S and U tests at 100% coverage in Sail

[davidharrishmc]

Does not match Spike yet because of parameters
No self-checking trap handler yet available

[Copilot]

Pull request overview

This PR adds two new test generator files (S.py and U.py) for RISC-V supervisor-mode and user-mode privileged extension tests, modifies the machine-mode Sm.py to simplify the ecall/ebreak handling, extends csr.py to skip the MODE bit of satp during walking-ones tests, and updates S_coverage.svh to add mret to the supervisor-mode cp_sprivinst coverpoint and introduce cp_csr_ro coverage for supervisor-mode read-only CSR writes.

Changes:

• S.py and U.py added as new privileged extension test generators for S-mode and U-mode
• Sm.py simplified: removed check_reg allocation, signal writes, and register cleanup from _generate_priv_inst_tests; added test_{count}: labels for trap-handler use
• csr.py updated to skip MODE bits (bits 60-63 for RV64, bit 31 for RV32) when walking ones in satp; skip walking zeros for satp entirely
• S_coverage.svh updated: adds mret bin to privinstrs, removes the redundant cp_mret_s cross coverage, and adds cp_csr_ro cross coverage for supervisor-mode read-only CSR write attempts

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
generators/testgen/src/testgen/priv/extensions/U.py	New U-mode test generator for privileged instructions and CSR access/privilege tests
generators/testgen/src/testgen/priv/extensions/S.py	New S-mode test generator for ecall/ebreak/mret, sret, CSR access, and shadow register tests
generators/testgen/src/testgen/priv/extensions/Sm.py	Simplified ecall/ebreak tests to remove self-checking code pending trap handler support
generators/testgen/src/testgen/asm/csr.py	Added satp-specific logic to skip the MODE bit during walking-ones tests
coverpoints/priv/S_coverage.svh	Added mret to S-mode privinstrs, added cp_csr_ro coverpoint, removed cp_mret_s

[jordancarlin]

Still need to review S, but here are comments on the rest.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.