mirror of git://gcc.gnu.org/git/gcc.git
re PR c/68908 (inefficient code for _Atomic operations)
PR c/68908 * c-typeck.c (build_atomic_assign): Improve commentary. Add optimization to use __atomic_fetch_* built-in if possible. * gcc.dg/atomic/c11-atomic-exec-6.c: New test. * gcc.dg/atomic/c11-atomic-exec-7.c: New test. * gcc.dg/atomic/stdatomic-op-5.c: New test. From-SVN: r232052
This commit is contained in:
Marek Polacek
Marek Polacek
parent
8db883aa82
commit
2fe0a2080e
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@ -1,3 +1,9 @@
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2016-01-04 Marek Polacek <polacek@redhat.com>
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PR c/68908
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* c-typeck.c (build_atomic_assign): Improve commentary. Add
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optimization to use __atomic_fetch_* built-in if possible.
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2015-12-23 Thomas Schwinge <thomas@codesourcery.com>
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2015-12-23 Thomas Schwinge <thomas@codesourcery.com>
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* c-parser.c (c_parser_oacc_clause_use_device): Merge function
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* c-parser.c (c_parser_oacc_clause_use_device): Merge function
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116
gcc/c/c-typeck.c
116
gcc/c/c-typeck.c
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@ -3698,9 +3698,9 @@ pointer_diff (location_t loc, tree op0, tree op1)
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return convert (restype, result);
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return convert (restype, result);
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}
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}
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/* Expand atomic compound assignments into an approriate sequence as
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/* Expand atomic compound assignments into an appropriate sequence as
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specified by the C11 standard section 6.5.16.2.
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specified by the C11 standard section 6.5.16.2.
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given
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_Atomic T1 E1
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_Atomic T1 E1
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T2 E2
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T2 E2
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E1 op= E2
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E1 op= E2
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@ -3732,26 +3732,25 @@ loop:
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done:
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done:
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feupdateenv (&fenv);
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feupdateenv (&fenv);
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Also note that the compiler is simply issuing the generic form of
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The compiler will issue the __atomic_fetch_* built-in when possible,
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the atomic operations. This requires temp(s) and has their address
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otherwise it will generate the generic form of the atomic operations.
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taken. The atomic processing is smart enough to figure out when the
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This requires temp(s) and has their address taken. The atomic processing
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size of an object can utilize a lock-free version, and convert the
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is smart enough to figure out when the size of an object can utilize
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built-in call to the appropriate lock-free routine. The optimizers
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a lock-free version, and convert the built-in call to the appropriate
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will then dispose of any temps that are no longer required, and
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lock-free routine. The optimizers will then dispose of any temps that
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lock-free implementations are utilized as long as there is target
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are no longer required, and lock-free implementations are utilized as
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support for the required size.
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long as there is target support for the required size.
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If the operator is NOP_EXPR, then this is a simple assignment, and
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If the operator is NOP_EXPR, then this is a simple assignment, and
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an __atomic_store is issued to perform the assignment rather than
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an __atomic_store is issued to perform the assignment rather than
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the above loop.
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the above loop. */
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*/
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/* Build an atomic assignment at LOC, expanding into the proper
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/* Build an atomic assignment at LOC, expanding into the proper
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sequence to store LHS MODIFYCODE= RHS. Return a value representing
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sequence to store LHS MODIFYCODE= RHS. Return a value representing
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the result of the operation, unless RETURN_OLD_P in which case
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the result of the operation, unless RETURN_OLD_P, in which case
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return the old value of LHS (this is only for postincrement and
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return the old value of LHS (this is only for postincrement and
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postdecrement). */
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postdecrement). */
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static tree
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static tree
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build_atomic_assign (location_t loc, tree lhs, enum tree_code modifycode,
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build_atomic_assign (location_t loc, tree lhs, enum tree_code modifycode,
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tree rhs, bool return_old_p)
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tree rhs, bool return_old_p)
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@ -3818,6 +3817,93 @@ build_atomic_assign (location_t loc, tree lhs, enum tree_code modifycode,
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return build2 (COMPOUND_EXPR, nonatomic_lhs_type, compound_stmt, val);
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return build2 (COMPOUND_EXPR, nonatomic_lhs_type, compound_stmt, val);
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}
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}
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/* Attempt to implement the atomic operation as an __atomic_fetch_* or
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__atomic_*_fetch built-in rather than a CAS loop. atomic_bool type
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isn't applicable for such builtins. ??? Do we want to handle enums? */
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if ((TREE_CODE (lhs_type) == INTEGER_TYPE || POINTER_TYPE_P (lhs_type))
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&& TREE_CODE (rhs_type) == INTEGER_TYPE)
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{
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built_in_function fncode;
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switch (modifycode)
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{
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case PLUS_EXPR:
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case POINTER_PLUS_EXPR:
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fncode = (return_old_p
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? BUILT_IN_ATOMIC_FETCH_ADD_N
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: BUILT_IN_ATOMIC_ADD_FETCH_N);
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break;
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case MINUS_EXPR:
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fncode = (return_old_p
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? BUILT_IN_ATOMIC_FETCH_SUB_N
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: BUILT_IN_ATOMIC_SUB_FETCH_N);
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break;
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case BIT_AND_EXPR:
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fncode = (return_old_p
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? BUILT_IN_ATOMIC_FETCH_AND_N
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: BUILT_IN_ATOMIC_AND_FETCH_N);
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break;
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case BIT_IOR_EXPR:
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fncode = (return_old_p
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? BUILT_IN_ATOMIC_FETCH_OR_N
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: BUILT_IN_ATOMIC_OR_FETCH_N);
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break;
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case BIT_XOR_EXPR:
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fncode = (return_old_p
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? BUILT_IN_ATOMIC_FETCH_XOR_N
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: BUILT_IN_ATOMIC_XOR_FETCH_N);
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break;
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default:
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goto cas_loop;
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}
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/* We can only use "_1" through "_16" variants of the atomic fetch
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built-ins. */
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unsigned HOST_WIDE_INT size = tree_to_uhwi (TYPE_SIZE_UNIT (lhs_type));
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if (size != 1 && size != 2 && size != 4 && size != 8 && size != 16)
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goto cas_loop;
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/* If this is a pointer type, we need to multiply by the size of
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the pointer target type. */
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if (POINTER_TYPE_P (lhs_type))
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{
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if (!COMPLETE_TYPE_P (TREE_TYPE (lhs_type))
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/* ??? This would introduce -Wdiscarded-qualifiers
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warning: __atomic_fetch_* expect volatile void *
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type as the first argument. (Assignments between
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atomic and non-atomic objects are OK.) */
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|| TYPE_RESTRICT (lhs_type))
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goto cas_loop;
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tree sz = TYPE_SIZE_UNIT (TREE_TYPE (lhs_type));
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rhs = fold_build2_loc (loc, MULT_EXPR, ptrdiff_type_node,
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convert (ptrdiff_type_node, rhs),
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convert (ptrdiff_type_node, sz));
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}
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/* Build __atomic_fetch_* (&lhs, &val, SEQ_CST), or
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__atomic_*_fetch (&lhs, &val, SEQ_CST). */
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fndecl = builtin_decl_explicit (fncode);
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params->quick_push (lhs_addr);
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params->quick_push (rhs);
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params->quick_push (seq_cst);
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func_call = c_build_function_call_vec (loc, vNULL, fndecl, params, NULL);
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newval = create_tmp_var_raw (nonatomic_lhs_type);
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TREE_ADDRESSABLE (newval) = 1;
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TREE_NO_WARNING (newval) = 1;
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rhs = build4 (TARGET_EXPR, nonatomic_lhs_type, newval, func_call,
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NULL_TREE, NULL_TREE);
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SET_EXPR_LOCATION (rhs, loc);
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add_stmt (rhs);
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/* Finish the compound statement. */
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compound_stmt = c_end_compound_stmt (loc, compound_stmt, false);
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/* NEWVAL is the value which was stored, return a COMPOUND_STMT of
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the statement and that value. */
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return build2 (COMPOUND_EXPR, nonatomic_lhs_type, compound_stmt, newval);
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}
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cas_loop:
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/* Create the variables and labels required for the op= form. */
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/* Create the variables and labels required for the op= form. */
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old = create_tmp_var_raw (nonatomic_lhs_type);
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old = create_tmp_var_raw (nonatomic_lhs_type);
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old_addr = build_unary_op (loc, ADDR_EXPR, old, 0);
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old_addr = build_unary_op (loc, ADDR_EXPR, old, 0);
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@ -1,3 +1,10 @@
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2016-01-04 Marek Polacek <polacek@redhat.com>
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PR c/68908
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* gcc.dg/atomic/c11-atomic-exec-6.c: New test.
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* gcc.dg/atomic/c11-atomic-exec-7.c: New test.
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* gcc.dg/atomic/stdatomic-op-5.c: New test.
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2016-01-04 Eric Botcazou <ebotcazou@adacore.com>
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2016-01-04 Eric Botcazou <ebotcazou@adacore.com>
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* gcc.target/sparc/20160104-2.c: New test.
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* gcc.target/sparc/20160104-2.c: New test.
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@ -0,0 +1,54 @@
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/* Test we do correct thing for adding to / subtracting from a pointer,
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i.e. that the multiplication by the size of the pointer target type
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still occurs. */
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/* { dg-do run } */
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/* { dg-options "-std=c11 -pedantic-errors" } */
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#define TEST_POINTER_ADD_SUB(TYPE) \
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do \
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{ \
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TYPE a[3][3]; \
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TYPE (*_Atomic q)[3] = &a[0]; \
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++q; \
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if (q != &a[1]) \
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__builtin_abort (); \
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q++; \
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if (q != &a[2]) \
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__builtin_abort (); \
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--q; \
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if (q != &a[1]) \
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__builtin_abort (); \
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q--; \
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if (q != &a[0]) \
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__builtin_abort (); \
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q += 2; \
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if (q != &a[2]) \
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__builtin_abort (); \
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q -= 2; \
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if (q != &a[0]) \
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__builtin_abort (); \
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} \
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while (0)
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int
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main (void)
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{
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TEST_POINTER_ADD_SUB (_Bool);
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TEST_POINTER_ADD_SUB (char);
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TEST_POINTER_ADD_SUB (signed char);
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TEST_POINTER_ADD_SUB (unsigned char);
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TEST_POINTER_ADD_SUB (signed short);
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TEST_POINTER_ADD_SUB (unsigned short);
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TEST_POINTER_ADD_SUB (signed int);
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TEST_POINTER_ADD_SUB (unsigned int);
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TEST_POINTER_ADD_SUB (signed long);
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TEST_POINTER_ADD_SUB (unsigned long);
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TEST_POINTER_ADD_SUB (signed long long);
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TEST_POINTER_ADD_SUB (unsigned long long);
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TEST_POINTER_ADD_SUB (float);
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TEST_POINTER_ADD_SUB (double);
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TEST_POINTER_ADD_SUB (long double);
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TEST_POINTER_ADD_SUB (_Complex float);
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TEST_POINTER_ADD_SUB (_Complex double);
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TEST_POINTER_ADD_SUB (_Complex long double);
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}
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@ -0,0 +1,34 @@
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/* Test we're able use __atomic_fetch_* where possible and verify
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we generate correct code. */
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/* { dg-do run } */
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/* { dg-options "-std=c11 -pedantic-errors -fdump-tree-original" } */
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#include <stdatomic.h>
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#include <limits.h>
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extern void abort (void);
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#define TEST_TYPE(TYPE, MAX) \
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do \
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{ \
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struct S { char a[(MAX) + 1]; }; \
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TYPE t = 1; \
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struct S a[2][2]; \
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struct S (*_Atomic p)[2] = &a[0]; \
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p += t; \
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if (p != &a[1]) \
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abort (); \
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p -= t; \
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if (p != &a[0]) \
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abort (); \
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} \
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while (0)
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int
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main (void)
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{
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TEST_TYPE (signed char, UCHAR_MAX);
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TEST_TYPE (signed short, USHRT_MAX);
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}
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/* { dg-final { scan-tree-dump-not "__atomic_compare_exchange" "original" } } */
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@ -0,0 +1,141 @@
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/* Test we're able use __atomic_fetch_* where possible and verify
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we generate correct code. */
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/* { dg-do run } */
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/* { dg-options "-std=c11 -pedantic-errors -fdump-tree-original" } */
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#include <stdatomic.h>
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extern void abort (void);
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static void
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test_inc_dec (void)
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{
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atomic_int i = ATOMIC_VAR_INIT (1);
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i++;
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if (i != 2)
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abort ();
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i--;
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if (i != 1)
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abort ();
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++i;
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if (i != 2)
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abort ();
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--i;
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|
if (i != 1)
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|
abort ();
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if (++i != 2)
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abort ();
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if (i++ != 2)
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abort ();
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if (i != 3)
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abort ();
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if (i-- != 3)
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abort ();
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if (i != 2)
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abort ();
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}
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static void
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test_add_sub (void)
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{
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atomic_int i = ATOMIC_VAR_INIT (1);
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|
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i += 2;
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if (i != 3)
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|
abort ();
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i -= 2;
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|
if (i != 1)
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|
abort ();
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|
if ((i += 2) != 3)
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|
abort ();
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|
if ((i -= 2) != 1)
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abort ();
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}
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|
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static void
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test_and (void)
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{
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atomic_int i = ATOMIC_VAR_INIT (5);
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|
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i &= 4;
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if (i != 4)
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abort ();
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if ((i &= 4) != 4)
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abort ();
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}
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|
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static void
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test_xor (void)
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{
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atomic_int i = ATOMIC_VAR_INIT (5);
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i ^= 2;
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if (i != 7)
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abort ();
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if ((i ^= 4) != 3)
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abort ();
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}
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static void
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test_or (void)
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{
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atomic_int i = ATOMIC_VAR_INIT (5);
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|
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i |= 2;
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if (i != 7)
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|
abort ();
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|
if ((i |= 8) != 15)
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|
abort ();
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|
}
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|
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|
static void
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|
test_ptr (atomic_int *p)
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|
{
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|
++*p;
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|
if (*p != 2)
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|
abort ();
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|
|
||||||
|
*p += 2;
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|
if (*p != 4)
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|
abort ();
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|
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||||||
|
(*p)++;
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|
if (*p != 5)
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|
abort ();
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|
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|
--*p;
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||||||
|
if (*p != 4)
|
||||||
|
abort ();
|
||||||
|
|
||||||
|
(*p)--;
|
||||||
|
if (*p != 3)
|
||||||
|
abort ();
|
||||||
|
|
||||||
|
*p -= 2;
|
||||||
|
if (*p != 1)
|
||||||
|
abort ();
|
||||||
|
|
||||||
|
atomic_int j = ATOMIC_VAR_INIT (0);
|
||||||
|
j += *p;
|
||||||
|
if (j != 1)
|
||||||
|
abort ();
|
||||||
|
|
||||||
|
j -= *p;
|
||||||
|
if (j != 0)
|
||||||
|
abort ();
|
||||||
|
}
|
||||||
|
|
||||||
|
int
|
||||||
|
main (void)
|
||||||
|
{
|
||||||
|
atomic_int i = ATOMIC_VAR_INIT (1);
|
||||||
|
test_inc_dec ();
|
||||||
|
test_add_sub ();
|
||||||
|
test_and ();
|
||||||
|
test_xor ();
|
||||||
|
test_or ();
|
||||||
|
test_ptr (&i);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* { dg-final { scan-tree-dump-not "__atomic_compare_exchange" "original" } } */
|
||||||
Loading…
Reference in New Issue