On Thu, Jun 15, 2023 at 8:18 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Match will query ranger via tree_nonzero_bits/get_nonzero_bits for 2 and 3rd
> operand of the COND_EXPR and phiopt tries to do create the COND_EXPR even if
> we moving
> one statement. That one statement could have some flow sensitive information
> on it
> based on the condition that is for the COND_EXPR but that might create wrong
> code
> if the statement was moved out.
>
> So the solution here is to temporarily remove the flow sensitive info of the
> statements
> phiopt might move and try match only then. This is done via the new class
> auto_flow_sensitive.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
Ah, looks like I forgot about pt->null in the approach used by
maybe_fold_comparisons_from_match_pd.
That also has much less control over which stmts are possibly under
conditional control
so your approach might be simpler for phiopt. Note the flow-sensitive
info is on SSA defs
and some stmts have multiple of those so I think the auto_ class
should construct on SSA defs
instead. Can you make it a non-auto (POD?) class so I can possibly re-use it in
the maybe_fold_comparisons_from_match_pd machinery though? Like
class flow_sensitive_info_storage
{
public:
save (tree);
save_and_clear (tree);
restore (tree);
private:
... members ...
};
?
> PR tree-optimization/110252
>
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.cc (match_simplify_replacement): Temporarily
> remove the flow sensitive info on the two statements that might
> be moved.
> * tree-ssanames.cc (auto_flow_sensitive::auto_flow_sensitive): New
> method.
> (auto_flow_sensitive::~auto_flow_sensitive): New method.
> * tree-ssanames.h (class auto_flow_sensitive): New class.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.c-torture/execute/pr110252.c: New test.
> * gcc.c-torture/execute/pr110252-1.c: New test.
> * gcc.dg/tree-ssa/phi-opt-25b.c: Updated as
> __builtin_parity loses the nonzerobits info.
> ---
> .../gcc.c-torture/execute/pr110252-1.c | 15 +++++++
> .../gcc.c-torture/execute/pr110252.c | 10 +++++
> gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25b.c | 6 +--
> gcc/tree-ssa-phiopt.cc | 12 ++++--
> gcc/tree-ssanames.cc | 40 +++++++++++++++++++
> gcc/tree-ssanames.h | 21 ++++++++++
> 6 files changed, 97 insertions(+), 7 deletions(-)
> create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr110252-1.c
> create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr110252.c
>
> diff --git a/gcc/testsuite/gcc.c-torture/execute/pr110252-1.c
> b/gcc/testsuite/gcc.c-torture/execute/pr110252-1.c
> new file mode 100644
> index 00000000000..4ae93ca0647
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/pr110252-1.c
> @@ -0,0 +1,15 @@
> +/* This is reduced from sel-sched.cc which was noticed was being miscompiled
> too. */
> +int g(int min_need_stall) __attribute__((__noipa__));
> +int g(int min_need_stall)
> +{
> + return min_need_stall < 0 ? 1 : ((min_need_stall) < (1) ?
> (min_need_stall) : (1));
> +}
> +int main(void)
> +{
> + for(int i = -100; i <= 100; i++)
> + {
> + int t = g(i);
> + if (t != (i!=0))
> + __builtin_abort();
> + }
> +}
> diff --git a/gcc/testsuite/gcc.c-torture/execute/pr110252.c
> b/gcc/testsuite/gcc.c-torture/execute/pr110252.c
> new file mode 100644
> index 00000000000..7f1a7dbf134
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/pr110252.c
> @@ -0,0 +1,10 @@
> +signed char f() __attribute__((__noipa__));
> +signed char f() { return 0; }
> +int main()
> +{
> + int g = f() - 1;
> + int e = g < 0 ? 1 : ((g >> (8-2))!=0);
> + asm("":"+r"(e));
> + if (e != 1)
> + __builtin_abort();
> +}
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25b.c
> b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25b.c
> index 7298da0c96e..0fd9b004a03 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25b.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25b.c
> @@ -65,8 +65,6 @@ int test_popcountll(unsigned long long x, unsigned long
> long y)
> return x ? __builtin_popcountll(y) : 0;
> }
>
> -/* 3 types of functions (not including parity), each with 3 types and there
> are 2 goto each */
> -/* { dg-final { scan-tree-dump-times "goto " 18 "optimized" } } */
> +/* 4 types of functions, each with 3 types and there are 2 goto each */
> +/* { dg-final { scan-tree-dump-times "goto " 24 "optimized" } } */
> /* { dg-final { scan-tree-dump-times "x_..D. != 0" 12 "optimized" } } */
> -/* parity case will be optimized to x!=0 & parity(y) . */
> -/* { dg-final { scan-tree-dump-times " & " 3 "optimized" } } */
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index d9a1153086f..5f871e019e4 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -782,9 +782,15 @@ match_simplify_replacement (basic_block cond_bb,
> basic_block middle_bb,
> }
>
> tree type = TREE_TYPE (gimple_phi_result (phi));
> - result = gimple_simplify_phiopt (early_p, type, stmt,
> - arg_true, arg_false,
> - &seq);
> + {
> + auto_flow_sensitive s1(stmt_to_move);
> + auto_flow_sensitive s_alt(stmt_to_move_alt);
> +
> + result = gimple_simplify_phiopt (early_p, type, stmt,
> + arg_true, arg_false,
> + &seq);
> + }
> +
> if (!result)
> return false;
>
> diff --git a/gcc/tree-ssanames.cc b/gcc/tree-ssanames.cc
> index 5fdb6a37e9f..765d343ba49 100644
> --- a/gcc/tree-ssanames.cc
> +++ b/gcc/tree-ssanames.cc
> @@ -812,6 +812,46 @@ reset_flow_sensitive_info_in_bb (basic_block bb)
> }
> }
>
> +/* Constructor for auto_flow_sensitive. Saves
> + off the ssa name's flow sensitive information
> + that was defined by gimple statement S and
> + resets it to be non-flow based ones. */
> +auto_flow_sensitive::auto_flow_sensitive (gimple *s)
> +{
> + if (!s)
> + return;
> +
> + name = gimple_get_lhs (s);
> +
> + if (!POINTER_TYPE_P (TREE_TYPE (name)))
> + {
> + range_info = SSA_NAME_RANGE_INFO (name);
> + SSA_NAME_RANGE_INFO (name) = NULL;
> + }
> + else if (SSA_NAME_PTR_INFO (name))
> + {
> + get_ptr_info_alignment (SSA_NAME_PTR_INFO (name), &align, &misalign);
> + null = SSA_NAME_PTR_INFO (name)->pt.null;
> + }
> +}
> +
> +/* Deconstructor, restores the flow sensitive information
> + for the SSA name. */
> +auto_flow_sensitive::~auto_flow_sensitive ()
> +{
> + if (!name)
> + return;
> +
> + if (!POINTER_TYPE_P (TREE_TYPE (name)))
> + SSA_NAME_RANGE_INFO (name) = range_info;
> + else if (SSA_NAME_PTR_INFO (name))
> + {
> + if (align)
> + set_ptr_info_alignment (SSA_NAME_PTR_INFO (name), align, misalign);
> + SSA_NAME_PTR_INFO (name)->pt.null = null;
> + }
> +}
> +
> /* Release all the SSA_NAMEs created by STMT. */
>
> void
> diff --git a/gcc/tree-ssanames.h b/gcc/tree-ssanames.h
> index f3fa609208a..28b83b779fa 100644
> --- a/gcc/tree-ssanames.h
> +++ b/gcc/tree-ssanames.h
> @@ -137,4 +137,25 @@ make_temp_ssa_name (tree type, gimple *stmt, const char
> *name)
> }
>
>
> +/* RAII style class to temporarily remove flow sensitive
> + from a ssa name defined by a gimple statement.
> + An usage example is inside phiopt, where using match-and-simplify
> + but since the statement is from inside a conditional bb, the
> + flow sensitive information can't be used. */
> +class auto_flow_sensitive
> +{
> +public:
> + auto_flow_sensitive (gimple *s);
> + ~auto_flow_sensitive ();
> +private:
> + tree name = nullptr;
> + /* The range info for non pointers */
> + vrange_storage *range_info;
> + /* Flow sensitive pointer information. */
> + unsigned int align = 0;
> + unsigned int misalign = 0;
> + bool null = false;
> +};
> +
> +
> #endif /* GCC_TREE_SSANAMES_H */
> --
> 2.31.1
>
