#include "tm.h"
#include "tree.h"
#include "rtl.h"
-#include "varray.h"
#include "gimple.h"
#include "tree-iterator.h"
#include "tree-inline.h"
of the function. */
VEC(return_statements_t,heap) *return_statements;
+ /* True if the current statement cannot fall through. */
+ bool cannot_fallthru;
+
/* True if the function calls __builtin_setjmp. */
bool calls_builtin_setjmp;
};
return 0;
}
-struct gimple_opt_pass pass_lower_cf =
+struct gimple_opt_pass pass_lower_cf =
{
{
GIMPLE_PASS,
lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
{
gimple stmt;
-
+
stmt = gsi_stmt (*gsi);
lower_sequence (gimple_omp_body (stmt), data);
}
-/* Lower statement GSI. DATA is passed through the recursion. */
+/* 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. */
static void
lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
{
case GIMPLE_BIND:
lower_gimple_bind (gsi, data);
+ /* Propagate fallthruness. */
return;
case GIMPLE_COND:
- /* The gimplifier has already lowered this into gotos. */
- break;
+ case GIMPLE_GOTO:
+ case GIMPLE_SWITCH:
+ data->cannot_fallthru = true;
+ gsi_next (gsi);
+ return;
case GIMPLE_RETURN:
- lower_gimple_return (gsi, data);
+ if (data->cannot_fallthru)
+ {
+ gsi_remove (gsi, false);
+ /* Propagate fallthruness. */
+ }
+ else
+ {
+ lower_gimple_return (gsi, data);
+ data->cannot_fallthru = true;
+ }
return;
case GIMPLE_TRY:
- lower_sequence (gimple_try_eval (stmt), data);
- lower_sequence (gimple_try_cleanup (stmt), data);
+ {
+ bool try_cannot_fallthru;
+ lower_sequence (gimple_try_eval (stmt), data);
+ try_cannot_fallthru = data->cannot_fallthru;
+ data->cannot_fallthru = false;
+ lower_sequence (gimple_try_cleanup (stmt), data);
+ /* See gimple_stmt_may_fallthru for the rationale. */
+ if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
+ {
+ data->cannot_fallthru |= try_cannot_fallthru;
+ gsi_next (gsi);
+ return;
+ }
+ }
break;
case GIMPLE_CATCH:
+ data->cannot_fallthru = false;
lower_sequence (gimple_catch_handler (stmt), data);
break;
case GIMPLE_EH_FILTER:
+ data->cannot_fallthru = false;
lower_sequence (gimple_eh_filter_failure (stmt), data);
break;
case GIMPLE_NOP:
case GIMPLE_ASM:
case GIMPLE_ASSIGN:
- case GIMPLE_GOTO:
case GIMPLE_PREDICT:
case GIMPLE_LABEL:
- case GIMPLE_SWITCH:
case GIMPLE_EH_MUST_NOT_THROW:
case GIMPLE_OMP_FOR:
case GIMPLE_OMP_SECTIONS:
&& DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
&& DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
{
- data->calls_builtin_setjmp = true;
lower_builtin_setjmp (gsi);
+ data->cannot_fallthru = false;
+ data->calls_builtin_setjmp = true;
return;
}
- /* After a noreturn call, remove a subsequent GOTO or RETURN that might
- have been mechanically added; this will prevent the EH lowering pass
- from adding useless edges and thus complicating the initial CFG. */
if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
{
+ data->cannot_fallthru = true;
gsi_next (gsi);
- if (!gsi_end_p (*gsi)
- && (gimple_code (gsi_stmt (*gsi)) == GIMPLE_GOTO
- || gimple_code (gsi_stmt (*gsi)) == GIMPLE_RETURN))
- gsi_remove (gsi, false);
return;
}
}
case GIMPLE_OMP_PARALLEL:
case GIMPLE_OMP_TASK:
+ data->cannot_fallthru = false;
lower_omp_directive (gsi, data);
+ data->cannot_fallthru = false;
return;
default:
gcc_unreachable ();
}
+ data->cannot_fallthru = false;
gsi_next (gsi);
}
{
case GOTO_EXPR:
case RETURN_EXPR:
- /* Easy cases. If the last statement of the block implies
+ /* Easy cases. If the last statement of the block implies
control transfer, then we can't fall through. */
return false;
case CALL_EXPR:
/* Functions that do not return do not fall through. */
return (call_expr_flags (stmt) & ECF_NORETURN) == 0;
-
+
case CLEANUP_POINT_EXPR:
return block_may_fallthru (TREE_OPERAND (stmt, 0));
case GIMPLE_GOTO:
case GIMPLE_RETURN:
case GIMPLE_RESX:
- /* Easy cases. If the last statement of the seq implies
+ /* Easy cases. If the last statement of the seq implies
control transfer, then we can't fall through. */
return false;
case GIMPLE_SWITCH:
- /* Switch has already been lowered and represents a
- branch to a selected label and hence can not fall through. */
- return true;
+ /* Switch has already been lowered and represents a branch
+ to a selected label and hence can't fall through. */
+ return false;
case GIMPLE_COND:
/* GIMPLE_COND's are already lowered into a two-way branch. They
return (gimple_seq_may_fallthru (gimple_try_eval (stmt))
&& gimple_seq_may_fallthru (gimple_try_cleanup (stmt)));
- case GIMPLE_ASSIGN:
- return true;
-
case GIMPLE_CALL:
/* Functions that do not return do not fall through. */
return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
-
+
default:
return true;
}
gsi_remove (gsi, false);
}
-/* Lower a __builtin_setjmp TSI.
+/* 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
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