- Generated by
1.8.1.1
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GCC Middle and Back End API Reference
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Data Structures | |
| struct | return_statements_t |
| struct | lower_data |
Typedefs | |
| typedef struct return_statements_t | return_statements_t |
Functions | |
| static void | lower_stmt (gimple_stmt_iterator *, struct lower_data *) |
| static void | lower_gimple_bind (gimple_stmt_iterator *, struct lower_data *) |
| static void | lower_try_catch (gimple_stmt_iterator *, struct lower_data *) |
| static void | lower_gimple_return (gimple_stmt_iterator *, struct lower_data *) |
| static void | lower_builtin_setjmp (gimple_stmt_iterator *) |
| static unsigned int | lower_function_body () |
| gimple_opt_pass * | make_pass_lower_cf () |
| static void | lower_sequence () |
| static void | lower_omp_directive () |
| static void | lower_stmt () |
| static void | lower_gimple_bind () |
| static void | lower_try_catch () |
| static bool | gimple_try_catch_may_fallthru () |
| bool | gimple_stmt_may_fallthru () |
| bool | gimple_seq_may_fallthru () |
| static void | lower_gimple_return () |
| static void | lower_builtin_setjmp () |
| void | record_vars_into () |
| void | record_vars () |
| typedef struct return_statements_t return_statements_t |
| bool gimple_seq_may_fallthru | ( | ) |
Same as gimple_stmt_may_fallthru, but for the gimple sequence SEQ.
| bool gimple_stmt_may_fallthru | ( | ) |
Try to determine if we can continue executing the statement immediately following STMT. This guess need not be 100% accurate; simply be conservative and return true if we don't know. This is used only to avoid stupidly generating extra code. If we're wrong, we'll just delete the extra code later.
Easy cases. If the last statement of the seq implies
control transfer, then we can't fall through. Switch has already been lowered and represents a branch
to a selected label and hence can't fall through. GIMPLE_COND's are already lowered into a two-way branch. They
can't fall through. It must be a GIMPLE_TRY_FINALLY.
The finally clause is always executed after the try clause,
so if it does not fall through, then the try-finally will not
fall through. Otherwise, if the try clause does not fall
through, then when the finally clause falls through it will
resume execution wherever the try clause was going. So the
whole try-finally will only fall through if both the try
clause and the finally clause fall through. Functions that do not return do not fall through.
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Try to determine whether a TRY_CATCH expression can fall through. This is a subroutine of gimple_stmt_may_fallthru.
We don't handle GIMPLE_TRY_FINALLY.
If the TRY block can fall through, the whole TRY_CATCH can
fall through. We expect to see a sequence of GIMPLE_CATCH stmts, each with a
catch expression and a body. The whole try/catch may fall
through iff any of the catch bodies falls through. The exception filter expression only matters if there is an
exception. If the exception does not match EH_FILTER_TYPES,
we will execute EH_FILTER_FAILURE, and we will fall through
if that falls through. If the exception does match
EH_FILTER_TYPES, the stack unwinder will continue up the
stack, so we will not fall through. We don't know whether we
will throw an exception which matches EH_FILTER_TYPES or not,
so we just ignore EH_FILTER_TYPES and assume that we might
throw an exception which doesn't match. This case represents statements to be executed when an
exception occurs. Those statements are implicitly followed
by a GIMPLE_RESX to resume execution after the exception. So
in this case the try/catch never falls through.
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Lower a __builtin_setjmp GSI.
__builtin_setjmp is passed a pointer to an array of five words (not
all will be used on all machines). It operates similarly to the C
library function of the same name, but is more efficient.
It is lowered into 3 other builtins, namely __builtin_setjmp_setup,
__builtin_setjmp_dispatcher and __builtin_setjmp_receiver, but with
__builtin_setjmp_dispatcher shared among all the instances; that's
why it is only emitted at the end by lower_function_body.
After full lowering, the body of the function should look like:
{
void * setjmpvar.0;
int D.1844;
int D.2844;
[...]
__builtin_setjmp_setup (&buf, &<D1847>);
D.1844 = 0;
goto <D1846>;
<D1847>:;
__builtin_setjmp_receiver (&<D1847>);
D.1844 = 1;
<D1846>:;
if (D.1844 == 0) goto <D1848>; else goto <D1849>;
[...]
__builtin_setjmp_setup (&buf, &<D2847>);
D.2844 = 0;
goto <D2846>;
<D2847>:;
__builtin_setjmp_receiver (&<D2847>);
D.2844 = 1;
<D2846>:;
if (D.2844 == 0) goto <D2848>; else goto <D2849>;
[...]
<D3850>:;
return;
<D3853>: [non-local];
setjmpvar.0 = __builtin_setjmp_dispatcher (&<D3853>);
goto setjmpvar.0;
}
The dispatcher block will be both the unique destination of all the
abnormal call edges and the unique source of all the abnormal edges
to the receivers, thus keeping the complexity explosion localized. NEXT_LABEL is the label __builtin_longjmp will jump to. Its address is
passed to both __builtin_setjmp_setup and __builtin_setjmp_receiver. Build '__builtin_setjmp_setup (BUF, NEXT_LABEL)' and insert.
Build 'DEST = 0' and insert.
Build 'goto CONT_LABEL' and insert.
Build 'NEXT_LABEL:' and insert.
Build '__builtin_setjmp_receiver (NEXT_LABEL)' and insert.
Build 'DEST = 1' and insert.
Build 'CONT_LABEL:' and insert.
Remove the call to __builtin_setjmp.
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static |
Lower the body of current_function_decl from High GIMPLE into Low GIMPLE.
The gimplifier should've left a body of exactly one statement,
namely a GIMPLE_BIND. If the function falls off the end, we need a null return statement.
If we've already got one in the return_statements vector, we don't
need to do anything special. Otherwise build one by hand. If we lowered any return statements, emit the representative
at the end of the function. If the function calls __builtin_setjmp, we need to emit the computed
goto that will serve as the unique dispatcher for all the receivers. Build 'DISP_LABEL:' and insert.
This mark will create forward edges from every call site.
Build 'DISP_VAR = __builtin_setjmp_dispatcher (DISP_LABEL);'
and insert. Build 'goto DISP_VAR;' and insert.
Once the old body has been lowered, replace it with the new
lowered sequence.
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Referenced by lower_omp_directive().
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Lower a bind_expr TSI. DATA is passed through the recursion.
The outermost block of the original function may not be the
outermost statement chain of the gimplified function. So we
may see the outermost block just inside the function. We do not expect to handle duplicate blocks.
Block tree may get clobbered by inlining. Normally this would
be fixed in rest_of_decl_compilation using block notes, but
since we are not going to emit them, it is up to us. The GIMPLE_BIND no longer carries any useful information -- kill it.
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Lower a GIMPLE_RETURN GSI. DATA is passed through the recursion.
Match this up with an existing return statement that's been created.
Remove the line number from the representative return statement.
It now fills in for many such returns. Failure to remove this
will result in incorrect results for coverage analysis. Not found. Create a new label and record the return statement.
Generate a goto statement and remove the return statement.
When not optimizing, make sure user returns are preserved.
References build_addr(), build_zero_cst(), builtin_decl_implicit(), create_artificial_label(), current_function_decl, fold_convert_loc(), g, gimple_block(), gimple_build_call(), gimple_build_goto(), gimple_build_label(), gimple_call_arg(), gimple_call_lhs(), gimple_location(), gimple_set_block(), gimple_set_location(), gsi_insert_before(), GSI_SAME_STMT, and gsi_stmt().
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Lower the OpenMP directive statement pointed by GSI. DATA is passed through the recursion.
References lower_data::block, lower_data::cannot_fallthru, gimple_set_block(), gsi_next(), gsi_stmt(), and lower_gimple_bind().
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Lower sequence SEQ. Unlike gimplification the statements are not relowered when they are changed -- if this has to be done, the lowering routine must do it explicitly. DATA is passed through the recursion.
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Lower statement GSI. DATA is passed through the recursion. We try to track the fallthruness of statements and get rid of unreachable return statements in order to prevent the EH lowering pass from adding useless edges that can cause bogus warnings to be issued later; this guess need not be 100% accurate, simply be conservative and reset cannot_fallthru to false if we don't know.
Propagate fallthruness.
Propagate fallthruness.
It must be a GIMPLE_TRY_FINALLY.
The finally clause is always executed after the try clause,
so if it does not fall through, then the try-finally will not
fall through. Otherwise, if the try clause does not fall
through, then when the finally clause falls through it will
resume execution wherever the try clause was going. So the
whole try-finally will only fall through if both the try
clause and the finally clause fall through.
References gsi_remove().
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Same as above, but for a GIMPLE_TRY_CATCH.
We don't handle GIMPLE_TRY_FINALLY.
We expect to see a sequence of GIMPLE_CATCH stmts, each with a
catch expression and a body. The whole try/catch may fall
through iff any of the catch bodies falls through. The exception filter expression only matters if there is an
exception. If the exception does not match EH_FILTER_TYPES,
we will execute EH_FILTER_FAILURE, and we will fall through
if that falls through. If the exception does match
EH_FILTER_TYPES, the stack unwinder will continue up the
stack, so we will not fall through. We don't know whether we
will throw an exception which matches EH_FILTER_TYPES or not,
so we just ignore EH_FILTER_TYPES and assume that we might
throw an exception which doesn't match. This case represents statements to be executed when an
exception occurs. Those statements are implicitly followed
by a GIMPLE_RESX to resume execution after the exception. So
in this case the try/catch never falls through.
| gimple_opt_pass* make_pass_lower_cf | ( | ) |
References gsi_stmt().
| void record_vars | ( | ) |
Record the variables in VARS into current_function_decl.
| void record_vars_into | ( | ) |
Record the variables in VARS into function FN.
BIND_EXPRs contains also function/type/constant declarations
we don't need to care about. Nothing to do in this case.
Record the variable.
1.8.1.1