[llvm] AMDGPU/GlobalISel: Implement RegBankLegalizeRules for amdgcn_log, amdgcn_rcp, and amdgcn_sqrt (PR #195099)

[Petar Avramovic via llvm-commits]

petar-avramovic wrote:

## RegBankLegalize coverage check

| Opcode | Rule | Test file | Function | Status |
|--------|------|-----------|----------|--------|
| amdgcn_rcp | Div S16 | pseudo-scalar-transcendental.ll | v_rcp_f16_div | ✅ |
| amdgcn_rcp | Uni S16, hasPST | pseudo-scalar-transcendental.ll | v_s_rcp_f16 | ✅ |
| amdgcn_rcp | Uni S16, !hasPST | pseudo-scalar-transcendental.ll | v_s_rcp_f16 | ✅ |
| amdgcn_rcp | Div S32 | pseudo-scalar-transcendental.ll | v_rcp_f32_div | ✅ |
| amdgcn_rcp | Uni S32, hasPST | pseudo-scalar-transcendental.ll | v_s_rcp_f32 | ✅ |
| amdgcn_rcp | Uni S32, !hasPST | pseudo-scalar-transcendental.ll | v_s_rcp_f32 | ✅ |
| amdgcn_rcp | Div S64 | pseudo-scalar-transcendental.ll | v_rcp_f64_div | ✅ |
| amdgcn_rcp | Uni S64 | pseudo-scalar-transcendental.ll | v_s_rcp_f64 | ✅ |
| amdgcn_log | Div S16 | pseudo-scalar-transcendental.ll | v_amdgcn_log_f16_div | ✅ |
| amdgcn_log | Uni S16, hasPST | pseudo-scalar-transcendental.ll | v_s_amdgcn_log_f16 | ✅ |
| amdgcn_log | Uni S16, !hasPST | pseudo-scalar-transcendental.ll | v_s_amdgcn_log_f16 | ✅ |
| amdgcn_log | Div S32 | pseudo-scalar-transcendental.ll | v_amdgcn_log_f32_div | ✅ |
| amdgcn_log | Uni S32, hasPST | pseudo-scalar-transcendental.ll | v_s_log_f32 | ✅ |
| amdgcn_log | Uni S32, !hasPST | pseudo-scalar-transcendental.ll | v_s_log_f32 | ✅ |

All 14 rules (8 for `amdgcn_rcp`, 6 for `amdgcn_log`) are covered. No missing tests.

> *Automated check — not a human review. Generated by Claude (claude.ai).*

https://github.com/llvm/llvm-project/pull/195099