gimple-low.c (struct lower_data): Add cannot_fallthru field.
* gimple-low.c (struct lower_data): Add cannot_fallthru field. (lower_stmt) <GIMPLE_BIND>: Add comment. <GIMPLE_COND, GIMPLE_GOTO, GIMPLE_SWITCH>: Set cannot_fallthru to true and return. <GIMPLE_RETURN>: Remove the statement if cannot_fallthru is set. Otherwise lower it and set cannot_fallthru to true. <GIMPLE_TRY>: Update cannot_fallthru for GIMPLE_TRY_FINALLY and return. <GIMPLE_CATCH, GIMPLE_EH_FILTER>; Set cannot_fallthru to false. <GIMPLE_CALL>: Set cannot_fallthru to false for BUILT_IN_SETJMP and to true for a noreturn call. Do not remove statements. <GIMPLE_OMP_PARALLEL, GIMPLE_OMP_TASK>: Set cannot_fallthru to false. Set cannot_fallthru to false on function exit. (gimple_stmt_may_fallthru) <GIMPLE_SWITCH>: Really return false. <GIMPLE_ASSIGN>: Remove. From-SVN: r152984
This commit is contained in:
Eric Botcazou
Eric Botcazou
parent
585ba38fd5
commit
a141816c42
@ -1,3 +1,20 @@
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2009-10-19 Eric Botcazou <ebotcazou@adacore.com>
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* gimple-low.c (struct lower_data): Add cannot_fallthru field.
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(lower_stmt) <GIMPLE_BIND>: Add comment.
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<GIMPLE_COND, GIMPLE_GOTO, GIMPLE_SWITCH>: Set cannot_fallthru to true
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and return.
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<GIMPLE_RETURN>: Remove the statement if cannot_fallthru is set.
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Otherwise lower it and set cannot_fallthru to true.
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<GIMPLE_TRY>: Update cannot_fallthru for GIMPLE_TRY_FINALLY and return.
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<GIMPLE_CATCH, GIMPLE_EH_FILTER>; Set cannot_fallthru to false.
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<GIMPLE_CALL>: Set cannot_fallthru to false for BUILT_IN_SETJMP and
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to true for a noreturn call. Do not remove statements.
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<GIMPLE_OMP_PARALLEL, GIMPLE_OMP_TASK>: Set cannot_fallthru to false.
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Set cannot_fallthru to false on function exit.
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(gimple_stmt_may_fallthru) <GIMPLE_SWITCH>: Really return false.
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<GIMPLE_ASSIGN>: Remove.
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2009-10-19 Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
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* config/s390/s390.c (s390_z10_optimize_cmp): Don't touch FP compares.
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@ -76,6 +76,9 @@ struct lower_data
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of the function. */
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VEC(return_statements_t,heap) *return_statements;
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/* True if the current statement cannot fall through. */
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bool cannot_fallthru;
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/* True if the function calls __builtin_setjmp. */
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bool calls_builtin_setjmp;
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};
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@ -317,7 +320,12 @@ lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
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}
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/* Lower statement GSI. DATA is passed through the recursion. */
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/* Lower statement GSI. DATA is passed through the recursion. We try to
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track the fallthruness of statements and get rid of unreachable return
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statements in order to prevent the EH lowering pass from adding useless
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edges that can cause bogus warnings to be issued later; this guess need
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not be 100% accurate, simply be conservative and reset cannot_fallthru
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to false if we don't know. */
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static void
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lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
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@ -330,36 +338,61 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
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{
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case GIMPLE_BIND:
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lower_gimple_bind (gsi, data);
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/* Propagate fallthruness. */
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return;
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case GIMPLE_COND:
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/* The gimplifier has already lowered this into gotos. */
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break;
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case GIMPLE_GOTO:
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case GIMPLE_SWITCH:
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data->cannot_fallthru = true;
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gsi_next (gsi);
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return;
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case GIMPLE_RETURN:
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lower_gimple_return (gsi, data);
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if (data->cannot_fallthru)
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{
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gsi_remove (gsi, false);
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/* Propagate fallthruness. */
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}
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else
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{
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lower_gimple_return (gsi, data);
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data->cannot_fallthru = true;
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}
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return;
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case GIMPLE_TRY:
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lower_sequence (gimple_try_eval (stmt), data);
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lower_sequence (gimple_try_cleanup (stmt), data);
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{
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bool try_cannot_fallthru;
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lower_sequence (gimple_try_eval (stmt), data);
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try_cannot_fallthru = data->cannot_fallthru;
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data->cannot_fallthru = false;
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lower_sequence (gimple_try_cleanup (stmt), data);
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/* See gimple_stmt_may_fallthru for the rationale. */
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if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
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{
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data->cannot_fallthru |= try_cannot_fallthru;
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gsi_next (gsi);
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return;
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}
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}
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break;
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case GIMPLE_CATCH:
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data->cannot_fallthru = false;
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lower_sequence (gimple_catch_handler (stmt), data);
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break;
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case GIMPLE_EH_FILTER:
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data->cannot_fallthru = false;
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lower_sequence (gimple_eh_filter_failure (stmt), data);
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break;
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case GIMPLE_NOP:
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case GIMPLE_ASM:
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case GIMPLE_ASSIGN:
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case GIMPLE_GOTO:
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case GIMPLE_PREDICT:
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case GIMPLE_LABEL:
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case GIMPLE_SWITCH:
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case GIMPLE_EH_MUST_NOT_THROW:
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case GIMPLE_OMP_FOR:
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case GIMPLE_OMP_SECTIONS:
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@ -383,21 +416,16 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
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&& DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
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&& DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
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{
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data->calls_builtin_setjmp = true;
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lower_builtin_setjmp (gsi);
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data->cannot_fallthru = false;
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data->calls_builtin_setjmp = true;
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return;
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}
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/* After a noreturn call, remove a subsequent GOTO or RETURN that might
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have been mechanically added; this will prevent the EH lowering pass
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from adding useless edges and thus complicating the initial CFG. */
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if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
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{
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data->cannot_fallthru = true;
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gsi_next (gsi);
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if (!gsi_end_p (*gsi)
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&& (gimple_code (gsi_stmt (*gsi)) == GIMPLE_GOTO
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|| gimple_code (gsi_stmt (*gsi)) == GIMPLE_RETURN))
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gsi_remove (gsi, false);
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return;
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}
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}
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@ -405,13 +433,16 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
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case GIMPLE_OMP_PARALLEL:
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case GIMPLE_OMP_TASK:
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data->cannot_fallthru = false;
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lower_omp_directive (gsi, data);
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data->cannot_fallthru = false;
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return;
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default:
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gcc_unreachable ();
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}
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data->cannot_fallthru = false;
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gsi_next (gsi);
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}
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@ -660,9 +691,9 @@ gimple_stmt_may_fallthru (gimple stmt)
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return false;
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case GIMPLE_SWITCH:
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/* Switch has already been lowered and represents a
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branch to a selected label and hence can not fall through. */
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return true;
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/* Switch has already been lowered and represents a branch
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to a selected label and hence can't fall through. */
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return false;
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case GIMPLE_COND:
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/* GIMPLE_COND's are already lowered into a two-way branch. They
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@ -688,13 +719,10 @@ gimple_stmt_may_fallthru (gimple stmt)
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return (gimple_seq_may_fallthru (gimple_try_eval (stmt))
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&& gimple_seq_may_fallthru (gimple_try_cleanup (stmt)));
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case GIMPLE_ASSIGN:
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return true;
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case GIMPLE_CALL:
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/* Functions that do not return do not fall through. */
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return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
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default:
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return true;
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}
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@ -744,7 +772,7 @@ lower_gimple_return (gimple_stmt_iterator *gsi, struct lower_data *data)
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gsi_remove (gsi, false);
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}
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/* Lower a __builtin_setjmp TSI.
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/* Lower a __builtin_setjmp GSI.
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__builtin_setjmp is passed a pointer to an array of five words (not
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all will be used on all machines). It operates similarly to the C
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@ -1,3 +1,7 @@
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2009-10-19 Eric Botcazou <ebotcazou@adacore.com>
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* gnat.dg/noreturn2.ad[sb]: New test.
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2009-10-19 Tobias Burnus <burnus@net-b.de>
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PR fortran/41755
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23
gcc/testsuite/gnat.dg/noreturn2.adb
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23
gcc/testsuite/gnat.dg/noreturn2.adb
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@ -0,0 +1,23 @@
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-- { dg-do compile }
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package body Noreturn2 is
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procedure Raise_Exception_No_Defer (Message : String);
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pragma No_Return (Raise_Exception_No_Defer);
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procedure Raise_From (X : Exception_Occurrence) is
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Occurrence_Message : constant String := Exception_Message (X);
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begin
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if Occurrence_Message = "$" then
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Raise_Exception_No_Defer (Occurrence_Message);
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else
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Raise_Exception_No_Defer ("::" & Occurrence_Message);
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end if;
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end;
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procedure Raise_Exception_No_Defer (Message : String) is
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begin
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raise Program_Error;
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end;
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end Noreturn2;
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8
gcc/testsuite/gnat.dg/noreturn2.ads
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8
gcc/testsuite/gnat.dg/noreturn2.ads
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with Ada.Exceptions; use Ada.Exceptions;
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package Noreturn2 is
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procedure Raise_From (X : Exception_Occurrence);
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pragma No_Return (Raise_From);
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end Noreturn2;
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