Re: [patch tree-optimization]: [2 of 3]: Boolify compares & more

[Richard Guenther <richard dot guenther at gmail dot com>]

On Tue, Jul 12, 2011 at 2:21 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
> 2011/7/12 Richard Guenther <richard.guenther@gmail.com>:
>> On Tue, Jul 12, 2011 at 11:48 AM, Kai Tietz <ktietz70@googlemail.com> wrote:
>>> 2011/7/12 Richard Guenther <richard.guenther@gmail.com>:
>>>> On Mon, Jul 11, 2011 at 5:37 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>>>>> 2011/7/8 Richard Guenther <richard.guenther@gmail.com>:
>>>>>> On Fri, Jul 8, 2011 at 1:32 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>>>>>>> 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. ?For 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-expression
>>>>>>>>> with truth-logic - but it has shown to short-cut some expensier folding. So
>>>>>>>>> I kept it within this patch.
>>>>>>>>
>>>>>>>> Please split it out. ?Also ...
>>>>>>>>
>>>>>>>>>
>>>>>>>>> The adjusted testcase gcc.dg/uninit-15.c indicates that due
>>>>>>>>> optimization we loose
>>>>>>>>> in this case variables declaration. ?But this might be to be expected.
>>>>>>>>>
>>>>>>>>> In vectorization we have a regression in gcc.dg/vect/vect-cond-3.c
>>>>>>>>> test-case. ?It's caused
>>>>>>>>> by always having boolean-type on conditions. ?So vectorizer sees
>>>>>>>>> different types, which
>>>>>>>>> aren't handled by vectorizer right now. ?Maybe 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 series.
>>>>>>>>>
>>>>>>>>> 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 ?Kai Tietz ?<ktietz@redhat.com>
>>>>>>>>>
>>>>>>>>> ? ? ? ?* fold-const.c (fold_unary_loc): Preserve
>>>>>>>>> ? ? ? ?non-boolean-typed casts.
>>>>>>>>> ? ? ? ?* gimplify.c (gimple_boolify): Handle boolification
>>>>>>>>> ? ? ? ?of comparisons.
>>>>>>>>> ? ? ? ?(gimplify_expr): Boolifiy non aggregate-typed
>>>>>>>>> ? ? ? ?comparisons.
>>>>>>>>> ? ? ? ?* tree-cfg.c (verify_gimple_comparison): Check result
>>>>>>>>> ? ? ? ?type of comparison expression.
>>>>>>>>> ? ? ? ?* tree-ssa.c (useless_type_conversion_p): Preserve incompatible
>>>>>>>>> ? ? ? ?casts from/to boolean,
>>>>>>>>> ? ? ? ?* tree-ssa-forwprop.c (combine_cond_expr_cond): Add simplification
>>>>>>>>> ? ? ? ?support for one-bit-precision typed X for cases X != 0 and X == 0.
>>>>>>>>> ? ? ? ?(forward_propagate_comparison): Adjust test of condition
>>>>>>>>> ? ? ? ?result.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ? ? ? ?* gcc.dg/tree-ssa/builtin-expect-5.c: Adjusted.
>>>>>>>>> ? ? ? ?* gcc.dg/tree-ssa/pr21031.c: Likewise.
>>>>>>>>> ? ? ? ?* gcc.dg/tree-ssa/pr30978.c: Likewise.
>>>>>>>>> ? ? ? ?* gcc.dg/tree-ssa/ssa-fre-6.c: Likewise.
>>>>>>>>> ? ? ? ?* gcc.dg/binop-xor1.c: Mark it as expected fail.
>>>>>>>>> ? ? ? ?* gcc.dg/binop-xor3.c: Likewise.
>>>>>>>>> ? ? ? ?* gcc.dg/uninit-15.c: Adjust reported message.
>>>>>>>>>
>>>>>>>>> Index: gcc-head/gcc/fold-const.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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
>>>>>>>>> ? ? ? ? ? ? non-integral type.
>>>>>>>>> ? ? ? ? ? ? Do not fold the result as that would not simplify further, also
>>>>>>>>> ? ? ? ? ? ? folding again results in recursions. ?*/
>>>>>>>>> - ? ? ? ? if (INTEGRAL_TYPE_P (type))
>>>>>>>>> + ? ? ? ? if (TREE_CODE (type) == BOOLEAN_TYPE)
>>>>>>>>> ? ? ? ? ? ?return build2_loc (loc, TREE_CODE (op0), type,
>>>>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_OPERAND (op0, 0),
>>>>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_OPERAND (op0, 1));
>>>>>>>>> - ? ? ? ? else
>>>>>>>>> + ? ? ? ? else if (!INTEGRAL_TYPE_P (type))
>>>>>>>>> ? ? ? ? ? ?return build3_loc (loc, COND_EXPR, type, op0,
>>>>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? fold_convert (type, boolean_true_node),
>>>>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? fold_convert (type, boolean_false_node));
>>>>>>>>> Index: gcc-head/gcc/gimplify.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- gcc-head.orig/gcc/gimplify.c
>>>>>>>>> +++ gcc-head/gcc/gimplify.c
>>>>>>>>> @@ -2842,18 +2842,23 @@ gimple_boolify (tree expr)
>>>>>>>>>
>>>>>>>>> ? ? case TRUTH_NOT_EXPR:
>>>>>>>>> ? ? ? TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0));
>>>>>>>>> - ? ? ?/* FALLTHRU */
>>>>>>>>>
>>>>>>>>> - ? ?case EQ_EXPR: case NE_EXPR:
>>>>>>>>> - ? ?case LE_EXPR: case GE_EXPR: case LT_EXPR: case GT_EXPR:
>>>>>>>>> ? ? ? /* These expressions always produce boolean results. ?*/
>>>>>>>>> - ? ? ?TREE_TYPE (expr) = boolean_type_node;
>>>>>>>>> + ? ? ?if (TREE_CODE (type) != BOOLEAN_TYPE)
>>>>>>>>> + ? ? ? TREE_TYPE (expr) = boolean_type_node;
>>>>>>>>> ? ? ? return expr;
>>>>>>>>>
>>>>>>>>> ? ? default:
>>>>>>>>> + ? ? ?if (COMPARISON_CLASS_P (expr))
>>>>>>>>> + ? ? ? {
>>>>>>>>> + ? ? ? ? /* There expressions always prduce boolean results. ?*/
>>>>>>>>> + ? ? ? ? if (TREE_CODE (type) != BOOLEAN_TYPE)
>>>>>>>>> + ? ? ? ? ? TREE_TYPE (expr) = boolean_type_node;
>>>>>>>>> + ? ? ? ? return expr;
>>>>>>>>> + ? ? ? }
>>>>>>>>> ? ? ? /* Other expressions that get here must have boolean values, but
>>>>>>>>> ? ? ? ? might need to be converted to the appropriate mode. ?*/
>>>>>>>>> - ? ? ?if (type == boolean_type_node)
>>>>>>>>> + ? ? ?if (TREE_CODE (type) == BOOLEAN_TYPE)
>>>>>>>>> ? ? ? ?return expr;
>>>>>>>>> ? ? ? return fold_convert_loc (loc, boolean_type_node, expr);
>>>>>>>>> ? ? }
>>>>>>>>> @@ -6763,7 +6768,7 @@ gimplify_expr (tree *expr_p, gimple_seq
>>>>>>>>> ? ? ? ? ? ?tree org_type = TREE_TYPE (*expr_p);
>>>>>>>>>
>>>>>>>>> ? ? ? ? ? ?*expr_p = gimple_boolify (*expr_p);
>>>>>>>>> - ? ? ? ? ? if (org_type != boolean_type_node)
>>>>>>>>> + ? ? ? ? ? if (!useless_type_conversion_p (org_type, TREE_TYPE (*expr_p)))
>>>>>>>>> ? ? ? ? ? ? ?{
>>>>>>>>> ? ? ? ? ? ? ? ?*expr_p = fold_convert (org_type, *expr_p);
>>>>>>>>
>>>>>>>> Use fold_convert_loc with saved_location
>>>>>>>
>>>>>>> Oh, good catch. Yes, I will adjust that.
>>>>>>>
>>>>>>>>> ? ? ? ? ? ? ? ?ret = GS_OK;
>>>>>>>>> @@ -7208,7 +7213,7 @@ gimplify_expr (tree *expr_p, gimple_seq
>>>>>>>>> ? ? ? ? ? ? ? fold_truth_not_expr) happily uses operand type and doesn't
>>>>>>>>> ? ? ? ? ? ? ? automatically uses boolean_type as result, we need to keep
>>>>>>>>> ? ? ? ? ? ? ? orignal type. ?*/
>>>>>>>>> - ? ? ? ? ? if (org_type != boolean_type_node)
>>>>>>>>> + ? ? ? ? ? if (!useless_type_conversion_p (org_type, TREE_TYPE (*expr_p)))
>>>>>>>>> ? ? ? ? ? ? ?{
>>>>>>>>> ? ? ? ? ? ? ? ?*expr_p = fold_convert (org_type, *expr_p);
>>>>>>>>
>>>>>>>> Likewise. ?Maybe this fixes the diagnostic regression.
>>>>>>>>
>>>>>>>>> ? ? ? ? ? ? ? ?ret = GS_OK;
>>>>>>>>> @@ -7288,7 +7293,19 @@ gimplify_expr (tree *expr_p, gimple_seq
>>>>>>>>> ? ? ? ? ? ? ? ? ?tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 1));
>>>>>>>>>
>>>>>>>>> ? ? ? ? ? ? ? ? ?if (!AGGREGATE_TYPE_P (type))
>>>>>>>>> - ? ? ? ? ? ? ? ? ? goto expr_2;
>>>>>>>>> + ? ? ? ? ? ? ? ? ? {
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? tree org_type = TREE_TYPE (*expr_p);
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? *expr_p = gimple_boolify (*expr_p);
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? if (!useless_type_conversion_p (org_type,
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_TYPE (*expr_p)))
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? {
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? *expr_p = fold_convert_loc (saved_location,
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? org_type, *expr_p);
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? ret = GS_OK;
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? }
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? else
>>>>>>>>> + ? ? ? ? ? ? ? ? ? ? ? goto expr_2;
>>>>>>>>> + ? ? ? ? ? ? ? ? ? }
>>>>>>>>> ? ? ? ? ? ? ? ? ?else if (TYPE_MODE (type) != BLKmode)
>>>>>>>>> ? ? ? ? ? ? ? ? ? ?ret = gimplify_scalar_mode_aggregate_compare (expr_p);
>>>>>>>>> ? ? ? ? ? ? ? ? ?else
>>>>>>>>> Index: gcc-head/gcc/tree-cfg.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- gcc-head.orig/gcc/tree-cfg.c
>>>>>>>>> +++ gcc-head/gcc/tree-cfg.c
>>>>>>>>> @@ -3203,7 +3203,9 @@ verify_gimple_comparison (tree type, tre
>>>>>>>>> ? ? ? ?&& (!POINTER_TYPE_P (op0_type)
>>>>>>>>> ? ? ? ? ? || !POINTER_TYPE_P (op1_type)
>>>>>>>>> ? ? ? ? ? || TYPE_MODE (op0_type) != TYPE_MODE (op1_type)))
>>>>>>>>> - ? ? ?|| !INTEGRAL_TYPE_P (type))
>>>>>>>>> + ? ? ?|| !INTEGRAL_TYPE_P (type)
>>>>>>>>> + ? ? ?|| (TREE_CODE (type) != BOOLEAN_TYPE
>>>>>>>>> + ? ? ? ? && TYPE_PRECISION (type) != 1))
>>>>>>>>> ? ? {
>>>>>>>>> ? ? ? error ("type mismatch in comparison expression");
>>>>>>>>> ? ? ? debug_generic_expr (type);
>>>>>>>>> Index: gcc-head/gcc/tree-ssa.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- gcc-head.orig/gcc/tree-ssa.c
>>>>>>>>> +++ gcc-head/gcc/tree-ssa.c
>>>>>>>>> @@ -1306,10 +1306,10 @@ useless_type_conversion_p (tree outer_ty
>>>>>>>>> ? ? ? ? ?|| TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
>>>>>>>>> ? ? ? ?return false;
>>>>>>>>>
>>>>>>>>> - ? ? ?/* Preserve conversions to BOOLEAN_TYPE if it is not of precision
>>>>>>>>> - ? ? ? ? one. ?*/
>>>>>>>>> - ? ? ?if (TREE_CODE (inner_type) != BOOLEAN_TYPE
>>>>>>>>> - ? ? ? ? && TREE_CODE (outer_type) == BOOLEAN_TYPE
>>>>>>>>> + ? ? ?/* Preserve conversions to/from BOOLEAN_TYPE if types are not
>>>>>>>>> + ? ? ? ?of precision one. ?*/
>>>>>>>>> + ? ? ?if (((TREE_CODE (inner_type) == BOOLEAN_TYPE)
>>>>>>>>> + ? ? ? ? ?!= (TREE_CODE (outer_type) == BOOLEAN_TYPE))
>>>>>>>>> ? ? ? ? ?&& TYPE_PRECISION (outer_type) != 1)
>>>>>>>>> ? ? ? ?return false;
>>>>>>>>>
>>>>>>>>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/builtin-expect-5.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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)
>>>>>>>>>
>>>>>>>>> ?/* { dg-final { scan-tree-dump-times { if } 2 "forwprop1"} } */
>>>>>>>>> ?/* { 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? ?Why that?
>>>>>>>>
>>>>>>>>> ?/* { dg-final { cleanup-tree-dump "forwprop?" } } */
>>>>>>>>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr21031.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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)
>>>>>>>>> ? ? return 0;
>>>>>>>>> ?}
>>>>>>>>>
>>>>>>>>> -/* { dg-final { scan-tree-dump-times "Replaced" 2 "forwprop1"} } */
>>>>>>>>> +/* { dg-final { scan-tree-dump-times "Replaced" 1 "forwprop1"} } */
>>>>>>>>> ?/* { dg-final { cleanup-tree-dump "forwprop1" } } */
>>>>>>>>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/pr30978.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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)
>>>>>>>>> ? return e;
>>>>>>>>> ?}
>>>>>>>>>
>>>>>>>>> -/* { dg-final { scan-tree-dump "e_. = a_..D. > 0;" "optimized" } } */
>>>>>>>>> +/* { dg-final { scan-tree-dump " = a_..D. > 0;" "optimized" } } */
>>>>>>>>> ?/* { dg-final { cleanup-tree-dump "optimized" } } */
>>>>>>>>> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-6.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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 @@
>>>>>>>>> ?/* { dg-options "-O -fdump-tree-fre1-details" } */
>>>>>>>>>
>>>>>>>>> ?int i; int foo(void) { i = 2; int j = i * 2; int k = i + 2; return j == k; }
>>>>>>>>> -/* { dg-final { scan-tree-dump-times "Replaced " 5 "fre1" } } */
>>>>>>>>> +/* { dg-final { scan-tree-dump-times "Replaced " 6 "fre1" } } */
>>>>>>>>> ?/* { dg-final { cleanup-tree-dump "fre1" } } */
>>>>>>>>> Index: gcc-head/gcc/tree-ssa-forwprop.c
>>>>>>>>> ===================================================================
>>>>>>>>> --- 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,
>>>>>>>>> ? gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);
>>>>>>>>>
>>>>>>>>> ? t = fold_binary_loc (loc, code, type, op0, op1);
>>>>>>>>> +
>>>>>>>>> + ?if (!t && INTEGRAL_TYPE_P (TREE_TYPE (op1))
>>>>>>>>> + ? ? ?&& TYPE_PRECISION (TREE_TYPE (op1)) == 1
>>>>>>>>> + ? ? ?&& (code == EQ_EXPR || code == NE_EXPR))
>>>>>>>>> + ? ?{
>>>>>>>>> + ? ? ?if (TREE_CODE (op1) == INTEGER_CST)
>>>>>>>>> + ? ? ? ?{
>>>>>>>>> + ? ? ? ? if (integer_onep (op1))
>>>>>>>>> + ? ? ? ? ? {
>>>>>>>>> + ? ? ? ? ? ? op1 = fold_convert_loc (loc, TREE_TYPE (op1), integer_zero_node);
>>>>>>>>> + ? ? ? ? ? ? code = (code == NE_EXPR ? EQ_EXPR : NE_EXPR);
>>>>>>>>
>>>>>>>> So you change truthvalue !=/== 1 to truthvalue ==/!= 0 and then
>>>>>>>> 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 !=/== 1 to !=/== 0 limits the amount
>>>>>>> of cases to handle. As for truthvalued X the we have then just to
>>>>>>> handle two cases. X != 0 -> X, and X == 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).
>>>>>>
>>>>>> We should have a canonical form for those compares and change
>>>>>> them accordingly, best in fold_stmt.
>>>>>>
>>>>>> Richard.
>>>>>
>>>>> Hmm, I tried to add this code-pattern to fold_stmt, but for this kind
>>>>> of branch it seems not to be invoked at all. At least not now without
>>>>> boolification of compares. ?One nit I found for GIMPLE_BINARY, as here
>>>>> just patterns getting replaced, which have fewer number of ops then
>>>>> original statement. This check looks a bit bogus.
>>>>> For getting this normalization right now in a consistant way,
>>>>> fold-const might be right now the better place to handle this.
>>>>
>>>> It gets invoked (well, should get invoked) when anyone changes the
>>>> statement. ?If it is present in that form from the beginning then we
>>>> lack canonicalization in fold and/or gimplification.
>>>>
>>>> I suppose you have a testcase?
>>>>
>>>> Richard.
>>>>
>>>>> Regards,
>>>>> Kai
>>>>>
>>>
>>> Yes, testcase looks like this:
>>>
>>> int foo (_Bool a, _Bool b)
>>> {
>>> ?return a != ((b | !b));
>>> }
>>>
>>> while reduces to
>>> ...
>>> return a != 1; ?right now, and not a == 0 (as a is boolean)
>>
>> fold_stmt should be called when copyprop produces a != 1
>> via substitute_and_fold:
>>
>> ? ? ? ? ?/* Replace real uses in the statement. ?*/
>> ? ? ? ? ?if (get_value_fn)
>> ? ? ? ? ? ?did_replace |= replace_uses_in (stmt, get_value_fn);
>>
>> ? ? ? ? ?/* If we made a replacement, fold the statement. ?*/
>> ? ? ? ? ?if (did_replace)
>> ? ? ? ? ? ?fold_stmt (&oldi);
>
> Well, I added this transformation for test in fold-const s
> fold_comparison function and still it doesn't get converted.
> I assume this caused by the fact that we do this optimization in
> forwprop on argument's of the comparison, so no try to fold statement
> happens here at this place.

The non-canonical comparison appears after copyprop for me.

Richard.

> Kai
>