1)))
- {
- tree inner = TREE_OPERAND (arg0, 0);
- int bitnum = tree_log2 (TREE_OPERAND (arg0, 1));
- int ops_unsignedp;
-
- /* If INNER is a right shift of a constant and it plus BITNUM does
- not overflow, adjust BITNUM and INNER. */
-
- if (TREE_CODE (inner) == RSHIFT_EXPR
- && TREE_CODE (TREE_OPERAND (inner, 1)) == INTEGER_CST
- && TREE_INT_CST_HIGH (TREE_OPERAND (inner, 1)) == 0
- && bitnum < TYPE_PRECISION (type)
- && 0 > compare_tree_int (TREE_OPERAND (inner, 1),
- bitnum - TYPE_PRECISION (type)))
- {
- bitnum += TREE_INT_CST_LOW (TREE_OPERAND (inner, 1));
- inner = TREE_OPERAND (inner, 0);
- }
-
- /* If we are going to be able to omit the AND below, we must do our
- operations as unsigned. If we must use the AND, we have a choice.
- Normally unsigned is faster, but for some machines signed is. */
- ops_unsignedp = (bitnum == TYPE_PRECISION (type) - 1 ? 1
-#ifdef LOAD_EXTEND_OP
- : (LOAD_EXTEND_OP (operand_mode) == SIGN_EXTEND ? 0 : 1)
-#else
- : 1
-#endif
- );
-
- if (! get_subtarget (subtarget)
- || GET_MODE (subtarget) != operand_mode
- || ! safe_from_p (subtarget, inner, 1))
- subtarget = 0;
-
- op0 = expand_expr (inner, subtarget, VOIDmode, 0);
-
- if (bitnum != 0)
- op0 = expand_shift (RSHIFT_EXPR, operand_mode, op0,
- size_int (bitnum), subtarget, ops_unsignedp);
-
- if (GET_MODE (op0) != mode)
- op0 = convert_to_mode (mode, op0, ops_unsignedp);
-
- if ((code == EQ && ! invert) || (code == NE && invert))
- op0 = expand_binop (mode, xor_optab, op0, const1_rtx, subtarget,
- ops_unsignedp, OPTAB_LIB_WIDEN);
-
- /* Put the AND last so it can combine with more things. */
- if (bitnum != TYPE_PRECISION (type) - 1)
- op0 = expand_and (mode, op0, const1_rtx, subtarget);
-
- return op0;
- }
+ return expand_expr (fold_single_bit_test (code == NE ? NE_EXPR : EQ_EXPR,
+ arg0, arg1, type),
+ target, VOIDmode, EXPAND_NORMAL);
/* Now see if we are likely to be able to do this. Return if not. */
if (! can_compare_p (code, operand_mode, ccp_store_flag))
return NULL_TREE;
}
+/* If CODE with arguments ARG0 and ARG1 represents a single bit
+ equality/inequality test, then return a simplified form of
+ the test using shifts and logical operations. Otherwise return
+ NULL. TYPE is the desired result type. */
+
+tree
+fold_single_bit_test (code, arg0, arg1, result_type)
+ enum tree_code code;
+ tree arg0;
+ tree arg1;
+ tree result_type;
+{
+ /* If this is a TRUTH_NOT_EXPR, it may have a single bit test inside
+ operand 0. */
+ if (code == TRUTH_NOT_EXPR)
+ {
+ code = TREE_CODE (arg0);
+ if (code != NE_EXPR && code != EQ_EXPR)
+ return NULL_TREE;
+
+ /* Extract the arguments of the EQ/NE. */
+ arg1 = TREE_OPERAND (arg0, 1);
+ arg0 = TREE_OPERAND (arg0, 0);
+
+ /* This requires us to invert the code. */
+ code = (code == EQ_EXPR ? NE_EXPR : EQ_EXPR);
+ }
+
+ /* If this is testing a single bit, we can optimize the test. */
+ if ((code == NE_EXPR || code == EQ_EXPR)
+ && TREE_CODE (arg0) == BIT_AND_EXPR && integer_zerop (arg1)
+ && integer_pow2p (TREE_OPERAND (arg0, 1)))
+ {
+ tree inner = TREE_OPERAND (arg0, 0);
+ tree type = TREE_TYPE (arg0);
+ int bitnum = tree_log2 (TREE_OPERAND (arg0, 1));
+ enum machine_mode operand_mode = TYPE_MODE (type);
+ int ops_unsigned;
+ tree signed_type, unsigned_type;
+ tree arg00;
+
+ /* If we have (A & C) != 0 where C is the sign bit of A, convert
+ this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
+ arg00 = sign_bit_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg0, 1));
+ if (arg00 != NULL_TREE)
+ {
+ tree stype = (*lang_hooks.types.signed_type) (TREE_TYPE (arg00));
+ return fold (build (code == EQ_EXPR ? GE_EXPR : LT_EXPR, type,
+ convert (stype, arg00),
+ convert (stype, integer_zero_node)));
+ }
+
+ /* Otherwise we have (A & C) != 0 where C is a single bit,
+ convert that into ((A >> C2) & 1). Where C2 = log2(C).
+ Similarly for (A & C) == 0. */
+
+ /* If INNER is a right shift of a constant and it plus BITNUM does
+ not overflow, adjust BITNUM and INNER. */
+ if (TREE_CODE (inner) == RSHIFT_EXPR
+ && TREE_CODE (TREE_OPERAND (inner, 1)) == INTEGER_CST
+ && TREE_INT_CST_HIGH (TREE_OPERAND (inner, 1)) == 0
+ && bitnum < TYPE_PRECISION (type)
+ && 0 > compare_tree_int (TREE_OPERAND (inner, 1),
+ bitnum - TYPE_PRECISION (type)))
+ {
+ bitnum += TREE_INT_CST_LOW (TREE_OPERAND (inner, 1));
+ inner = TREE_OPERAND (inner, 0);
+ }
+
+ /* If we are going to be able to omit the AND below, we must do our
+ operations as unsigned. If we must use the AND, we have a choice.
+ Normally unsigned is faster, but for some machines signed is. */
+ ops_unsigned = (bitnum == TYPE_PRECISION (type) - 1 ? 1
+#ifdef LOAD_EXTEND_OP
+ : (LOAD_EXTEND_OP (operand_mode) == SIGN_EXTEND ? 0 : 1)
+#else
+ : 1
+#endif
+ );
+
+ signed_type = (*lang_hooks.types.type_for_mode) (operand_mode, 0);
+ unsigned_type = (*lang_hooks.types.type_for_mode) (operand_mode, 1);
+
+ if (bitnum != 0)
+ inner = build (RSHIFT_EXPR, ops_unsigned ? unsigned_type : signed_type,
+ inner, size_int (bitnum));
+
+ if (code == EQ_EXPR)
+ inner = build (BIT_XOR_EXPR, ops_unsigned ? unsigned_type : signed_type,
+ inner, integer_one_node);
+
+ /* Put the AND last so it can combine with more things. */
+ if (bitnum != TYPE_PRECISION (type) - 1)
+ inner = build (BIT_AND_EXPR, ops_unsigned ? unsigned_type : signed_type,
+ inner, integer_one_node);
+
+ /* Make sure to return the proper type. */
+ if (TREE_TYPE (inner) != result_type)
+ inner = convert (result_type, inner);
+
+ return inner;
+ }
+ return NULL_TREE;
+}
+
/* Perform constant folding and related simplification of EXPR.
The related simplifications include x*1 => x, x*0 => 0, etc.,
and application of the associative law.
tem = invert_truthvalue (arg0);
/* Avoid infinite recursion. */
if (TREE_CODE (tem) == TRUTH_NOT_EXPR)
- return t;
+ {
+ tem = fold_single_bit_test (code, arg0, arg1, type);
+ if (tem)
+ return tem;
+ return t;
+ }
return convert (type, tem);
case TRUTH_ANDIF_EXPR:
return fold (build (code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type,
arg0, integer_zero_node));
- /* If we have (A & C) != 0 where C is the sign bit of A, convert
- this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
- if ((code == EQ_EXPR || code == NE_EXPR)
- && TREE_CODE (arg0) == BIT_AND_EXPR
- && integer_zerop (arg1))
- {
- tree arg00 = sign_bit_p (TREE_OPERAND (arg0, 0),
- TREE_OPERAND (arg0, 1));
- if (arg00 != NULL_TREE)
- {
- tree stype = (*lang_hooks.types.signed_type) (TREE_TYPE (arg00));
- return fold (build (code == EQ_EXPR ? GE_EXPR : LT_EXPR, type,
- convert (stype, arg00),
- convert (stype, integer_zero_node)));
- }
- }
+ /* If we have (A & C) != 0 or (A & C) == 0 and C is a power of
+ 2, then fold the expression into shifts and logical operations. */
+ tem = fold_single_bit_test (code, arg0, arg1, type);
+ if (tem)
+ return tem;
/* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
and similarly for >= into !=. */
projects / gcc.git / commitdiff