This fixes a mistake done with r8-5008 when introducing allow_peel to the unroll code. The intent was to allow peeling that doesn't grow code but the result was that with -O3 and UL_ALL this wasn't done. The following instantiates the desired effect by adjusting ul to UL_NO_GROWTH if peeling is not allowed.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed. 2022-01-05 Richard Biener <rguent...@suse.de> PR tree-optimization/100359 * tree-ssa-loop-ivcanon.c (try_unroll_loop_completely): Allow non-growing peeling with !allow_peel and UL_ALL. * gcc.dg/tree-ssa/pr100359.c: New testcase. --- gcc/testsuite/gcc.dg/tree-ssa/pr100359.c | 31 ++++++++++++++++++++++++ gcc/tree-ssa-loop-ivcanon.c | 6 ++++- 2 files changed, 36 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr100359.c diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr100359.c b/gcc/testsuite/gcc.dg/tree-ssa/pr100359.c new file mode 100644 index 00000000000..29243522caa --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr100359.c @@ -0,0 +1,31 @@ +/* { dg-do link } */ +/* { dg-options "-O3 -fdump-tree-cunrolli-optimized" } */ + +extern void foo(void); +static int b, f, *a = &b; +int **c = &a; +static void d() { + int g, h; + for (f = 0; f < 1; f++) { + int *i = &b; + { + int *j[3], **k = &a; + for (g = 0; g < 3; g++) + for (h = 0; h < 1; h++) + j[g] = &b; + *k = j[0]; + } + *c = i; + } +} +int main() { + d(); + *a = 0; + if (**c) + foo(); + return 0; +} + +/* Verify that we unroll the inner loop early even with -O3. */ +/* { dg-final { scan-tree-dump "loop with 1 iterations completely unrolled" "cunrolli" } } */ +/* { dg-final { scan-tree-dump "loop with 3 iterations completely unrolled" "cunrolli" } } */ diff --git a/gcc/tree-ssa-loop-ivcanon.c b/gcc/tree-ssa-loop-ivcanon.c index 4f1e3537f05..e2ac2044741 100644 --- a/gcc/tree-ssa-loop-ivcanon.c +++ b/gcc/tree-ssa-loop-ivcanon.c @@ -720,7 +720,7 @@ try_unroll_loop_completely (class loop *loop, exit = NULL; /* See if we can improve our estimate by using recorded loop bounds. */ - if ((allow_peel || maxiter == 0 || ul == UL_NO_GROWTH) + if ((maxiter == 0 || ul != UL_SINGLE_ITER) && maxiter >= 0 && (!n_unroll_found || (unsigned HOST_WIDE_INT)maxiter < n_unroll)) { @@ -729,6 +729,10 @@ try_unroll_loop_completely (class loop *loop, /* Loop terminates before the IV variable test, so we cannot remove it in the last iteration. */ edge_to_cancel = NULL; + /* If we do not allow peeling and we iterate just allow cases + that do not grow code. */ + if (!allow_peel && maxiter != 0) + ul = UL_NO_GROWTH; } if (!n_unroll_found) -- 2.31.1