https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94740
--- Comment #3 from Peter Bergner <bergner at gcc dot gnu.org> ---
Here's a simpler test case that fails the same way:
int array[8];
int
foo (void)
{
return __builtin_bswap32 (array[1]);
}
So before CSE, we have:
(insn 5 2 6 2 (set (reg/f:DI 121)
(symbol_ref:DI ("*.LANCHOR0") [flags 0x182]))
{*pcrel_local_addr})
(insn 6 5 7 2 (set (reg:DI 123)
(const_int 4 [0x4])) {*movdi_internal64})
(insn 7 6 8 2 (set (reg:SI 122)
(bswap:SI (mem/c:SI (plus:DI (reg/f:DI 121)
(reg:DI 123)))))
{bswapsi2_load}
(expr_list:REG_EQUAL (bswap:SI (mem/c:SI (plus:DI (reg/f:DI 121)
(const_int 4 [0x4]))))))
...
After CSE, we then have all the way up to LRA:
(insn 7 9 14 2 (set (reg:SI 122)
(bswap:SI (mem/c:SI (plus:DI (symbol_ref:DI ("*.LANCHOR0")
[flags 0x182])
(const_int 4))))) {bswapsi2_load})
...
LRA then calls decompse_address with the above address, which causes us to go
sideways. Not sure why yet. Maybe our bswap2_load pattern needs help?
