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author | Alexander Monakov <amonakov@ispras.ru> | 2023-05-18 23:47:47 +0300 |
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committer | Alexander Monakov <amonakov@ispras.ru> | 2023-06-21 21:31:25 +0300 |
commit | 1c1dd39625719d92b0ab7afc690f0aada5951072 (patch) | |
tree | c7c2b13aa4ea02235d20473530ccc1457a56346e /gcc | |
parent | 577223aebc7acdd31e62b33c1682fe54a622ae27 (diff) | |
download | gcc-1c1dd39625719d92b0ab7afc690f0aada5951072.zip gcc-1c1dd39625719d92b0ab7afc690f0aada5951072.tar.gz gcc-1c1dd39625719d92b0ab7afc690f0aada5951072.tar.bz2 |
c-family: implement -ffp-contract=on
Implement -ffp-contract=on for C and C++ without changing default
behavior (=off for -std=cNN, =fast for C++ and -std=gnuNN).
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.
Diffstat (limited to 'gcc')
-rw-r--r-- | gcc/c-family/c-gimplify.cc | 79 | ||||
-rw-r--r-- | gcc/common.opt | 3 | ||||
-rw-r--r-- | gcc/config/sh/sh.md | 2 | ||||
-rw-r--r-- | gcc/doc/invoke.texi | 8 | ||||
-rw-r--r-- | gcc/trans-mem.cc | 3 |
5 files changed, 89 insertions, 6 deletions
diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc index ef5c7d9..17b0610 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 +749,75 @@ 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]); + } + /* Avoid gimplify_arg: it emits all side effects into *PRE_P. */ + 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); + return GS_ALL_DONE; + } + break; + } + default:; } diff --git a/gcc/common.opt b/gcc/common.opt index a28ca13..3daec85 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 4622dba..5cb1795 100644 --- a/gcc/config/sh/sh.md +++ b/gcc/config/sh/sh.md @@ -9269,7 +9269,7 @@ (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 215ab0d..8c17a81 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -12077,10 +12077,12 @@ 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 d036e43..9c3d112 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 |