[4/6] Support -fexcess-precision=16 which will enable FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 when backend supports _Float16.

Message ID	20210802063116.999830-5-hongtao.liu@intel.com
State	New
Headers	show Return-Path: <gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org> DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6ED3E387549C To: gcc-patches@gcc.gnu.org Subject: [PATCH 4/6] Support -fexcess-precision=16 which will enable FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 when backend supports _Float16. Date: Mon, 2 Aug 2021 14:31:14 +0800 Message-Id: <20210802063116.999830-5-hongtao.liu@intel.com> In-Reply-To: <20210802063116.999830-1-hongtao.liu@intel.com> References: <CAMZc-bwC4w1k0n2cUBezS_QPaj2pLzw2pJxwtf-avGWVX7YVFg@mail.gmail.com> <20210802063116.999830-1-hongtao.liu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: list From: liuhongt via Gcc-patches <gcc-patches@gcc.gnu.org> Reply-To: liuhongt <hongtao.liu@intel.com> Cc: joseph@codesourcery.com Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" <gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org>
Series	Initial support for AVX512FP16 \| expand [V3,0/6] Initial support for AVX512FP16 [1/6] Update hf soft-fp from glibc. [2/6,i386] Enable _Float16 type for TARGET_SSE2 and above. [3/6,i386] libgcc: Enable hfmode soft-sf/df/xf/tf extensions and truncations. [4/6] Support -fexcess-precision=16 which will enable FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 when backe… [6/6] AVX512FP16: Support vector init/broadcast/set/extract for FP16. [5/6] AVX512FP16: Initial support for AVX512FP16 feature and scalar _Float16 instructions.

diff --git a/gcc/ada/gcc-interface/misc.c b/gcc/ada/gcc-interface/misc.c index 186367ac6d1..96199bd4b63 100644 --- a/gcc/ada/gcc-interface/misc.c +++ b/gcc/ada/gcc-interface/misc.c @@ -256,6 +256,9 @@ gnat_post_options (const char **pfilename ATTRIBUTE_UNUSED) /* Excess precision other than "fast" requires front-end support. */ if (flag_excess_precision == EXCESS_PRECISION_STANDARD) sorry ("%<-fexcess-precision=standard%> for Ada"); + else if (flag_excess_precision == EXCESS_PRECISION_FLOAT16) + sorry ("%<-fexcess-precision=16%> for Ada"); + flag_excess_precision = EXCESS_PRECISION_FAST; /* No psABI change warnings for Ada. */ diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index aacdfb46a02..7e72062c77c 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -8772,7 +8772,7 @@ excess_precision_mode_join (enum flt_eval_method x, This relates to the effective excess precision seen by the user, which is the join point of the precision the target requests for - -fexcess-precision={standard,fast} and the implicit excess precision + -fexcess-precision={standard,fast,16} and the implicit excess precision the target uses. */ static enum flt_eval_method @@ -8784,7 +8784,9 @@ c_ts18661_flt_eval_method (void) enum excess_precision_type flag_type = (flag_excess_precision == EXCESS_PRECISION_STANDARD ? EXCESS_PRECISION_TYPE_STANDARD - : EXCESS_PRECISION_TYPE_FAST); + : (flag_excess_precision == EXCESS_PRECISION_FLOAT16 + ? EXCESS_PRECISION_TYPE_FLOAT16 + : EXCESS_PRECISION_TYPE_FAST)); enum flt_eval_method requested = targetm.c.excess_precision (flag_type); diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c index f79f939bd10..5f30354a33c 100644 --- a/gcc/c-family/c-cppbuiltin.c +++ b/gcc/c-family/c-cppbuiltin.c @@ -753,7 +753,7 @@ cpp_atomic_builtins (cpp_reader *pfile) /* Return TRUE if the implicit excess precision in which the back-end will compute floating-point calculations is not more than the explicit excess precision that the front-end will apply under - -fexcess-precision=[standard|fast]. + -fexcess-precision=[standard|fast|16]. More intuitively, return TRUE if the excess precision proposed by the front-end is the excess precision that will actually be used. */ @@ -764,7 +764,9 @@ c_cpp_flt_eval_method_iec_559 (void) enum excess_precision_type front_end_ept = (flag_excess_precision == EXCESS_PRECISION_STANDARD ? EXCESS_PRECISION_TYPE_STANDARD - : EXCESS_PRECISION_TYPE_FAST); + : (flag_excess_precision == EXCESS_PRECISION_FLOAT16 + ? EXCESS_PRECISION_TYPE_FLOAT16 + : EXCESS_PRECISION_TYPE_FAST)); enum flt_eval_method back_end = targetm.c.excess_precision (EXCESS_PRECISION_TYPE_IMPLICIT); diff --git a/gcc/common.opt b/gcc/common.opt index d9da1131eda..3dd74766400 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -1518,7 +1518,7 @@ Perform a number of minor, expensive optimizations. fexcess-precision= Common Joined RejectNegative Enum(excess_precision) Var(flag_excess_precision) Init(EXCESS_PRECISION_DEFAULT) Optimization SetByCombined --fexcess-precision=[fast|standard] Specify handling of excess floating-point precision. +-fexcess-precision=[fast|standard|16] Specify handling of excess floating-point precision. Enum Name(excess_precision) Type(enum excess_precision) UnknownError(unknown excess precision style %qs) @@ -1529,6 +1529,9 @@ Enum(excess_precision) String(fast) Value(EXCESS_PRECISION_FAST) EnumValue Enum(excess_precision) String(standard) Value(EXCESS_PRECISION_STANDARD) +EnumValue +Enum(excess_precision) String(16) Value(EXCESS_PRECISION_FLOAT16) + ; Whether we permit the extended set of values for FLT_EVAL_METHOD ; introduced in ISO/IEC TS 18661-3, or limit ourselves to those in C99/C11. fpermitted-flt-eval-methods= diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index 3bdf19d71b5..c986a93a243 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -24797,6 +24797,7 @@ aarch64_excess_precision (enum excess_precision_type type) ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 : FLT_EVAL_METHOD_PROMOTE_TO_FLOAT); case EXCESS_PRECISION_TYPE_IMPLICIT: + case EXCESS_PRECISION_TYPE_FLOAT16: return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16; default: gcc_unreachable (); diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 6d781e23ee9..e2a18615860 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -25599,6 +25599,7 @@ arm_excess_precision (enum excess_precision_type type) ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 : FLT_EVAL_METHOD_PROMOTE_TO_FLOAT); case EXCESS_PRECISION_TYPE_IMPLICIT: + case EXCESS_PRECISION_TYPE_FLOAT16: return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16; default: gcc_unreachable (); diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 7979e240426..dc673c89bc8 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -23352,6 +23352,8 @@ ix86_get_excess_precision (enum excess_precision_type type) return (type == EXCESS_PRECISION_TYPE_STANDARD ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT : FLT_EVAL_METHOD_UNPREDICTABLE); + case EXCESS_PRECISION_TYPE_FLOAT16: + return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16; default: gcc_unreachable (); } diff --git a/gcc/config/m68k/m68k.c b/gcc/config/m68k/m68k.c index 3f63c60fa92..2fef457c09e 100644 --- a/gcc/config/m68k/m68k.c +++ b/gcc/config/m68k/m68k.c @@ -7115,6 +7115,8 @@ m68k_excess_precision (enum excess_precision_type type) return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT; return FLT_EVAL_METHOD_PROMOTE_TO_LONG_DOUBLE; + case EXCESS_PRECISION_TYPE_FLOAT16: + error ("%<-fexcess-precision=16%> is not supported on this target"); default: gcc_unreachable (); } diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c index b1d3b99784d..234ee4ac9c4 100644 --- a/gcc/config/s390/s390.c +++ b/gcc/config/s390/s390.c @@ -16515,6 +16515,8 @@ s390_excess_precision (enum excess_precision_type type) ensure consistency with the implementation in glibc, report that float is evaluated to the range and precision of double. */ return FLT_EVAL_METHOD_PROMOTE_TO_DOUBLE; + case EXCESS_PRECISION_TYPE_FLOAT16: + error ("%<-fexcess-precision=16%> is not supported on this target"); default: gcc_unreachable (); } diff --git a/gcc/coretypes.h b/gcc/coretypes.h index 406572e947d..07b9aa656c5 100644 --- a/gcc/coretypes.h +++ b/gcc/coretypes.h @@ -424,7 +424,8 @@ enum excess_precision_type { EXCESS_PRECISION_TYPE_IMPLICIT, EXCESS_PRECISION_TYPE_STANDARD, - EXCESS_PRECISION_TYPE_FAST + EXCESS_PRECISION_TYPE_FAST, + EXCESS_PRECISION_TYPE_FLOAT16 }; /* Level of size optimization. */ diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index f42fd633725..3a1978efc97 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -1161,7 +1161,8 @@ operations will be emulated by software emulation and the @code{float} instructions. The default behavior for @code{FLT_EVAL_METHOD} is to keep the intermediate result of the operation as 32-bit precision. This may lead to inconsistent behavior between software emulation and AVX512-FP16 -instructions. +instructions. Using @option{-fexcess-precision=16} and will force round +back after each operation. @node Decimal Float @section Decimal Floating Types diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index c8f4abe3e41..9fac173a217 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -982,20 +982,26 @@ Do not define this macro if it would never modify @var{m}. Return a value, with the same meaning as the C99 macro @code{FLT_EVAL_METHOD} that describes which excess precision should be applied. @var{type} is either @code{EXCESS_PRECISION_TYPE_IMPLICIT}, -@code{EXCESS_PRECISION_TYPE_FAST}, or -@code{EXCESS_PRECISION_TYPE_STANDARD}. For +@code{EXCESS_PRECISION_TYPE_FAST}, +@code{EXCESS_PRECISION_TYPE_STANDARD}, or +@code{EXCESS_PRECISION_TYPE_FLOAT16}. For @code{EXCESS_PRECISION_TYPE_IMPLICIT}, the target should return which precision and range operations will be implictly evaluated in regardless of the excess precision explicitly added. For -@code{EXCESS_PRECISION_TYPE_STANDARD} and +@code{EXCESS_PRECISION_TYPE_STANDARD}, +@code{EXCESS_PRECISION_TYPE_FLOAT16}, and @code{EXCESS_PRECISION_TYPE_FAST}, the target should return the explicit excess precision that should be added depending on the value set for @option{-fexcess-precision=@r{[}standard@r{|}fast@r{]}}. Note that unpredictable explicit excess precision does not make sense, so a target should never return @code{FLT_EVAL_METHOD_UNPREDICTABLE} -when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD} or +when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD}, +@code{EXCESS_PRECISION_TYPE_FLOAT16} or @code{EXCESS_PRECISION_TYPE_FAST}. @end deftypefn +Return a value, with the same meaning as the C99 macro +@code{FLT_EVAL_METHOD} that describes which excess precision should be +applied. @deftypefn {Target Hook} machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree @var{type}, machine_mode @var{mode}, int *@var{punsignedp}, const_tree @var{funtype}, int @var{for_return}) Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in index 9c4b5016053..90a8d790758 100644 --- a/gcc/doc/tm.texi.in +++ b/gcc/doc/tm.texi.in @@ -929,6 +929,9 @@ Do not define this macro if it would never modify @var{m}. @end defmac @hook TARGET_C_EXCESS_PRECISION +Return a value, with the same meaning as the C99 macro +@code{FLT_EVAL_METHOD} that describes which excess precision should be +applied. @hook TARGET_PROMOTE_FUNCTION_MODE diff --git a/gcc/flag-types.h b/gcc/flag-types.h index e43d1de490d..5eeb5046222 100644 --- a/gcc/flag-types.h +++ b/gcc/flag-types.h @@ -198,7 +198,8 @@ enum excess_precision { EXCESS_PRECISION_DEFAULT, EXCESS_PRECISION_FAST, - EXCESS_PRECISION_STANDARD + EXCESS_PRECISION_STANDARD, + EXCESS_PRECISION_FLOAT16 }; /* The options for which values of FLT_EVAL_METHOD are permissible. */ diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c index 1723f689a57..847e20e8829 100644 --- a/gcc/fortran/options.c +++ b/gcc/fortran/options.c @@ -267,6 +267,9 @@ gfc_post_options (const char **pfilename) support. */ if (flag_excess_precision == EXCESS_PRECISION_STANDARD) sorry ("%<-fexcess-precision=standard%> for Fortran"); + else if (flag_excess_precision == EXCESS_PRECISION_FLOAT16) + sorry ("%<-fexcess-precision=16%> for Fortran"); + flag_excess_precision = EXCESS_PRECISION_FAST; /* Fortran allows associative math - but we cannot reassociate if diff --git a/gcc/target.def b/gcc/target.def index 2e40448e6c5..b0bd79a0671 100644 --- a/gcc/target.def +++ b/gcc/target.def @@ -6192,18 +6192,21 @@ DEFHOOK "Return a value, with the same meaning as the C99 macro\n\ @code{FLT_EVAL_METHOD} that describes which excess precision should be\n\ applied. @var{type} is either @code{EXCESS_PRECISION_TYPE_IMPLICIT},\n\ -@code{EXCESS_PRECISION_TYPE_FAST}, or\n\ -@code{EXCESS_PRECISION_TYPE_STANDARD}. For\n\ +@code{EXCESS_PRECISION_TYPE_FAST},\n\ +@code{EXCESS_PRECISION_TYPE_STANDARD}, or\n\ +@code{EXCESS_PRECISION_TYPE_FLOAT16}. For\n\ @code{EXCESS_PRECISION_TYPE_IMPLICIT}, the target should return which\n\ precision and range operations will be implictly evaluated in regardless\n\ of the excess precision explicitly added. For\n\ -@code{EXCESS_PRECISION_TYPE_STANDARD} and\n\ +@code{EXCESS_PRECISION_TYPE_STANDARD}, \n\ +@code{EXCESS_PRECISION_TYPE_FLOAT16}, and\n\ @code{EXCESS_PRECISION_TYPE_FAST}, the target should return the\n\ explicit excess precision that should be added depending on the\n\ value set for @option{-fexcess-precision=@r{[}standard@r{|}fast@r{]}}.\n\ Note that unpredictable explicit excess precision does not make sense,\n\ so a target should never return @code{FLT_EVAL_METHOD_UNPREDICTABLE}\n\ -when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD} or\n\ +when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD},\n\ +@code{EXCESS_PRECISION_TYPE_FLOAT16} or\n\ @code{EXCESS_PRECISION_TYPE_FAST}.", enum flt_eval_method, (enum excess_precision_type type), default_excess_precision) diff --git a/gcc/testsuite/gcc.target/i386/float16-6.c b/gcc/testsuite/gcc.target/i386/float16-6.c new file mode 100644 index 00000000000..599f4495086 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/float16-6.c @@ -0,0 +1,8 @@ +/* { dg-do compile } */ +/* { dg-options "-msse2 -O2 -fdump-tree-gimple -fexcess-precision=16" } */ +/* { dg-final { scan-tree-dump-not "\\(float\\)" "gimple" } } */ +_Float16 +foo (_Float16 a, _Float16 b, _Float16 c) +{ + return a + b + c; +} diff --git a/gcc/tree.c b/gcc/tree.c index bead1ac134c..20dfbe00b88 100644 --- a/gcc/tree.c +++ b/gcc/tree.c @@ -7633,7 +7633,8 @@ excess_precision_type (tree type) enum excess_precision_type requested_type = (flag_excess_precision == EXCESS_PRECISION_FAST ? EXCESS_PRECISION_TYPE_FAST - : EXCESS_PRECISION_TYPE_STANDARD); + : (flag_excess_precision == EXCESS_PRECISION_FLOAT16 + ? EXCESS_PRECISION_TYPE_FLOAT16 :EXCESS_PRECISION_TYPE_STANDARD)); enum flt_eval_method target_flt_eval_method = targetm.c.excess_precision (requested_type);

[4/6] Support -fexcess-precision=16 which will enable FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16 when backend supports _Float16.

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