static int merge_ranges (int *, tree *, tree *, int, tree, tree, int, tree,
tree);
static tree fold_range_test (tree);
+static tree fold_cond_expr_with_comparison (tree, tree, tree);
static tree unextend (tree, int, int, tree);
static tree fold_truthop (enum tree_code, tree, tree, tree);
static tree optimize_minmax_comparison (tree);
return 1;
}
\f
+
+/* Subroutine of fold, looking inside expressions of the form
+ A op B ? A : C, where ARG0 is A op B and ARG2 is C. This
+ function is being used also to optimize A op B ? C : A, by
+ reversing the comparison first.
+
+ Return a folded expression whose code is not a COND_EXPR
+ anymore, or NULL_TREE if no folding opportunity is found. */
+
+static tree
+fold_cond_expr_with_comparison (tree type, tree arg0, tree arg2)
+{
+ enum tree_code comp_code = TREE_CODE (arg0);
+ tree arg00 = TREE_OPERAND (arg0, 0);
+ tree arg01 = TREE_OPERAND (arg0, 1);
+ tree tem;
+ STRIP_NOPS (arg2);
+
+ /* If we have A op 0 ? A : -A, consider applying the following
+ transformations:
+
+ A == 0? A : -A same as -A
+ A != 0? A : -A same as A
+ A >= 0? A : -A same as abs (A)
+ A > 0? A : -A same as abs (A)
+ A <= 0? A : -A same as -abs (A)
+ A < 0? A : -A same as -abs (A)
+
+ None of these transformations work for modes with signed
+ zeros. If A is +/-0, the first two transformations will
+ change the sign of the result (from +0 to -0, or vice
+ versa). The last four will fix the sign of the result,
+ even though the original expressions could be positive or
+ negative, depending on the sign of A.
+
+ Note that all these transformations are correct if A is
+ NaN, since the two alternatives (A and -A) are also NaNs. */
+ if ((FLOAT_TYPE_P (TREE_TYPE (arg01))
+ ? real_zerop (arg01)
+ : integer_zerop (arg01))
+ && TREE_CODE (arg2) == NEGATE_EXPR
+ && operand_equal_p (TREE_OPERAND (arg2, 0), arg00, 0))
+ switch (comp_code)
+ {
+ case EQ_EXPR:
+ return fold_convert (type, negate_expr (arg00));
+ case NE_EXPR:
+ return pedantic_non_lvalue (fold_convert (type, arg00));
+ case GE_EXPR:
+ case GT_EXPR:
+ if (TYPE_UNSIGNED (TREE_TYPE (arg00)))
+ arg00 = fold_convert (lang_hooks.types.signed_type
+ (TREE_TYPE (arg00)), arg00);
+ tem = fold (build1 (ABS_EXPR, TREE_TYPE (arg00), arg00));
+ return pedantic_non_lvalue (fold_convert (type, tem));
+ case LE_EXPR:
+ case LT_EXPR:
+ if (TYPE_UNSIGNED (TREE_TYPE (arg00)))
+ arg00 = fold_convert (lang_hooks.types.signed_type
+ (TREE_TYPE (arg00)), arg00);
+ tem = fold (build1 (ABS_EXPR, TREE_TYPE (arg00), arg00));
+ return negate_expr (fold_convert (type, tem));
+ default:
+ abort ();
+ }
+
+ /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
+ A == 0 ? A : 0 is always 0 unless A is -0. Note that
+ both transformations are correct when A is NaN: A != 0
+ is then true, and A == 0 is false. */
+
+ if (integer_zerop (arg01) && integer_zerop (arg2))
+ {
+ if (comp_code == NE_EXPR)
+ return pedantic_non_lvalue (fold_convert (type, arg00));
+ else if (comp_code == EQ_EXPR)
+ return pedantic_non_lvalue (fold_convert (type, integer_zero_node));
+ }
+
+ /* Try some transformations of A op B ? A : B.
+
+ A == B? A : B same as B
+ A != B? A : B same as A
+ A >= B? A : B same as max (A, B)
+ A > B? A : B same as max (B, A)
+ A <= B? A : B same as min (A, B)
+ A < B? A : B same as min (B, A)
+
+ As above, these transformations don't work in the presence
+ of signed zeros. For example, if A and B are zeros of
+ opposite sign, the first two transformations will change
+ the sign of the result. In the last four, the original
+ expressions give different results for (A=+0, B=-0) and
+ (A=-0, B=+0), but the transformed expressions do not.
+
+ The first two transformations are correct if either A or B
+ is a NaN. In the first transformation, the condition will
+ be false, and B will indeed be chosen. In the case of the
+ second transformation, the condition A != B will be true,
+ and A will be chosen.
+
+ The conversions to max() and min() are not correct if B is
+ a number and A is not. The conditions in the original
+ expressions will be false, so all four give B. The min()
+ and max() versions would give a NaN instead. */
+ if (operand_equal_for_comparison_p (arg01, arg2, arg00))
+ {
+ tree comp_op0 = arg00;
+ tree comp_op1 = arg01;
+ tree comp_type = TREE_TYPE (comp_op0);
+
+ /* Avoid adding NOP_EXPRs in case this is an lvalue. */
+ if (TYPE_MAIN_VARIANT (comp_type) == TYPE_MAIN_VARIANT (type))
+ {
+ comp_type = type;
+ comp_op0 = arg00;
+ comp_op1 = arg2;
+ }
+
+ switch (comp_code)
+ {
+ case EQ_EXPR:
+ return pedantic_non_lvalue (fold_convert (type, arg2));
+ case NE_EXPR:
+ return pedantic_non_lvalue (fold_convert (type, arg00));
+ case LE_EXPR:
+ case LT_EXPR:
+ /* In C++ a ?: expression can be an lvalue, so put the
+ operand which will be used if they are equal first
+ so that we can convert this back to the
+ corresponding COND_EXPR. */
+ if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg00))))
+ return pedantic_non_lvalue (
+ fold_convert (type, fold (build2 (MIN_EXPR, comp_type,
+ (comp_code == LE_EXPR
+ ? comp_op0 : comp_op1),
+ (comp_code == LE_EXPR
+ ? comp_op1 : comp_op0)))));
+ break;
+ case GE_EXPR:
+ case GT_EXPR:
+ if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg00))))
+ return pedantic_non_lvalue (
+ fold_convert (type, fold (build2 (MAX_EXPR, comp_type,
+ (comp_code == GE_EXPR
+ ? comp_op0 : comp_op1),
+ (comp_code == GE_EXPR
+ ? comp_op1 : comp_op0)))));
+ break;
+ default:
+ abort ();
+ }
+ }
+
+ /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
+ we might still be able to simplify this. For example,
+ if C1 is one less or one more than C2, this might have started
+ out as a MIN or MAX and been transformed by this function.
+ Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
+
+ if (INTEGRAL_TYPE_P (type)
+ && TREE_CODE (arg01) == INTEGER_CST
+ && TREE_CODE (arg2) == INTEGER_CST)
+ switch (comp_code)
+ {
+ case EQ_EXPR:
+ /* We can replace A with C1 in this case. */
+ arg00 = fold_convert (type, arg01);
+ return fold (build3 (COND_EXPR, type, arg0, arg00, arg2));
+
+ case LT_EXPR:
+ /* If C1 is C2 + 1, this is min(A, C2). */
+ if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
+ OEP_ONLY_CONST)
+ && operand_equal_p (arg01,
+ const_binop (PLUS_EXPR, arg2,
+ integer_one_node, 0),
+ OEP_ONLY_CONST))
+ return pedantic_non_lvalue (fold (build2 (MIN_EXPR,
+ type, arg00, arg2)));
+ break;
+
+ case LE_EXPR:
+ /* If C1 is C2 - 1, this is min(A, C2). */
+ if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
+ OEP_ONLY_CONST)
+ && operand_equal_p (arg01,
+ const_binop (MINUS_EXPR, arg2,
+ integer_one_node, 0),
+ OEP_ONLY_CONST))
+ return pedantic_non_lvalue (fold (build2 (MIN_EXPR,
+ type, arg00, arg2)));
+ break;
+
+ case GT_EXPR:
+ /* If C1 is C2 - 1, this is max(A, C2). */
+ if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
+ OEP_ONLY_CONST)
+ && operand_equal_p (arg01,
+ const_binop (MINUS_EXPR, arg2,
+ integer_one_node, 0),
+ OEP_ONLY_CONST))
+ return pedantic_non_lvalue (fold (build2 (MAX_EXPR,
+ type, arg00, arg2)));
+ break;
+
+ case GE_EXPR:
+ /* If C1 is C2 + 1, this is max(A, C2). */
+ if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
+ OEP_ONLY_CONST)
+ && operand_equal_p (arg01,
+ const_binop (PLUS_EXPR, arg2,
+ integer_one_node, 0),
+ OEP_ONLY_CONST))
+ return pedantic_non_lvalue (fold (build2 (MAX_EXPR,
+ type, arg00, arg2)));
+ break;
+ case NE_EXPR:
+ break;
+ default:
+ abort ();
+ }
+
+ return NULL_TREE;
+}
+
+
+\f
#ifndef RANGE_TEST_NON_SHORT_CIRCUIT
#define RANGE_TEST_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
#endif
/* If we have A op B ? A : C, we may be able to convert this to a
simpler expression, depending on the operation and the values
of B and C. Signed zeros prevent all of these transformations,
- for reasons given above each one. */
+ for reasons given above each one.
+ Also try swapping the arguments and inverting the conditional. */
if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
&& operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
arg1, TREE_OPERAND (arg0, 1))
&& !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
{
- tree arg2 = TREE_OPERAND (t, 2);
- enum tree_code comp_code = TREE_CODE (arg0);
-
- STRIP_NOPS (arg2);
-
- /* If we have A op 0 ? A : -A, consider applying the following
- transformations:
-
- A == 0? A : -A same as -A
- A != 0? A : -A same as A
- A >= 0? A : -A same as abs (A)
- A > 0? A : -A same as abs (A)
- A <= 0? A : -A same as -abs (A)
- A < 0? A : -A same as -abs (A)
-
- None of these transformations work for modes with signed
- zeros. If A is +/-0, the first two transformations will
- change the sign of the result (from +0 to -0, or vice
- versa). The last four will fix the sign of the result,
- even though the original expressions could be positive or
- negative, depending on the sign of A.
-
- Note that all these transformations are correct if A is
- NaN, since the two alternatives (A and -A) are also NaNs. */
- if ((FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 1)))
- ? real_zerop (TREE_OPERAND (arg0, 1))
- : integer_zerop (TREE_OPERAND (arg0, 1)))
- && TREE_CODE (arg2) == NEGATE_EXPR
- && operand_equal_p (TREE_OPERAND (arg2, 0), arg1, 0))
- switch (comp_code)
- {
- case EQ_EXPR:
- tem = fold_convert (TREE_TYPE (TREE_OPERAND (t, 1)), arg1);
- tem = fold_convert (type, negate_expr (tem));
- return pedantic_non_lvalue (tem);
- case NE_EXPR:
- return pedantic_non_lvalue (fold_convert (type, arg1));
- case GE_EXPR:
- case GT_EXPR:
- if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
- arg1 = fold_convert (lang_hooks.types.signed_type
- (TREE_TYPE (arg1)), arg1);
- arg1 = fold (build1 (ABS_EXPR, TREE_TYPE (arg1), arg1));
- return pedantic_non_lvalue (fold_convert (type, arg1));
- case LE_EXPR:
- case LT_EXPR:
- if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
- arg1 = fold_convert (lang_hooks.types.signed_type
- (TREE_TYPE (arg1)), arg1);
- arg1 = fold (build1 (ABS_EXPR, TREE_TYPE (arg1), arg1));
- arg1 = negate_expr (fold_convert (type, arg1));
- return pedantic_non_lvalue (arg1);
- default:
- abort ();
- }
-
- /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
- A == 0 ? A : 0 is always 0 unless A is -0. Note that
- both transformations are correct when A is NaN: A != 0
- is then true, and A == 0 is false. */
-
- if (integer_zerop (TREE_OPERAND (arg0, 1)) && integer_zerop (arg2))
- {
- if (comp_code == NE_EXPR)
- return pedantic_non_lvalue (fold_convert (type, arg1));
- else if (comp_code == EQ_EXPR)
- return pedantic_non_lvalue (fold_convert (type, integer_zero_node));
- }
+ tem = fold_cond_expr_with_comparison (type, arg0,
+ TREE_OPERAND (t, 2));
+ if (tem)
+ return tem;
+ }
- /* Try some transformations of A op B ? A : B.
-
- A == B? A : B same as B
- A != B? A : B same as A
- A >= B? A : B same as max (A, B)
- A > B? A : B same as max (B, A)
- A <= B? A : B same as min (A, B)
- A < B? A : B same as min (B, A)
-
- As above, these transformations don't work in the presence
- of signed zeros. For example, if A and B are zeros of
- opposite sign, the first two transformations will change
- the sign of the result. In the last four, the original
- expressions give different results for (A=+0, B=-0) and
- (A=-0, B=+0), but the transformed expressions do not.
-
- The first two transformations are correct if either A or B
- is a NaN. In the first transformation, the condition will
- be false, and B will indeed be chosen. In the case of the
- second transformation, the condition A != B will be true,
- and A will be chosen.
-
- The conversions to max() and min() are not correct if B is
- a number and A is not. The conditions in the original
- expressions will be false, so all four give B. The min()
- and max() versions would give a NaN instead. */
- if (operand_equal_for_comparison_p (TREE_OPERAND (arg0, 1),
- arg2, TREE_OPERAND (arg0, 0)))
+ if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
+ && operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
+ TREE_OPERAND (t, 2),
+ TREE_OPERAND (arg0, 1))
+ && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (t, 2)))))
+ {
+ tem = invert_truthvalue (arg0);
+ if (TREE_CODE_CLASS (TREE_CODE (tem)) == '<')
{
- tree comp_op0 = TREE_OPERAND (arg0, 0);
- tree comp_op1 = TREE_OPERAND (arg0, 1);
- tree comp_type = TREE_TYPE (comp_op0);
-
- /* Avoid adding NOP_EXPRs in case this is an lvalue. */
- if (TYPE_MAIN_VARIANT (comp_type) == TYPE_MAIN_VARIANT (type))
- {
- comp_type = type;
- comp_op0 = arg1;
- comp_op1 = arg2;
- }
-
- switch (comp_code)
- {
- case EQ_EXPR:
- return pedantic_non_lvalue (fold_convert (type, arg2));
- case NE_EXPR:
- return pedantic_non_lvalue (fold_convert (type, arg1));
- case LE_EXPR:
- case LT_EXPR:
- /* In C++ a ?: expression can be an lvalue, so put the
- operand which will be used if they are equal first
- so that we can convert this back to the
- corresponding COND_EXPR. */
- if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg1))))
- return pedantic_non_lvalue (fold_convert
- (type, fold (build2 (MIN_EXPR, comp_type,
- (comp_code == LE_EXPR
- ? comp_op0 : comp_op1),
- (comp_code == LE_EXPR
- ? comp_op1 : comp_op0)))));
- break;
- case GE_EXPR:
- case GT_EXPR:
- if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg1))))
- return pedantic_non_lvalue (fold_convert
- (type, fold (build2 (MAX_EXPR, comp_type,
- (comp_code == GE_EXPR
- ? comp_op0 : comp_op1),
- (comp_code == GE_EXPR
- ? comp_op1 : comp_op0)))));
- break;
- default:
- abort ();
- }
+ tem = fold_cond_expr_with_comparison (type, tem, arg1);
+ if (tem)
+ return tem;
}
-
- /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
- we might still be able to simplify this. For example,
- if C1 is one less or one more than C2, this might have started
- out as a MIN or MAX and been transformed by this function.
- Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
-
- if (INTEGRAL_TYPE_P (type)
- && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
- && TREE_CODE (arg2) == INTEGER_CST)
- switch (comp_code)
- {
- case EQ_EXPR:
- /* We can replace A with C1 in this case. */
- arg1 = fold_convert (type, TREE_OPERAND (arg0, 1));
- return fold (build3 (code, type, TREE_OPERAND (t, 0), arg1,
- TREE_OPERAND (t, 2)));
-
- case LT_EXPR:
- /* If C1 is C2 + 1, this is min(A, C2). */
- if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
- OEP_ONLY_CONST)
- && operand_equal_p (TREE_OPERAND (arg0, 1),
- const_binop (PLUS_EXPR, arg2,
- integer_one_node, 0),
- OEP_ONLY_CONST))
- return pedantic_non_lvalue
- (fold (build2 (MIN_EXPR, type, arg1, arg2)));
- break;
-
- case LE_EXPR:
- /* If C1 is C2 - 1, this is min(A, C2). */
- if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
- OEP_ONLY_CONST)
- && operand_equal_p (TREE_OPERAND (arg0, 1),
- const_binop (MINUS_EXPR, arg2,
- integer_one_node, 0),
- OEP_ONLY_CONST))
- return pedantic_non_lvalue
- (fold (build2 (MIN_EXPR, type, arg1, arg2)));
- break;
-
- case GT_EXPR:
- /* If C1 is C2 - 1, this is max(A, C2). */
- if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
- OEP_ONLY_CONST)
- && operand_equal_p (TREE_OPERAND (arg0, 1),
- const_binop (MINUS_EXPR, arg2,
- integer_one_node, 0),
- OEP_ONLY_CONST))
- return pedantic_non_lvalue
- (fold (build2 (MAX_EXPR, type, arg1, arg2)));
- break;
-
- case GE_EXPR:
- /* If C1 is C2 + 1, this is max(A, C2). */
- if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
- OEP_ONLY_CONST)
- && operand_equal_p (TREE_OPERAND (arg0, 1),
- const_binop (PLUS_EXPR, arg2,
- integer_one_node, 0),
- OEP_ONLY_CONST))
- return pedantic_non_lvalue
- (fold (build2 (MAX_EXPR, type, arg1, arg2)));
- break;
- case NE_EXPR:
- break;
- default:
- abort ();
- }
}
/* If the second operand is simpler than the third, swap them
return pedantic_non_lvalue (fold_convert (type,
invert_truthvalue (arg0)));
- /* Look for expressions of the form A & 2 ? 2 : 0. The result of this
- operation is simply A & 2. */
+ /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
+ if (TREE_CODE (arg0) == LT_EXPR
+ && integer_zerop (TREE_OPERAND (arg0, 1))
+ && integer_zerop (TREE_OPERAND (t, 2))
+ && (tem = sign_bit_p (TREE_OPERAND (arg0, 0), arg1)))
+ return fold_convert (type, fold (build2 (BIT_AND_EXPR,
+ TREE_TYPE (tem), tem, arg1)));
+ /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
+ already handled above. */
+ if (TREE_CODE (arg0) == BIT_AND_EXPR
+ && integer_onep (TREE_OPERAND (arg0, 1))
+ && integer_zerop (TREE_OPERAND (t, 2))
+ && integer_pow2p (arg1))
+ {
+ tree tem = TREE_OPERAND (arg0, 0);
+ STRIP_NOPS (tem);
+ if (TREE_CODE (tem) == RSHIFT_EXPR
+ && (unsigned HOST_WIDE_INT) tree_log2 (arg1) ==
+ TREE_INT_CST_LOW (TREE_OPERAND (tem, 1)))
+ return fold (build2 (BIT_AND_EXPR, type,
+ TREE_OPERAND (tem, 0), arg1));
+ }
+
+ /* A & N ? N : 0 is simply A & N if N is a power of two. This
+ is probably obsolete because the first operand should be a
+ truth value (that's why we have the two cases above), but let's
+ leave it in until we can confirm this for all front-ends. */
if (integer_zerop (TREE_OPERAND (t, 2))
&& TREE_CODE (arg0) == NE_EXPR
&& integer_zerop (TREE_OPERAND (arg0, 1))
if (integer_zerop (TREE_OPERAND (t, 2))
&& truth_value_p (TREE_CODE (arg0))
&& truth_value_p (TREE_CODE (arg1)))
- return pedantic_non_lvalue (fold (build2 (TRUTH_ANDIF_EXPR, type,
- arg0, arg1)));
+ return fold (build2 (TRUTH_ANDIF_EXPR, type, arg0, arg1));
/* Convert A ? B : 1 into !A || B if A and B are truth values. */
if (integer_onep (TREE_OPERAND (t, 2))
/* Only perform transformation if ARG0 is easily inverted. */
tem = invert_truthvalue (arg0);
if (TREE_CODE (tem) != TRUTH_NOT_EXPR)
- return pedantic_non_lvalue (fold (build2 (TRUTH_ORIF_EXPR, type,
- tem, arg1)));
+ return fold (build2 (TRUTH_ORIF_EXPR, type, tem, arg1));
}
+ /* Convert A ? 0 : B into !A && B if A and B are truth values. */
+ if (integer_zerop (arg1)
+ && truth_value_p (TREE_CODE (arg0))
+ && truth_value_p (TREE_CODE (TREE_OPERAND (t, 2))))
+ {
+ /* Only perform transformation if ARG0 is easily inverted. */
+ tem = invert_truthvalue (arg0);
+ if (TREE_CODE (tem) != TRUTH_NOT_EXPR)
+ return fold (build2 (TRUTH_ANDIF_EXPR, type, tem,
+ TREE_OPERAND (t, 2)));
+ }
+
+ /* Convert A ? 1 : B into A || B if A and B are truth values. */
+ if (integer_onep (arg1)
+ && truth_value_p (TREE_CODE (arg0))
+ && truth_value_p (TREE_CODE (TREE_OPERAND (t, 2))))
+ return fold (build2 (TRUTH_ORIF_EXPR, type, arg0,
+ TREE_OPERAND (t, 2)));
+
return t;
case COMPOUND_EXPR:
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