https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112896
Bug ID: 112896
Summary: RISC-V: gcc.dg/pr30957-1.c run failure when
rv64gcv_zvl1024b_zvfh_zfh
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: pan2.li at intel dot com
Target Milestone: ---
The gcc.dg/pr30957-1.c test case is failed in RISC-V backend when build with
below options.
-march=rv64gcv_zvl1024b_zvfh_zfh -mabi=lp64d -O2 -mcmodel=medlow
--param=riscv-autovec-preference=fixed-vlmax -funroll-loops -fassociative-math
-fno-trapping-math -fno-signed-zeros -fvariable-expansion-in-unroller
-fdump-rtl-expand-details -lm gcc/testsuite/gcc.dg/pr30957-1.c -o test.elf
The test gcc/testsuite/gcc.dg/pr30957-1.c may be similar as below.
float __attribute__((noinline))
foo (float d, int n)
{
unsigned i;
float accum = d;
for (i = 0; i < n; i++)
accum += d;
return accum;
}
int
main ()
{
/* When compiling standard compliant we expect foo to return -0.0. But the
variable expansion during unrolling optimization (for this testcase
enabled
by non-compliant -fassociative-math) instantiates copy(s) of the
accumulator which it initializes with +0.0. Hence we expect that foo
returns +0.0. */
if (__builtin_copysignf (1.0, foo (0.0 / -5.0, 10)) != 1.0)
abort ();
exit (0);
}
Have an initial investigation that RISC-V backend always get LPT_NONE when
unroll_loops, as the step of loop will be dynamic after vectorizing, and get
the simple loop flag as false, then the pass unroll_loops will do nothing for
non simple loop.
We may need further investigation for this case.
