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Date: Fri, 08 Jul 2011 11:35:00 -0000
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Subject: Re: [patch tree-optimization]: [2 of 3]: Boolify compares & more
From: Kai Tietz <ktietz70@googlemail.com>
To: Richard Guenther <richard.guenther@gmail.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
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2011/7/8 Richard Guenther <richard.guenther@gmail.com>:
> On Thu, Jul 7, 2011 at 6:07 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>> Hello,
>>
>> This patch - second of series - adds boolification of comparisions in
>> gimplifier. =A0For this
>> casts from/to boolean are marked as not-useless. And in fold_unary_loc
>> casts to non-boolean integral types are preserved.
>> The hunk in tree-ssa-forwprop.c in combine_cond-expr_cond is not strictly
>> necessary - as long as fold-const handles 1-bit precision bitwise-expres=
sion
>> with truth-logic - but it has shown to short-cut some expensier folding.=
 So
>> I kept it within this patch.
>
> Please split it out. =A0Also ...
>
>>
>> The adjusted testcase gcc.dg/uninit-15.c indicates that due
>> optimization we loose
>> in this case variables declaration. =A0But this might be to be expected.
>>
>> In vectorization we have a regression in gcc.dg/vect/vect-cond-3.c
>> test-case. =A0It's caused
>> by always having boolean-type on conditions. =A0So vectorizer sees
>> different types, which
>> aren't handled by vectorizer right now. =A0Maybe this issue could be
>> special-cased for
>> boolean-types in tree-vect-loop, by making operand for used condition
>> equal to vector-type.
>> But this is a subject for a different patch and not addressed by this se=
ries.
>>
>> There is a regressions in tree-ssa/vrp47.c, and the fix is addressed
>> by the 3rd patch of this
>> series.
>>
>> Bootstrapped and regression tested for all standard-languages (plus
>> Ada and Obj-C++) on host x86_64-pc-linux-gnu.
>>
>> Ok for apply?
>>
>> Regards,
>> Kai
>>
>>
>> ChangeLog
>>
>> 2011-07-07 =A0Kai Tietz =A0<ktietz@redhat.com>
>>
>> =A0 =A0 =A0 =A0* fold-const.c (fold_unary_loc): Preserve
>> =A0 =A0 =A0 =A0non-boolean-typed casts.
>> =A0 =A0 =A0 =A0* gimplify.c (gimple_boolify): Handle boolification
>> =A0 =A0 =A0 =A0of comparisons.
>> =A0 =A0 =A0 =A0(gimplify_expr): Boolifiy non aggregate-typed
>> =A0 =A0 =A0 =A0comparisons.
>> =A0 =A0 =A0 =A0* tree-cfg.c (verify_gimple_comparison): Check result
>> =A0 =A0 =A0 =A0type of comparison expression.
>> =A0 =A0 =A0 =A0* tree-ssa.c (useless_type_conversion_p): Preserve incomp=
atible
>> =A0 =A0 =A0 =A0casts from/to boolean,
>> =A0 =A0 =A0 =A0* tree-ssa-forwprop.c (combine_cond_expr_cond): Add simpl=
ification
>> =A0 =A0 =A0 =A0support for one-bit-precision typed X for cases X !=3D 0 =
and X =3D=3D 0.
>> =A0 =A0 =A0 =A0(forward_propagate_comparison): Adjust test of condition
>> =A0 =A0 =A0 =A0result.
>>
>>
>> =A0 =A0 =A0 =A0* gcc.dg/tree-ssa/builtin-expect-5.c: Adjusted.
>> =A0 =A0 =A0 =A0* gcc.dg/tree-ssa/pr21031.c: Likewise.
>> =A0 =A0 =A0 =A0* gcc.dg/tree-ssa/pr30978.c: Likewise.
>> =A0 =A0 =A0 =A0* gcc.dg/tree-ssa/ssa-fre-6.c: Likewise.
>> =A0 =A0 =A0 =A0* gcc.dg/binop-xor1.c: Mark it as expected fail.
>> =A0 =A0 =A0 =A0* gcc.dg/binop-xor3.c: Likewise.
>> =A0 =A0 =A0 =A0* gcc.dg/uninit-15.c: Adjust reported message.
>>
>> Index: gcc-head/gcc/fold-const.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/fold-const.c
>> +++ gcc-head/gcc/fold-const.c
>> @@ -7665,11 +7665,11 @@ fold_unary_loc (location_t loc, enum tre
>> =A0 =A0 =A0 =A0 =A0 =A0 non-integral type.
>> =A0 =A0 =A0 =A0 =A0 =A0 Do not fold the result as that would not simplif=
y further, also
>> =A0 =A0 =A0 =A0 =A0 =A0 folding again results in recursions. =A0*/
>> - =A0 =A0 =A0 =A0 if (INTEGRAL_TYPE_P (type))
>> + =A0 =A0 =A0 =A0 if (TREE_CODE (type) =3D=3D BOOLEAN_TYPE)
>> =A0 =A0 =A0 =A0 =A0 =A0return build2_loc (loc, TREE_CODE (op0), type,
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 TREE_OPERAND=
 (op0, 0),
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 TREE_OPERAND=
 (op0, 1));
>> - =A0 =A0 =A0 =A0 else
>> + =A0 =A0 =A0 =A0 else if (!INTEGRAL_TYPE_P (type))
>> =A0 =A0 =A0 =A0 =A0 =A0return build3_loc (loc, COND_EXPR, type, op0,
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 fold_convert=
 (type, boolean_true_node),
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 fold_convert=
 (type, boolean_false_node));
>> Index: gcc-head/gcc/gimplify.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/gimplify.c
>> +++ gcc-head/gcc/gimplify.c
>> @@ -2842,18 +2842,23 @@ gimple_boolify (tree expr)
>>
>> =A0 =A0 case TRUTH_NOT_EXPR:
>> =A0 =A0 =A0 TREE_OPERAND (expr, 0) =3D gimple_boolify (TREE_OPERAND (exp=
r, 0));
>> - =A0 =A0 =A0/* FALLTHRU */
>>
>> - =A0 =A0case EQ_EXPR: case NE_EXPR:
>> - =A0 =A0case LE_EXPR: case GE_EXPR: case LT_EXPR: case GT_EXPR:
>> =A0 =A0 =A0 /* These expressions always produce boolean results. =A0*/
>> - =A0 =A0 =A0TREE_TYPE (expr) =3D boolean_type_node;
>> + =A0 =A0 =A0if (TREE_CODE (type) !=3D BOOLEAN_TYPE)
>> + =A0 =A0 =A0 TREE_TYPE (expr) =3D boolean_type_node;
>> =A0 =A0 =A0 return expr;
>>
>> =A0 =A0 default:
>> + =A0 =A0 =A0if (COMPARISON_CLASS_P (expr))
>> + =A0 =A0 =A0 {
>> + =A0 =A0 =A0 =A0 /* There expressions always prduce boolean results. =
=A0*/
>> + =A0 =A0 =A0 =A0 if (TREE_CODE (type) !=3D BOOLEAN_TYPE)
>> + =A0 =A0 =A0 =A0 =A0 TREE_TYPE (expr) =3D boolean_type_node;
>> + =A0 =A0 =A0 =A0 return expr;
>> + =A0 =A0 =A0 }
>> =A0 =A0 =A0 /* Other expressions that get here must have boolean values,=
 but
>> =A0 =A0 =A0 =A0 might need to be converted to the appropriate mode. =A0*/
>> - =A0 =A0 =A0if (type =3D=3D boolean_type_node)
>> + =A0 =A0 =A0if (TREE_CODE (type) =3D=3D BOOLEAN_TYPE)
>> =A0 =A0 =A0 =A0return expr;
>> =A0 =A0 =A0 return fold_convert_loc (loc, boolean_type_node, expr);
>> =A0 =A0 }
>> @@ -6763,7 +6768,7 @@ gimplify_expr (tree *expr_p, gimple_seq
>> =A0 =A0 =A0 =A0 =A0 =A0tree org_type =3D TREE_TYPE (*expr_p);
>>
>> =A0 =A0 =A0 =A0 =A0 =A0*expr_p =3D gimple_boolify (*expr_p);
>> - =A0 =A0 =A0 =A0 =A0 if (org_type !=3D boolean_type_node)
>> + =A0 =A0 =A0 =A0 =A0 if (!useless_type_conversion_p (org_type, TREE_TYP=
E (*expr_p)))
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0{
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*expr_p =3D fold_convert (org_type, *expr=
_p);
>
> Use fold_convert_loc with saved_location

Oh, good catch. Yes, I will adjust that.

>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D GS_OK;
>> @@ -7208,7 +7213,7 @@ gimplify_expr (tree *expr_p, gimple_seq
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 fold_truth_not_expr) happily uses operand ty=
pe and doesn't
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 automatically uses boolean_type as result, w=
e need to keep
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 orignal type. =A0*/
>> - =A0 =A0 =A0 =A0 =A0 if (org_type !=3D boolean_type_node)
>> + =A0 =A0 =A0 =A0 =A0 if (!useless_type_conversion_p (org_type, TREE_TYP=
E (*expr_p)))
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0{
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*expr_p =3D fold_convert (org_type, *expr=
_p);
>
> Likewise. =A0Maybe this fixes the diagnostic regression.
>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D GS_OK;
>> @@ -7288,7 +7293,19 @@ gimplify_expr (tree *expr_p, gimple_seq
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0tree type =3D TREE_TYPE (TREE_OPERAND=
 (*expr_p, 1));
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!AGGREGATE_TYPE_P (type))
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto expr_2;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 tree org_type =3D TREE_TYPE (*=
expr_p);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 *expr_p =3D gimple_boolify (*e=
xpr_p);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!useless_type_conversion_p=
 (org_type,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 TREE_TYPE (*expr_p)))
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 *expr_p =3D fold_conve=
rt_loc (saved_location,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 org_type, *expr_p);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ret =3D GS_OK;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto expr_2;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0else if (TYPE_MODE (type) !=3D BLKmod=
e)
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D gimplify_scalar_mode_aggr=
egate_compare (expr_p);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0else
>> Index: gcc-head/gcc/tree-cfg.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/tree-cfg.c
>> +++ gcc-head/gcc/tree-cfg.c
>> @@ -3203,7 +3203,9 @@ verify_gimple_comparison (tree type, tre
>> =A0 =A0 =A0 =A0&& (!POINTER_TYPE_P (op0_type)
>> =A0 =A0 =A0 =A0 =A0 || !POINTER_TYPE_P (op1_type)
>> =A0 =A0 =A0 =A0 =A0 || TYPE_MODE (op0_type) !=3D TYPE_MODE (op1_type)))
>> - =A0 =A0 =A0|| !INTEGRAL_TYPE_P (type))
>> + =A0 =A0 =A0|| !INTEGRAL_TYPE_P (type)
>> + =A0 =A0 =A0|| (TREE_CODE (type) !=3D BOOLEAN_TYPE
>> + =A0 =A0 =A0 =A0 && TYPE_PRECISION (type) !=3D 1))
>> =A0 =A0 {
>> =A0 =A0 =A0 error ("type mismatch in comparison expression");
>> =A0 =A0 =A0 debug_generic_expr (type);
>> Index: gcc-head/gcc/tree-ssa.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/tree-ssa.c
>> +++ gcc-head/gcc/tree-ssa.c
>> @@ -1306,10 +1306,10 @@ useless_type_conversion_p (tree outer_ty
>> =A0 =A0 =A0 =A0 =A0|| TYPE_PRECISION (inner_type) !=3D TYPE_PRECISION (o=
uter_type))
>> =A0 =A0 =A0 =A0return false;
>>
>> - =A0 =A0 =A0/* Preserve conversions to BOOLEAN_TYPE if it is not of pre=
cision
>> - =A0 =A0 =A0 =A0 one. =A0*/
>> - =A0 =A0 =A0if (TREE_CODE (inner_type) !=3D BOOLEAN_TYPE
>> - =A0 =A0 =A0 =A0 && TREE_CODE (outer_type) =3D=3D BOOLEAN_TYPE
>> + =A0 =A0 =A0/* Preserve conversions to/from BOOLEAN_TYPE if types are n=
ot
>> + =A0 =A0 =A0 =A0of precision one. =A0*/
>> + =A0 =A0 =A0if (((TREE_CODE (inner_type) =3D=3D BOOLEAN_TYPE)
>> + =A0 =A0 =A0 =A0 =A0!=3D (TREE_CODE (outer_type) =3D=3D BOOLEAN_TYPE))
>> =A0 =A0 =A0 =A0 =A0&& TYPE_PRECISION (outer_type) !=3D 1)
>> =A0 =A0 =A0 =A0return false;
>>
>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/builtin-expect-5.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/testsuite/gcc.dg/tree-ssa/builtin-expect-5.c
>> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/builtin-expect-5.c
>> @@ -11,5 +11,5 @@ f (int i, float j)
>>
>> =A0/* { dg-final { scan-tree-dump-times { if } 2 "forwprop1"} } */
>> =A0/* { dg-final { scan-tree-dump {builtin_expect[^\n]*, 0\);\n[^\n]*if}
>> "forwprop1"} } */
>> -/* { dg-final { scan-tree-dump {builtin_expect[^\n]*, 1\);\n[^\n]*if}
>> "forwprop1"} } */
>> +/* { dg-final { scan-tree-dump-not {builtin_expect[^\n]*,
>> 1\);\n[^\n]*if} "forwprop1"} } */
>
> Hm? =A0Why that?
>
>> =A0/* { dg-final { cleanup-tree-dump "forwprop?" } } */
>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr21031.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/testsuite/gcc.dg/tree-ssa/pr21031.c
>> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr21031.c
>> @@ -16,5 +16,5 @@ foo (int a)
>> =A0 =A0 return 0;
>> =A0}
>>
>> -/* { dg-final { scan-tree-dump-times "Replaced" 2 "forwprop1"} } */
>> +/* { dg-final { scan-tree-dump-times "Replaced" 1 "forwprop1"} } */
>> =A0/* { dg-final { cleanup-tree-dump "forwprop1" } } */
>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr30978.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/testsuite/gcc.dg/tree-ssa/pr30978.c
>> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr30978.c
>> @@ -10,5 +10,5 @@ int foo(int a)
>> =A0 return e;
>> =A0}
>>
>> -/* { dg-final { scan-tree-dump "e_. =3D a_..D. > 0;" "optimized" } } */
>> +/* { dg-final { scan-tree-dump " =3D a_..D. > 0;" "optimized" } } */
>> =A0/* { dg-final { cleanup-tree-dump "optimized" } } */
>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-6.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-6.c
>> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-6.c
>> @@ -2,5 +2,5 @@
>> =A0/* { dg-options "-O -fdump-tree-fre1-details" } */
>>
>> =A0int i; int foo(void) { i =3D 2; int j =3D i * 2; int k =3D i + 2; ret=
urn j =3D=3D k; }
>> -/* { dg-final { scan-tree-dump-times "Replaced " 5 "fre1" } } */
>> +/* { dg-final { scan-tree-dump-times "Replaced " 6 "fre1" } } */
>> =A0/* { dg-final { cleanup-tree-dump "fre1" } } */
>> Index: gcc-head/gcc/tree-ssa-forwprop.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- gcc-head.orig/gcc/tree-ssa-forwprop.c
>> +++ gcc-head/gcc/tree-ssa-forwprop.c
>> @@ -367,9 +367,61 @@ combine_cond_expr_cond (location_t loc,
>> =A0 gcc_assert (TREE_CODE_CLASS (code) =3D=3D tcc_comparison);
>>
>> =A0 t =3D fold_binary_loc (loc, code, type, op0, op1);
>> +
>> + =A0if (!t && INTEGRAL_TYPE_P (TREE_TYPE (op1))
>> + =A0 =A0 =A0&& TYPE_PRECISION (TREE_TYPE (op1)) =3D=3D 1
>> + =A0 =A0 =A0&& (code =3D=3D EQ_EXPR || code =3D=3D NE_EXPR))
>> + =A0 =A0{
>> + =A0 =A0 =A0if (TREE_CODE (op1) =3D=3D INTEGER_CST)
>> + =A0 =A0 =A0 =A0{
>> + =A0 =A0 =A0 =A0 if (integer_onep (op1))
>> + =A0 =A0 =A0 =A0 =A0 {
>> + =A0 =A0 =A0 =A0 =A0 =A0 op1 =3D fold_convert_loc (loc, TREE_TYPE (op1)=
, integer_zero_node);
>> + =A0 =A0 =A0 =A0 =A0 =A0 code =3D (code =3D=3D NE_EXPR ? EQ_EXPR : NE_E=
XPR);
>
> So you change truthvalue !=3D/=3D=3D 1 to truthvalue =3D=3D/!=3D 0 and th=
en
> recurse ... that doesn't make sense to me and is super-ugly.
> What's the testcase that made you add all this code?

Well, the convert from truthvalue !=3D/=3D=3D 1 to !=3D/=3D=3D 0 limits the=
 amount
of cases to handle. As for truthvalued X the we have then just to
handle two cases. X !=3D 0 -> X, and X =3D=3D 0 -> (X ^ 1).
The recursion is someting I saw as existing pattern (for the same
thing) in truth-op folding in fold-const.

Actual I can remove this optimization here, as it should be convered
by VRP already (when VRP handles 1-bit precision bitwise ops proper).