feat: i64 register pairs, globals/select, WAST pipeline + spec-testsuite

[avrabe]

Summary

i64 Register Pair Support (all 38 operations)

• Arithmetic: ADDS/ADC (add), SUBS/SBC (sub), UMULL+MLA (mul)
• Bitwise: AND/ORR/EOR on both halves
• Comparisons: ORR+CMP (eqz), CMP-hi-then-lo (relational, signed+unsigned)
• Shifts: funnel shift sequences (shl, shr_u, shr_s, rotl, rotr)
• Division/Remainder: binary long division pseudo-ops (div_s, div_u, rem_s, rem_u)
• Conversions: I64ExtendI32S (ASR docs: Archive obsolete documentation #31), I64ExtendI32U (MOV #0), I32WrapI64 (take low)
• Memory: I64Load/Store (two consecutive LDR/STR at offset+0 and offset+4)
• Constants: I64Const (MOVW+MOVT for each half)
• 47 new tests (29 instruction selector + 18 encoder)

GlobalGet/GlobalSet

• R9 as globals base register, LDR/STR with 4-byte stride
• Both stack and non-stack instruction selection modes
• 10 new tests

Select Instruction

• CMP + MOV + SelectMove (IT EQ; MOV in Thumb-2) pattern
• 3 new tests

WAST Test Pipeline

• wast_multi_func_test Bazel macro replaces 2,480 lines of hand-crafted targets with 25 declarative calls
• All 22 .wast files wired into renode_test pipeline
• Compiles with --all-exports, tests all functions per module

Spec Test Suite

• Added WebAssembly/testsuite as git submodule (257 .wast files)
• ~20 files runnable today (i32 + control flow + locals), ~5 more with FPU

Rivet Artifacts

• SWVER-006: GlobalGet/GlobalSet verification
• SWVER-007: Select instruction verification

762 tests total (up from 687)

Test plan

• cargo test --workspace — 762 tests, 0 failures
• cargo clippy --workspace --all-targets -- -D warnings — clean
• cargo fmt --check — clean

🤖 Generated with Claude Code