RE: [PATCH][vect]: Fix null dereference in boolean reductions [PR122475]

> -----Original Message-----
> From: Andrea Pinski <[email protected]>
> Sent: 13 August 2026 21:27
> To: Tamar Christina <[email protected]>
> Cc: [email protected]; nd <[email protected]>; [email protected];
> [email protected]
> Subject: Re: [PATCH][vect]: Fix null dereference in boolean reductions
> [PR122475]
> 
> On Mon, Nov 3, 2025 at 12:10 AM Tamar Christina
> <[email protected]> wrote:
> >
> > neutral_op can be null, so guard against that.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu,
> > arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
> > -m32, -m64 and no issues
> >
> > Pushed to master.
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> >         PR tree-optimization/122475
> >         * tree-vect-loop.cc (vectorizable_reduction): Check for neutral_op.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         PR tree-optimization/122475
> >         * gcc.dg/vect/pr122475.c: New test.
> >         * gcc.target/aarch64/sve/vect-reduc-bool-19.c: New test.
> >         * gcc.target/aarch64/sve/vect-reduc-bool-20.c: New test.
> >
> > ---
> > diff --git a/gcc/testsuite/gcc.dg/vect/pr122475.c
> b/gcc/testsuite/gcc.dg/vect/pr122475.c
> > new file mode 100644
> > index
> 0000000000000000000000000000000000000000..ed229c5475cc96fc0ef
> 3beea71b101db89e08916
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/vect/pr122475.c
> > @@ -0,0 +1,13 @@
> > +/* { dg-additional-options "-march=armv8-a+sve" { target aarch64*-*-* } }
> */
> > +/* Check that we don't ICE.  */
> > +int a;
> > +int b;
> > +int main() {
> > +  for (char t = 0; t < 14; t += 2)
> > +    for (int u = 0; u < 242; u += 4) {
> > +      a = a < 0 ? a : 0;
> > +      b = b < 0 ? b : 0;
> > +    }
> > +}
> > +
> > +/* { dg-final { scan-tree-dump-times "optimized: loop vectorized" 1 "vect" {
> target aarch64*-*-* } } } */
> 
> I only noticed this failure now (sorry) But the above testcase fails
> at execution if the target does not have sve support on it.

Hmm it's not meant to be one (hence also no tree-vect.h import), but the vect.exp
testsuite misdetected it as one because of the "main" function. I'll fix tomorrow.

Thanks,
Tamar

> 
> Thanks,
> Andrea
> 
> 
> > diff --git a/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-19.c
> b/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-19.c
> > new file mode 100644
> > index
> 0000000000000000000000000000000000000000..6492c44c065159d06d
> 7e69499dfc9834721d62ef
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-19.c
> > @@ -0,0 +1,17 @@
> > +/* { dg-do compile } */
> > +/* { dg-additional-options "-mautovec-preference=sve-only -fdump-tree-
> vect-details -O3 --param vect-epilogues-nomask=0" } */
> > +
> > +int p[128];
> > +
> > +bool __attribute__((noipa))
> > +fand (int n, bool r1, bool r2)
> > +{
> > +  bool r = true;
> > +  for (int i = 0; i < (n/2); i+=2)
> > +    {
> > +      r &= (p[i] != 0) & r1;
> > +      r &= (p[i+1] != 0) & r2;
> > +    }
> > +  return r;
> > +}
> > +/* { dg-final { scan-tree-dump-times "optimized: loop vectorized" 1 "vect" }
> } */
> > diff --git a/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-20.c
> b/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-20.c
> > new file mode 100644
> > index
> 0000000000000000000000000000000000000000..83c5c206dd2597c377
> 6317005a3dd38ee5991f16
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/vect-reduc-bool-20.c
> > @@ -0,0 +1,32 @@
> > +/* { dg-do compile } */
> > +/* { dg-additional-options "-mautovec-preference=sve-only -fdump-tree-
> vect-details -O3 --param vect-epilogues-nomask=0" } */
> > +
> > +#include <stdbool.h>
> > +#include <stdint.h>
> > +
> > +void vec_slp_cmp (char* restrict a, char* restrict b, int n) {
> > +    bool x0 = b[0] != 0;
> > +    bool x1 = b[1] != 0;
> > +    bool x2 = b[2] != 0;
> > +    bool x3 = b[3] != 0;
> > +    for (int i = 0; i < n; ++i) {
> > +        x0 &= (a[i * 4] != 0);
> > +        x1 &= (a[i * 4 + 1] != 0);
> > +        x2 &= (a[i * 4 + 2] != 0);
> > +        x3 &= (a[i * 4 + 3] != 0);
> > +    }
> > +    b[0] = x0;
> > +    b[1] = x1;
> > +    b[2] = x2;
> > +    b[3] = x3;
> > +}
> > +
> > +void vec_slp_cmp1 (char* restrict a, char* restrict b, int n) {
> > +    bool x0 = b[0] != 0;
> > +    for (int i = 0; i < n; ++i) {
> > +        x0 &= (a[i] != 0);
> > +    }
> > +    b[0] = x0;
> > +}
> > +
> > +/* { dg-final { scan-tree-dump-times "optimized: loop vectorized" 2 "vect" {
> target aarch64*-*-* } } } */
> > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> > index
> 50cdc2a90fa29c1e0d116c0589bc246e6d8fcc84..576a69c82d25aa74ce9cc8
> dbb89d0b340ed9ba39 100644
> > --- a/gcc/tree-vect-loop.cc
> > +++ b/gcc/tree-vect-loop.cc
> > @@ -7578,7 +7578,9 @@ vectorizable_reduction (loop_vec_info
> loop_vinfo,
> >    if ((double_reduc || neutral_op)
> >        && !nunits_out.is_constant ()
> >        && (SLP_TREE_LANES (slp_node) != 1 && !reduc_chain)
> > -      && !operand_equal_p (neutral_op, vect_phi_initial_value
> (reduc_def_phi))
> > +      && (!neutral_op
> > +         || !operand_equal_p (neutral_op,
> > +                              vect_phi_initial_value (reduc_def_phi)))
> >        && !direct_internal_fn_supported_p (IFN_VEC_SHL_INSERT,
> >                                           vectype_out, OPTIMIZE_FOR_SPEED))
> >      {
> >
> >
> > --