Re: [r17-2064 Regression] FAIL: gcc.dg/tree-ssa/predcom-8.c scan-tree-dump-not pcom "Invalid sum" on Linux/x86_64

Hi, thanks for the report

I believe these are pre-existing failures that I turned into ICE's with 
my prior patch (https://gcc.gnu.org/r17-2050-g4e0964279b73d3) that this 
patch fixed and re-exposed.

KR,
Alfie

On 02/07/2026 12:56, Haochen Jiang wrote:
> On Linux/x86_64,
> 
> 470f86dd50a8adedbaa6ae9468bf42bfe89d1a36 is the first bad commit
> commit 470f86dd50a8adedbaa6ae9468bf42bfe89d1a36
> Author: Alfie Richards <[email protected]>
> Date:   Wed Jul 1 16:01:03 2026 +0000
> 
>      fix: Check if loop_vinfo is null before dereferencing.
> 
> caused
> 
> FAIL: gcc.dg/tree-ssa/predcom-8.c scan-tree-dump-not pcom "Invalid sum"
> FAIL: gcc.dg/vect/no-section-anchors-vect-31.c -flto -ffat-lto-objects  scan-tree-dump-times vect "Alignment of access forced using peeling" 2
> FAIL: gcc.dg/vect/no-section-anchors-vect-31.c -flto -ffat-lto-objects  scan-tree-dump-times vect "Vectorizing an unaligned access" 0
> FAIL: gcc.dg/vect/no-section-anchors-vect-31.c scan-tree-dump-times vect "Alignment of access forced using peeling" 2
> FAIL: gcc.dg/vect/no-section-anchors-vect-31.c scan-tree-dump-times vect "Vectorizing an unaligned access" 0
> FAIL: gcc.dg/vect/no-section-anchors-vect-64.c -flto -ffat-lto-objects  scan-tree-dump-times vect "Alignment of access forced using peeling" 2
> FAIL: gcc.dg/vect/no-section-anchors-vect-64.c -flto -ffat-lto-objects  scan-tree-dump-times vect "Vectorizing an unaligned access" 0
> FAIL: gcc.dg/vect/no-section-anchors-vect-64.c scan-tree-dump-times vect "Alignment of access forced using peeling" 2
> FAIL: gcc.dg/vect/no-section-anchors-vect-64.c scan-tree-dump-times vect "Vectorizing an unaligned access" 0
> FAIL: gcc.dg/vect/vect-56.c -flto -ffat-lto-objects  scan-tree-dump-not optimized "Invalid sum"
> FAIL: gcc.dg/vect/vect-56.c scan-tree-dump-not optimized "Invalid sum"
> 
> with GCC configured with
> 
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-2064/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap
> 
> To reproduce:
> 
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="tree-ssa.exp=gcc.dg/tree-ssa/predcom-8.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="tree-ssa.exp=gcc.dg/tree-ssa/predcom-8.c --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/no-section-anchors-vect-31.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/no-section-anchors-vect-31.c --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/no-section-anchors-vect-64.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/no-section-anchors-vect-64.c --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/vect-56.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/vect-56.c --target_board='unix{-m64\ -march=cascadelake}'"
> 
> (Please directly reply to this email for question about this report.)
> (If you met problems with cascadelake related, disabling AVX512F in command line might save that.)
> (However, please make sure that there is no potential problems with AVX512.)