JIT: tighten IV range from "i != bound" assertions in rangecheck by AndyAyersMS · Pull Request #129303 · dotnet/runtime

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

AndyAyersMS · 2026-06-11T17:09:57Z

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects).

Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using X != bound / X == bound. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving len > 0 after a len != 0 check).

Contributes to #84697.

Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to dotnet#84697.

AndyAyersMS · 2026-06-11T17:11:00Z

@EgorBo this is the second part of what was in #129199... (first part was #129268).

dotnet-policy-service · 2026-06-11T17:11:18Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends CoreCLR JIT assertion generation and RangeCheck range-tightening to better exploit loop conditions of the form i != <checked-bound> (e.g., i != arr.Length) by creating/consuming checked-bound equality/inequality assertions to tighten IV ranges and enable more bounds-check elimination outside of loop cloning.

Changes:

Teach optCreateJTrueBoundsAssertion to generate CompareCheckedBound assertions for EQ/NE against checked bounds (while deferring checked-bound-vs-constant equalities to existing equality assertion paths).
Extend RangeCheck::MergeEdgeAssertionsWorker to tighten ranges using X != bound (when an existing limit is exactly bound) and X == bound.
Relax debug validation to allow O2K_VN_ADD_CNS assertions that are equality/inequality (not only ordered relops).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/jit/rangecheck.cpp	Tightens IV ranges based on checked-bound `==/!=` assertions when limits match the bound.
src/coreclr/jit/assertionprop.cpp	Generates checked-bound `==/!=` assertions for JTRUE relops and updates debug assertion validation accordingly.

EgorBo · 2026-06-12T10:34:00Z

+ // the bound. Tighten:
+ // [lo, bound] -> [lo, bound - 1]
+ // [bound, hi] -> [bound + 1, hi]
+ if (pRange->UpperLimit().IsBinOpArray() && (pRange->UpperLimit().vn == boundVN) &&


I suspect [bound, ..] assertions aren't useful generally, but it's fine to keep

EgorBo · 2026-06-12T10:38:32Z

+ // useful than a CompareCheckedBound form -- downstream consumers (folding bounds checks,
+ // proving "len > 0" after a "len != 0" test) only recognize the LCLVAR form. Skip the new
+ // assertion in that case and let the LCLVAR path produce it.
+ if (!(isEqualityRelop && vnStore->IsVNConstant(op2VN)))


This can be omitted if AssertionDsc::CreateCompareCheckedBound becomes smarter and switches automatically from O2K_VN_ADD_CNS to O2K_INT_CONST when the vn is a constant

EgorBo · 2026-06-12T10:39:39Z

Merged so I can do a small cleanup on top of it

…9303) Follow-on to "JIT: clone i != arr.Length loops to eliminate bounds checks". The cloning change handles NE-loop BCE for loops the cloning heuristic accepts. This change extends NE-loop BCE to cases that fall outside loop cloning (e.g. loops with side-effecting calls in the body that the cloning heuristic rejects). Extend optCreateJTrueBoundsAssertion to create CompareCheckedBound assertions for EQ/NE against a checked bound, and teach RangeCheck::MergeAssertion to tighten ranges using `X != bound` / `X == bound`. For equality assertions where the non-bound side is a constant, defer to the existing LCLVAR-based equality assertion path to preserve downstream consumers that rely on it (e.g. proving `len > 0` after a `len != 0` check). Contributes to #84697.

CopilotAI review requested due to automatic review settings June 11, 2026 17:09

Copilotstarted reviewing on behalf of AndyAyersMS June 11, 2026 17:10 View session

github-actionsBot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Jun 11, 2026

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[browser][coreCLR] Wasm.Console.Node.Sample - undefined symbol: SystemInteropJS_GetManagedStackTrace #129229
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EgorBo enabled auto-merge (squash) June 12, 2026 10:38

EgorBo merged commit 5beef0d into dotnet:mainJun 12, 2026
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[main] Source code updates from dotnet/runtime dotnet/dotnet#7196
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[Perf] Windows/x64: 18 Improvements on 6/12/2026 1:25:17 PM +00:00 dotnet/perf-autofiling-issues#74572
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