> Am 19.06.2023 um 19:03 schrieb Alexander Monakov <amona...@ispras.ru>:
>
>
> Ping. OK for trunk?
Ok if the FE maintainers do not object within 48h.
Thanks,
Richard
>> On Mon, 5 Jun 2023, Alexander Monakov wrote:
>>
>> Ping for the front-end maintainers' input.
>>
>>> On Mon, 22 May 2023, Richard Biener wrote:
>>>
>>> On Thu, May 18, 2023 at 11:04 PM Alexander Monakov via Gcc-patches
>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>
>>>> Implement -ffp-contract=on for C and C++ without changing default
>>>> behavior (=off for -std=cNN, =fast for C++ and -std=gnuNN).
>>>
>>> The documentation changes mention the defaults are changed for
>>> standard modes, I suppose you want to remove that hunk.
>>>
>>>> gcc/c-family/ChangeLog:
>>>>
>>>> * c-gimplify.cc (fma_supported_p): New helper.
>>>> (c_gimplify_expr) [PLUS_EXPR, MINUS_EXPR]: Implement FMA
>>>> contraction.
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>> * common.opt (fp_contract_mode) [on]: Remove fallback.
>>>> * config/sh/sh.md (*fmasf4): Correct flag_fp_contract_mode test.
>>>> * doc/invoke.texi (-ffp-contract): Update.
>>>> * trans-mem.cc (diagnose_tm_1): Skip internal function calls.
>>>> ---
>>>> gcc/c-family/c-gimplify.cc | 78 ++++++++++++++++++++++++++++++++++++++
>>>> gcc/common.opt | 3 +-
>>>> gcc/config/sh/sh.md | 2 +-
>>>> gcc/doc/invoke.texi | 8 ++--
>>>> gcc/trans-mem.cc | 3 ++
>>>> 5 files changed, 88 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc
>>>> index ef5c7d919f..f7635d3b0c 100644
>>>> --- a/gcc/c-family/c-gimplify.cc
>>>> +++ b/gcc/c-family/c-gimplify.cc
>>>> @@ -41,6 +41,8 @@ along with GCC; see the file COPYING3. If not see
>>>> #include "c-ubsan.h"
>>>> #include "tree-nested.h"
>>>> #include "context.h"
>>>> +#include "tree-pass.h"
>>>> +#include "internal-fn.h"
>>>>
>>>> /* The gimplification pass converts the language-dependent trees
>>>> (ld-trees) emitted by the parser into language-independent trees
>>>> @@ -686,6 +688,14 @@ c_build_bind_expr (location_t loc, tree block, tree
>>>> body)
>>>> return bind;
>>>> }
>>>>
>>>> +/* Helper for c_gimplify_expr: test if target supports fma-like FN. */
>>>> +
>>>> +static bool
>>>> +fma_supported_p (enum internal_fn fn, tree type)
>>>> +{
>>>> + return direct_internal_fn_supported_p (fn, type, OPTIMIZE_FOR_BOTH);
>>>> +}
>>>> +
>>>> /* Gimplification of expression trees. */
>>>>
>>>> /* Do C-specific gimplification on *EXPR_P. PRE_P and POST_P are as in
>>>> @@ -739,6 +749,74 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p
>>>> ATTRIBUTE_UNUSED,
>>>> break;
>>>> }
>>>>
>>>> + case PLUS_EXPR:
>>>> + case MINUS_EXPR:
>>>> + {
>>>> + tree type = TREE_TYPE (*expr_p);
>>>> + /* For -ffp-contract=on we need to attempt FMA contraction only
>>>> + during initial gimplification. Late contraction across
>>>> statement
>>>> + boundaries would violate language semantics. */
>>>> + if (SCALAR_FLOAT_TYPE_P (type)
>>>> + && flag_fp_contract_mode == FP_CONTRACT_ON
>>>> + && cfun && !(cfun->curr_properties & PROP_gimple_any)
>>>> + && fma_supported_p (IFN_FMA, type))
>>>> + {
>>>> + bool neg_mul = false, neg_add = code == MINUS_EXPR;
>>>> +
>>>> + tree *op0_p = &TREE_OPERAND (*expr_p, 0);
>>>> + tree *op1_p = &TREE_OPERAND (*expr_p, 1);
>>>> +
>>>> + /* Look for ±(x * y) ± z, swapping operands if necessary. */
>>>> + if (TREE_CODE (*op0_p) == NEGATE_EXPR
>>>> + && TREE_CODE (TREE_OPERAND (*op0_p, 0)) == MULT_EXPR)
>>>> + /* '*EXPR_P' is '-(x * y) ± z'. This is fine. */;
>>>> + else if (TREE_CODE (*op0_p) != MULT_EXPR)
>>>> + {
>>>> + std::swap (op0_p, op1_p);
>>>> + std::swap (neg_mul, neg_add);
>>>> + }
>>>> + if (TREE_CODE (*op0_p) == NEGATE_EXPR)
>>>> + {
>>>> + op0_p = &TREE_OPERAND (*op0_p, 0);
>>>> + neg_mul = !neg_mul;
>>>> + }
>>>> + if (TREE_CODE (*op0_p) != MULT_EXPR)
>>>> + break;
>>>> + auto_vec<tree, 3> ops (3);
>>>> + ops.quick_push (TREE_OPERAND (*op0_p, 0));
>>>> + ops.quick_push (TREE_OPERAND (*op0_p, 1));
>>>> + ops.quick_push (*op1_p);
>>>> +
>>>> + enum internal_fn ifn = IFN_FMA;
>>>> + if (neg_mul)
>>>> + {
>>>> + if (fma_supported_p (IFN_FNMA, type))
>>>> + ifn = IFN_FNMA;
>>>> + else
>>>> + ops[0] = build1 (NEGATE_EXPR, type, ops[0]);
>>>> + }
>>>> + if (neg_add)
>>>> + {
>>>> + enum internal_fn ifn2 = ifn == IFN_FMA ? IFN_FMS :
>>>> IFN_FNMS;
>>>> + if (fma_supported_p (ifn2, type))
>>>> + ifn = ifn2;
>>>> + else
>>>> + ops[2] = build1 (NEGATE_EXPR, type, ops[2]);
>>>> + }
>>>> + for (auto &&op : ops)
>>>> + if (gimplify_expr (&op, pre_p, post_p, is_gimple_val,
>>>> fb_rvalue)
>>>> + == GS_ERROR)
>>>> + return GS_ERROR;
>>>> +
>>>> + gcall *call = gimple_build_call_internal_vec (ifn, ops);
>>>> + gimple_seq_add_stmt_without_update (pre_p, call);
>>>> + *expr_p = create_tmp_var (type);
>>>> + gimple_call_set_lhs (call, *expr_p);
>>>
>>> it would be possible to do
>>>
>>> *expr_p = build_call_expr_internal (ifn, type, ops[0], ops[1]. ops[2]);
>>> return GS_OK;
>>>
>>> and not worry about temporary creation and gimplifying of the operands.
>>> That would in theory also leave the possibility to do this during
>>> genericization instead (and avoid the guard against late invocation of
>>> the hook).
>>>
>>> Otherwise it looks OK, but I'll let frontend maintainers have a chance to
>>> look
>>> as well.
>>>
>>> Thanks for tackling this long-standing issue.
>>> Richard.
>>>
>>>> + return GS_ALL_DONE;
>>>> + }
>>>> + break;
>>>> + }
>>>> +
>>>> default:;
>>>> }
>>>>
>>>> diff --git a/gcc/common.opt b/gcc/common.opt
>>>> index a28ca13385..3daec85aef 100644
>>>> --- a/gcc/common.opt
>>>> +++ b/gcc/common.opt
>>>> @@ -1662,9 +1662,8 @@ Name(fp_contract_mode) Type(enum fp_contract_mode)
>>>> UnknownError(unknown floating
>>>> EnumValue
>>>> Enum(fp_contract_mode) String(off) Value(FP_CONTRACT_OFF)
>>>>
>>>> -; Not implemented, fall back to conservative FP_CONTRACT_OFF.
>>>> EnumValue
>>>> -Enum(fp_contract_mode) String(on) Value(FP_CONTRACT_OFF)
>>>> +Enum(fp_contract_mode) String(on) Value(FP_CONTRACT_ON)
>>>>
>>>> EnumValue
>>>> Enum(fp_contract_mode) String(fast) Value(FP_CONTRACT_FAST)
>>>> diff --git a/gcc/config/sh/sh.md b/gcc/config/sh/sh.md
>>>> index 4622dba012..5cb1795482 100644
>>>> --- a/gcc/config/sh/sh.md
>>>> +++ b/gcc/config/sh/sh.md
>>>> @@ -9269,7 +9269,7 @@ (define_insn_and_split "*fmasf4"
>>>> (match_operand:SF 3 "arith_reg_operand" "0")))
>>>> (clobber (reg:SI FPSCR_STAT_REG))
>>>> (use (reg:SI FPSCR_MODES_REG))]
>>>> - "TARGET_SH2E && flag_fp_contract_mode != FP_CONTRACT_OFF"
>>>> + "TARGET_SH2E && flag_fp_contract_mode == FP_CONTRACT_FAST"
>>>> "fmac %1,%2,%0"
>>>> "&& can_create_pseudo_p ()"
>>>> [(parallel [(set (match_dup 0)
>>>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>>>> index b92b857602..cb1e9a1d9f 100644
>>>> --- a/gcc/doc/invoke.texi
>>>> +++ b/gcc/doc/invoke.texi
>>>> @@ -11983,10 +11983,12 @@ This option is enabled by default at
>>>> optimization levels @option{-O1},
>>>> such as forming of fused multiply-add operations if the target has
>>>> native support for them.
>>>> @option{-ffp-contract=on} enables floating-point expression contraction
>>>> -if allowed by the language standard. This is currently not implemented
>>>> -and treated equal to @option{-ffp-contract=off}.
>>>> +if allowed by the language standard. This is implemented for C and C++,
>>>> +where it enables contraction within one expression, but not across
>>>> +different statements.
>>>>
>>>> -The default is @option{-ffp-contract=fast}.
>>>> +The default is @option{-ffp-contract=off} for C in a standards compliant
>>>> mode
>>>> +(@option{-std=c11} or similar), @option{-ffp-contract=fast} otherwise.
>>>>
>>>> @opindex fomit-frame-pointer
>>>> @item -fomit-frame-pointer
>>>> diff --git a/gcc/trans-mem.cc b/gcc/trans-mem.cc
>>>> index 4b129663e0..2174faef4c 100644
>>>> --- a/gcc/trans-mem.cc
>>>> +++ b/gcc/trans-mem.cc
>>>> @@ -637,6 +637,9 @@ diagnose_tm_1 (gimple_stmt_iterator *gsi, bool
>>>> *handled_ops_p,
>>>> {
>>>> case GIMPLE_CALL:
>>>> {
>>>> + if (gimple_call_internal_p (stmt))
>>>> + break;
>>>> +
>>>> tree fn = gimple_call_fn (stmt);
>>>>
>>>> if ((d->summary_flags & DIAG_TM_OUTER) == 0
>>>> --
>>>> 2.39.2
>>>>
Re: [PATCH] c-family: implement -ffp-contract=on
Richard Biener via Gcc-patches Mon, 19 Jun 2023 11:23:48 -0700
- Re: [PATCH] c-family: implement -ffp-con... Alexander Monakov via Gcc-patches
- Re: [PATCH] c-family: implement -ff... Richard Biener via Gcc-patches
- Re: [PATCH] c-family: implement... Alexander Monakov via Gcc-patches
- Re: [PATCH] c-family: implement -ff... Alexander Monakov via Gcc-patches
- Re: [PATCH] c-family: implement... Alexander Monakov via Gcc-patches
- Re: [PATCH] c-family: imple... Richard Biener via Gcc-patches
