match: Simplify value-range guarded min/max expressions [PR125700] #214

sam-100 · 2026-08-10T06:22:31Z

sam-100 commented

2026-08-10 06:22:31 +00:00

The pattern:

    x == C ? y : min (x, y)

can be simplified to min (x, y) whenever C >= upper_bound (y),
because min (C, y) == y for all values y can take. Similarly:

    x == C ? y : max (x, y)

can be simplified to max (x, y) whenever C <= lower_bound (y).

Use ranger to query the value range of y and check the bound condition.

    PR tree-optimization/125700

gcc/ChangeLog:
PR tree-optimization/125700
* match.pd ((x == C) ? y : MIN/MAX (x, y)): New simplification.

gcc/testsuite/ChangeLog:

* gcc.dg/tree-ssa/pr125700.c: New test.
* gcc.dg/tree-ssa/pr125700-int-width.c: New test.
* gcc.dg/tree-ssa/pr125700-negative.c: New test.
* gcc.dg/tree-ssa/pr125700-range.c: New test.

Signed-off-by: Samarth Tandale samarth.tandale@oss.qualcomm.com

Testing:
Regression tested a cross compiler targeting AArch64 GNU/Linux on an
x86_64 GNU/Linux host, with execution tests run under QEMU; no
regressions found.

Changes since v1:

Extended the optimization beyond fixed type limits. It now handles constants
when Ranger proves their relationship with y's value range and conservatively
falls back when no useful range is available.
Added positive and negative test cases for Ranger-derived ranges.

CC: andrew.pinski@oss.qualcomm.com

The pattern: x == C ? y : min (x, y) can be simplified to min (x, y) whenever C >= upper_bound (y), because min (C, y) == y for all values y can take. Similarly: x == C ? y : max (x, y) can be simplified to max (x, y) whenever C <= lower_bound (y). Use ranger to query the value range of y and check the bound condition. PR tree-optimization/125700 gcc/ChangeLog: PR tree-optimization/125700 * match.pd ((x == C) ? y : MIN/MAX (x, y)): New simplification. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/pr125700.c: New test. * gcc.dg/tree-ssa/pr125700-int-width.c: New test. * gcc.dg/tree-ssa/pr125700-negative.c: New test. * gcc.dg/tree-ssa/pr125700-range.c: New test. Signed-off-by: Samarth Tandale <samarth.tandale@oss.qualcomm.com> Testing: Regression tested a cross compiler targeting AArch64 GNU/Linux on an x86_64 GNU/Linux host, with execution tests run under QEMU; no regressions found. Changes since v1: - Extended the optimization beyond fixed type limits. It now handles constants when Ranger proves their relationship with y's value range and conservatively falls back when no useful range is available. - Added positive and negative test cases for Ranger-derived ranges. CC: andrew.pinski@oss.qualcomm.com

sam-100 added 1 commit

2026-08-10 06:22:31 +00:00

match: Simplify type-bound guarded min/max expressions [PR125700 ]

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4d042112a6

For MIN_EXPR, if x is TYPE_MAX_VALUE, then min (x, y) is y.
So:
	x == TYPE_MAX_VALUE ? y : min (x, y)
can be simplified to:
	min (x, y)

Similarly for MAX_EXPR, if x is TYPE_MIN_VALUE, then max (x, y)
is y.
So:
	x == TYPE_MIN_VALUE ? y : max (x, y)
can be simplified to:
	max (x, y)

This adds a combined match.pd pattern for MIN_EXPR and MAX_EXPR.

	PR tree-optimization/125700

gcc/ChangeLog:

	* match.pd: Fold type-bound guarded min/max expressions.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr125700.c: New test.
	* gcc.dg/tree-ssa/pr125700-int-width.c: New test.
	* gcc.dg/tree-ssa/pr125700-negative.c: New test.

Signed-off-by: Samarth Tandale <samarth.tandale@oss.qualcomm.com>

forge-bot commented

2026-08-10 06:22:32 +00:00

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Hi @sam-100. This bot helps send your PR as a patch series to the mailing list. ## Next steps 1. Write a clear PR description. It will be used as the cover letter. 2. To CC extra people, add lines like this **at the end** of the PR description: `CC: Reviewer1 <revi.ewer@example.com>, Reviewer2 <an.other@example.com>`. 3. To preview the emails, comment with `/preview`. 4. When ready, request review in the Reviewers section. Or, if you just want to send the series, comment with `/submit`. 5. Use the cover-letter links below to follow replies. 6. For a new patch series, push your changes, update the PR description with a `Changes since vX` section, and comment with `/submit` again. See [Submitting Patches](https://gcc.gnu.org/contribute.html#patches) and [UsingForge](https://gcc.gnu.org/wiki/UsingForge). Consider joining the [gcc and gcc-patches mailing lists.](https://gcc.gnu.org/lists.html). For real time communication, check the [gcc irc channels](https://gcc.gnu.org/wiki/GCConIRC). Or join [`#overseers`](https://web.libera.chat/#overseers) on Libera Chat, particularly if this automation is not working (stay online to get replies, IRC does not save messages if people are not online).

pinskia requested changes

2026-08-10 06:35:25 +00:00

gcc/match.pd Outdated

					
				@ -12710,0 +12719,4 @@

				   (with {

				     tree bound = (minmax == MIN_EXPR)

						  ? TYPE_MAX_VALUE (type)

						  : TYPE_MIN_VALUE (type);

I think we should use the ranger here.
Similar to minmax_from_comparison.
It should be something like

          int_range_max r;
          get_range_query (cfun)->range_of_expr (r, @0);
          if (r.undefined_p ())
            r.set_varying (TREE_TYPE (@0));
          widest_int value;
          if (minmax == MIN_EXPR)
            value = widest_int::from (r.upper_bound (),
                                                     TYPE_SIGN (TREE_TYPE (@0)));
          else
            value = widest_int::from (r.lower_bound (),
                                                     TYPE_SIGN (TREE_TYPE (@0)));

Then the if would be:
if (max == wi::to_widdest (@0))

I think we should use the ranger here. Similar to minmax_from_comparison. It should be something like ``` int_range_max r; get_range_query (cfun)->range_of_expr (r, @0); if (r.undefined_p ()) r.set_varying (TREE_TYPE (@0)); widest_int value; if (minmax == MIN_EXPR) value = widest_int::from (r.upper_bound (), TYPE_SIGN (TREE_TYPE (@0))); else value = widest_int::from (r.lower_bound (), TYPE_SIGN (TREE_TYPE (@0))); ``` Then the if would be: if (max == wi::to_widdest (@0))

I tried using the ranger as suggested. However, get_range_query (cfun)->range_of_expr (r, @0) does not to consider the conditional context in which @0 is being queried, so it does not provide the path-specific range established by the surrounding condition.

I also tried gimple_match_range_of_expr (r, @0, @0). However, the helper uses gimple_match_ctx (@0), which provides the definition statement of @0 as the context. In this case, that statement is outside the if (x <= 100) block, so the conditional range is still not considered.

Could you please verify whether this is the intended use of the ranger, or advise how to query the range of @0 using the current conditional context?

I tried using the ranger as suggested. However, get_range_query (cfun)->range_of_expr (r, @0) does not to consider the conditional context in which @0 is being queried, so it does not provide the path-specific range established by the surrounding condition. I also tried gimple_match_range_of_expr (r, @0, @0). However, the helper uses gimple_match_ctx (@0), which provides the definition statement of @0 as the context. In this case, that statement is outside the if (x <= 100) block, so the conditional range is still not considered. Could you please verify whether this is the intended use of the ranger, or advise how to query the range of @0 using the current conditional context?

forge-bot commented

2026-08-10 06:35:58 +00:00

Version 1 of this pull request has been stored. It includes the following commits:

match: Simplify type-bound guarded min/max expressions [PR125700] - 4d042112a6

Version 1 of this pull request has been stored. It includes the following commits: - match: Simplify type-bound guarded min/max expressions [PR125700] - 4d042112a60614fdea9eface9d3b6c00fab7a260

sam-100 force-pushed pr125700 from 4d042112a6

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to 7e709962d4

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2026-09-19 07:42:54 +00:00

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sam-100 commented

2026-09-19 10:21:48 +00:00

/preview

forge-bot commented

2026-09-19 10:21:56 +00:00

Sent patch version 2 as a single email to @sam-100's email address.
Message ID is <bmm.hmfovtrc2o.gcc.gcc.sam-100.214.2.0@forge-stage.sourceware.org>.

Sent patch version 2 as a single email to @sam-100's email address. Message ID is `<bmm.hmfovtrc2o.gcc.gcc.sam-100.214.2.0@forge-stage.sourceware.org>`.

sam-100 commented

2026-09-19 10:29:08 +00:00

/submit

forge-bot commented

2026-09-19 10:29:47 +00:00

Version 2 of this pull request has been stored. It includes the following commits:

match: Simplify value-range guarded min/max expressions [PR125700] - 7e709962d4

Version 2 of this pull request has been stored. It includes the following commits: - match: Simplify value-range guarded min/max expressions [PR125700] - 7e709962d4f3c68b0f6f2522c743109a0d11aeea

forge-bot commented

2026-09-19 10:29:47 +00:00

Pull Request versions:

#	Base	Head
1	`19a304d368`	`4d042112a6`	(diff)
2	`7f405dfaa2`	`7e709962d4`	(diff)

In order to compare , clone this repository and run

PR=214
git fetch origin "refs/versioned_pull/${PR}/*:refs/versioned_pull/${PR}/*"
PRV1=1
PRV2=2
git range-diff "refs/versioned_pull/${PR}/${PRV1}/base..refs/versioned_pull/${PR}/${PRV1}/head"  "refs/versioned_pull/${PR}/${PRV2}/base..refs/versioned_pull/${PR}/${PRV2}/head"

Pull Request versions: | # | Base | Head | | | - | ---- | ---- | - | | 1 | 19a304d3680a1aeeb8ca412a6fe108a3f3b9d305 | 4d042112a60614fdea9eface9d3b6c00fab7a260 | [(diff)](https://forge.sourceware.org/gcc/gcc.git/compare/19a304d3680a1aeeb8ca412a6fe108a3f3b9d305...4d042112a60614fdea9eface9d3b6c00fab7a260) | | 2 | 7f405dfaa29e4c9d8c7b4e6ada13fa44ff053a0c | 7e709962d4f3c68b0f6f2522c743109a0d11aeea | [(diff)](https://forge.sourceware.org/gcc/gcc.git/compare/7f405dfaa29e4c9d8c7b4e6ada13fa44ff053a0c...7e709962d4f3c68b0f6f2522c743109a0d11aeea) | In order to compare , clone this repository and run ``` PR=214 git fetch origin "refs/versioned_pull/${PR}/*:refs/versioned_pull/${PR}/*" PRV1=1 PRV2=2 git range-diff "refs/versioned_pull/${PR}/${PRV1}/base..refs/versioned_pull/${PR}/${PRV1}/head" "refs/versioned_pull/${PR}/${PRV2}/base..refs/versioned_pull/${PR}/${PRV2}/head" ```

forge-bot commented

2026-09-19 10:30:21 +00:00

Sent patch version 2 as a single email to gcc-patches mailing list gcc-patches@gcc.gnu.org and cc'd andrew.pinski@oss.qualcomm.com.
Cover letter

Sent patch version 2 as a single email to gcc-patches mailing list <gcc-patches@gcc.gnu.org> and cc'd andrew.pinski@oss.qualcomm.com. [Cover letter](https://inbox.sourceware.org/gcc-patches/bmm.hmfp34cu8w.gcc.gcc.sam-100.214.2.0@forge-stage.sourceware.org)

sam-100 changed title from ~~match: Simplify type-bound guarded min/max expressions [PR125700]~~ to match: Simplify range-bound guarded min/max expressions [PR125700]

2026-09-19 17:32:39 +00:00

sam-100 changed title from ~~match: Simplify range-bound guarded min/max expressions [PR125700]~~ to match: Simplify value-range guarded min/max expressions [PR125700]

2026-09-19 17:37:32 +00:00

sam-100 closed this pull request

2026-09-21 05:05:44 +00:00

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