[MercylinPreethi]

Summary

Collapse runs of adjacent LITERAL opcodes into one _sre dispatch.

In SRE(match), SRE_OP_LITERAL and SRE_OP_LITERAL_IGNORE each matched one character and then went back to the computed-goto dispatch. This change loops while the next opcode is the same literal opcode, so a run of N literal characters costs one dispatch instead of N.

Matching behavior is unchanged. The loop reads the next opcode right after each literal, which the old code did not do. That read stays in bounds because every compiled SRE pattern ends with SUCCESS or FAILURE.

Files: Modules/_sre/sre_lib.h

Measured

Text Processing workload, gain in % (positive means faster).

Vendor	CPU	OS	Compiler	Single thread	All threads
AMD	Ryzen 7 9700X (8 cores, 16 threads)	Windows	clang-cl 22.1	+2.1	+2.2
Intel	Core Ultra 9 285K (24 cores)	Windows	clang-cl 22.1	-1.2	-1.7
Apple	Mac Air	macOS	clang	+5.8	+4.3

Test plan

• Accuracy: same 3,914 tokens as upstream (identical digest).
• Unit test: Text Processing unit test passes on 3.13.1 and latest release, with and without the patch.
• Timing: single core and multi core on all three machines (table above).
• Regex tests: test_re passes on 3.13.1 and latest with the patch.

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[picnixz]

This requires an issue before as well as a justification of the change. The benchmarks aren't clear on what we actually gain.