On 7/29/2026 1:20 AM, Jin Ma wrote:
MI thunks generate RTL as if reload were complete and emit it directly
without running register allocation. Creating a pseudo while
materializing an invalid sibcall address therefore triggers the
gen_reg_rtx assertion.
Use STATIC_CHAIN_REGNUM for this post-reload thunk path. It is available
as a temporary in MI thunks and belongs to SIBCALL_REGS. Keep using a
pseudo for sibcalls expanded before register allocation.
PR target/126449
gcc/ChangeLog:
* config/riscv/riscv.cc (riscv_legitimize_call_address): Use
STATIC_CHAIN_REGNUM when a sibcall address is materialized in
post-reload thunk code.
gcc/testsuite/ChangeLog:
* g++.target/riscv/pr126449.C: New test.
Yea, for thunks we really need to use a physical register. Others bury
this in their output_mi_thunk routine, but the net is the same.
OK. Thanks for chasing this down.
jeff
