Fix EC field TrappedFP annotation.

[kisum9]

TrappedFP also only available for FEAT_AA32.

Originally posted by @thejpster in #60 (comment)

Fixed issue #62

[Copilot]

Pull request overview

This PR updates documentation comments for Exception Class (EC) values in the ESR (Exception Syndrome Register) definitions to correctly annotate feature dependencies. The primary change adds the (FEAT_AA32) annotation to the TrappedFP exception class, clarifying that trapping of floating-point/SIMD functionality is only available in AArch32 state.

Key Changes

• Added (FEAT_AA32) annotation to TrappedFP exception class comments in both ESR_EL1 and ESR_EL2 registers
• Added (FEAT_BTI) annotation to IllegalExecutionState exception class comment in ESR_EL2 register

Reviewed changes

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

File	Description
src/registers/esr_el1.rs	Updated TrappedFP documentation to indicate FEAT_AA32 dependency
src/registers/esr_el2.rs	Updated TrappedFP documentation to indicate FEAT_AA32 dependency and IllegalExecutionState to indicate FEAT_BTI dependency

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[Copilot]

The IllegalExecutionState exception (EC=0b001110) is not specific to FEAT_BTI. According to ARM architecture specifications, this exception class is used when an attempt is made to execute in an illegal execution state (e.g., attempting to execute AArch32 code when AArch32 is not supported at the current exception level). This is a general architectural exception that exists independently of FEAT_BTI.

While BranchTarget (EC=0b001101) is correctly annotated with FEAT_BTI, IllegalExecutionState should not have this annotation. Consider removing the (FEAT_BTI) annotation from this line.

Suggested change

	/// Illegal Execution state (FEAT_BTI)
	/// Illegal Execution state

[berkus]

@kisum9 I think copilot is right here, FEAT_BTI is not related to IllegalStateException, it's just unfortunate markup errors in the ARM ARM.

[berkus]

Please remove FEAT_BTI.

[thejpster]

So I think both of these only apply when FEAT_BTI is set. They've elided the second row in that column because it's the same as the one above.

[kisum9]

@berkus I agree with @thejpster. ESR_EL1 and ESR_EL2 both set FEAT_BTI for IllegalExecutionState，maybe add comment like “With FEAT_BTI implemented, this EC may also be used for BTI-related faults“

[berkus]

So I think both of these only apply when FEAT_BTI is set. They've elided the second row in that column because it's the same as the one above.

hmm I've looked in other places and it doesn't seem elided to me, e.g.

Are instruction aborts only supported when scalable matrix extension is enabled? I don't think so.

[berkus]

This document might look more usable.

[berkus]

In the ARM ARM markup they just literally missed to fill in the <td> when there is no text, leading to this weird look.

[kisum9]

Got it ；）