On Fri, Sep 27, 2024 at 9:52 AM <pan2...@intel.com> wrote:
>
> From: Pan Li <pan2...@intel.com>
>
> We iterate all phi node of bb to try to match the SAT_* pattern
> for scalar integer. We also remove the phi mode when the relevant
> pattern matched.
>
> Unfortunately the iterator may have no idea the phi node is removed
> and continue leverage the free data and then ICE similar as below.
>
> [0] psi ptr 0x75216340c000
> [0] psi ptr 0x75216340c400
> [1] psi ptr 0xa5a5a5a5a5a5a5a5 <=== GC freed pointer.
>
> during GIMPLE pass: widening_mul
> tmp.c: In function ‘f’:
> tmp.c:45:6: internal compiler error: Segmentation fault
> 45 | void f(int rows, int cols) {
> | ^
> 0x36e2788 internal_error(char const*, ...)
> ../../gcc/diagnostic-global-context.cc:517
> 0x18005f0 crash_signal
> ../../gcc/toplev.cc:321
> 0x752163c4531f ???
> ./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0
> 0x103ae0e bool is_a_helper<gphi*>::test<gimple>(gimple*)
> ../../gcc/gimple.h:1256
> 0x103f9a5 bool is_a<gphi*, gimple>(gimple*)
> ../../gcc/is-a.h:232
> 0x103dc78 gphi* as_a<gphi*, gimple>(gimple*)
> ../../gcc/is-a.h:255
> 0x104f12e gphi_iterator::phi() const
> ../../gcc/gimple-iterator.h:47
> 0x1a57bef after_dom_children
> ../../gcc/tree-ssa-math-opts.cc:6140
> 0x3344482 dom_walker::walk(basic_block_def*)
> ../../gcc/domwalk.cc:354
> 0x1a58601 execute
> ../../gcc/tree-ssa-math-opts.cc:6312
>
> This patch would like to fix the iterate on modified collection problem
> by backup the next phi in advance.
>
> The below test suites are passed for this patch.
> * The rv64gcv fully regression test.
> * The x86 bootstrap test.
> * The x86 fully regression test.
OK.
Thanks,
Richard.
> PR middle-end/116861
>
> gcc/ChangeLog:
>
> * tree-ssa-math-opts.cc (math_opts_dom_walker::after_dom_children):
> Backup
> the next psi iterator before remove the phi node.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/torture/pr116861-1.c: New test.
>
> Signed-off-by: Pan Li <pan2...@intel.com>
> ---
> gcc/testsuite/gcc.dg/torture/pr116861-1.c | 76 +++++++++++++++++++++++
> gcc/tree-ssa-math-opts.cc | 9 ++-
> 2 files changed, 83 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/pr116861-1.c
>
> diff --git a/gcc/testsuite/gcc.dg/torture/pr116861-1.c
> b/gcc/testsuite/gcc.dg/torture/pr116861-1.c
> new file mode 100644
> index 00000000000..7dcfe664d89
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr116861-1.c
> @@ -0,0 +1,76 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +void pm_message(void);
> +struct CmdlineInfo {
> + _Bool wantCrop[4];
> + unsigned int margin;
> +};
> +typedef struct {
> + unsigned int removeSize;
> +} CropOp;
> +typedef struct {
> + CropOp op[4];
> +} CropSet;
> +static void divideAllBackgroundIntoBorders(unsigned int const totalSz,
> + _Bool const wantCropSideA,
> + _Bool const wantCropSideB,
> + unsigned int const wantMargin,
> + unsigned int *const sideASzP,
> + unsigned int *const sideBSzP) {
> + unsigned int sideASz, sideBSz;
> + if (wantCropSideA && wantCropSideB)
> + {
> + sideASz = totalSz / 2;
> + if (wantMargin)
> + sideBSz = totalSz - sideASz;
> + }
> + else if (wantCropSideB)
> + {
> + sideBSz = 0;
> + }
> + *sideASzP = sideASz;
> + *sideBSzP = sideBSz;
> +}
> +static CropOp oneSideCrop(_Bool const wantCrop, unsigned int const borderSz,
> + unsigned int const margin) {
> + CropOp retval;
> + if (wantCrop)
> + {
> + if (borderSz >= margin)
> + retval.removeSize = borderSz - margin;
> + else
> + retval.removeSize = 0;
> + }
> + return retval;
> +}
> +struct CmdlineInfo cmdline1;
> +void f(int rows, int cols) {
> + struct CmdlineInfo cmdline0 = cmdline1;
> + CropSet crop;
> + struct CmdlineInfo cmdline = cmdline0;
> + CropSet retval;
> + unsigned int leftBorderSz, rghtBorderSz;
> + unsigned int topBorderSz, botBorderSz;
> + divideAllBackgroundIntoBorders(cols, cmdline.wantCrop[0],
> + cmdline.wantCrop[1], cmdline.margin > 0,
> + &leftBorderSz, &rghtBorderSz);
> + divideAllBackgroundIntoBorders(rows, cmdline.wantCrop[2],
> + cmdline.wantCrop[3], cmdline.margin > 0,
> + &topBorderSz, &botBorderSz);
> + retval.op[0] =
> + oneSideCrop(cmdline.wantCrop[0], leftBorderSz, cmdline.margin);
> + retval.op[1] =
> + oneSideCrop(cmdline.wantCrop[1], rghtBorderSz, cmdline.margin);
> + retval.op[2] =
> + oneSideCrop(cmdline.wantCrop[2], topBorderSz, cmdline.margin);
> + retval.op[3] =
> + oneSideCrop(cmdline.wantCrop[3], botBorderSz, cmdline.margin);
> + crop = retval;
> + unsigned int i = 0;
> + for (i = 0; i < 4; ++i)
> + {
> + if (crop.op[i].removeSize == 0)
> + pm_message();
> + }
> +}
> diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
> index 8c622514dbd..f1cfe7dfab0 100644
> --- a/gcc/tree-ssa-math-opts.cc
> +++ b/gcc/tree-ssa-math-opts.cc
> @@ -6129,10 +6129,15 @@ math_opts_dom_walker::after_dom_children (basic_block
> bb)
>
> fma_deferring_state fma_state (param_avoid_fma_max_bits > 0);
>
> - for (gphi_iterator psi = gsi_start_phis (bb); !gsi_end_p (psi);
> - gsi_next (&psi))
> + for (gphi_iterator psi_next, psi = gsi_start_phis (bb); !gsi_end_p (psi);
> + psi = psi_next)
> {
> + psi_next = psi;
> + gsi_next (&psi_next);
> +
> gimple_stmt_iterator gsi = gsi_after_labels (bb);
> +
> + /* The match_* may remove phi node. */
> match_saturation_add (&gsi, psi.phi ());
> match_unsigned_saturation_sub (&gsi, psi.phi ());
> }
> --
> 2.43.0
>
