[Bug inline-asm/99015] New: ICE: Max. number of generated reload insns per insn is achieved (90)

[zhan3299 at purdue dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99015

            Bug ID: 99015
           Summary: ICE: Max. number of generated reload insns per insn is
                    achieved (90)
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: inline-asm
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhan3299 at purdue dot edu
  Target Milestone: ---

Another inline-asm issue causes an ICE.

--- poc.c starts ---
int main() {
    asm("" : : "fq"(.100));
}
--- poc.c ends ---

The version of GCC is 10.2.0 x86-64, and running 'gcc -O1 poc.c ' can trigger
the ICE.

--- error trace starts ---
$ gcc -O1 poc.c
during RTL pass: reload
test.c: In function ‘main’:
test.c:3:1: internal compiler error: maximum number of generated reload insns
per insn achieved (90)
    3 | }
      | ^
0x9fb0c0 lra_constraints(bool)
        ../../gcc/gcc/lra-constraints.c:4952
0x9e9314 lra(_IO_FILE*)
        ../../gcc/gcc/lra.c:2440
0x9a7201 do_reload
        ../../gcc/gcc/ira.c:5523
0x9a7201 execute
        ../../gcc/gcc/ira.c:5709
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
--- error trace ends ---


This issue only occurs when compiling with -O1 and higher, but does not with
-O0.

I also test other versions of GCC. It seems to affect GCC version 8.1 and
higher, but not version 7.5 and lower.


This issue may be similar with
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98991. However, as #98991
additionally affects GCC version 7.5 and lower, I suspect they are different.