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author | Eric Botcazou <ebotcazou@adacore.com> | 2020-09-16 13:06:34 +0200 |
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committer | Eric Botcazou <ebotcazou@adacore.com> | 2020-09-16 17:42:51 +0200 |
commit | aab6194d0898f5c592708fe2d44a14046b4d9097 (patch) | |
tree | e8cbe88c94b858475d9c3d28b8062b08fdf68afd | |
parent | 7d1be939e0fbc5ce63ba17db3d20ccc39ac17527 (diff) | |
download | gcc-aab6194d0898f5c592708fe2d44a14046b4d9097.zip gcc-aab6194d0898f5c592708fe2d44a14046b4d9097.tar.gz gcc-aab6194d0898f5c592708fe2d44a14046b4d9097.tar.bz2 |
Fix pessimization in EH cleanup pass
This restores the post-order traversal done by cleanup_all_empty_eh in
order to eliminate empty landing pads and also contains a small tweak
to the line debug info to avoid a problematic inheritance for coverage
measurement.
gcc/ChangeLog:
* tree-eh.c (lower_try_finally_dup_block): Backward propagate slocs
to stack restore builtin calls.
(cleanup_all_empty_eh): Do again a post-order traversal of the EH
region tree.
gcc/testsuite/ChangeLog:
* gnat.dg/concat4.adb: New test.
-rw-r--r-- | gcc/testsuite/gnat.dg/concat4.adb | 17 | ||||
-rw-r--r-- | gcc/tree-eh.c | 22 |
2 files changed, 32 insertions, 7 deletions
diff --git a/gcc/testsuite/gnat.dg/concat4.adb b/gcc/testsuite/gnat.dg/concat4.adb new file mode 100644 index 0000000..fe3f4ed --- /dev/null +++ b/gcc/testsuite/gnat.dg/concat4.adb @@ -0,0 +1,17 @@ +-- { dg-do compile } + +with Ada.Text_IO; use Ada.Text_IO; + +procedure Concat4 (X : Integer) is + Ximg : constant String := Integer'Image (X); +begin + if X > 0 then + Put_Line (Ximg & " is Positive"); + elsif X < 0 then + Put_Line (Ximg & " is Negative"); + else + Put_Line (Ximg & " is Null"); + end if; +end; + +-- { dg-final { scan-assembler-not "_Unwind_Resume" } } diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c index 4246dca..1376b82 100644 --- a/gcc/tree-eh.c +++ b/gcc/tree-eh.c @@ -899,23 +899,26 @@ lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state, gtry *region = NULL; gimple_seq new_seq; gimple_stmt_iterator gsi; + location_t last_loc = UNKNOWN_LOCATION; new_seq = copy_gimple_seq_and_replace_locals (seq); - for (gsi = gsi_start (new_seq); !gsi_end_p (gsi); gsi_next (&gsi)) + for (gsi = gsi_last (new_seq); !gsi_end_p (gsi); gsi_prev (&gsi)) { gimple *stmt = gsi_stmt (gsi); /* We duplicate __builtin_stack_restore at -O0 in the hope of eliminating - it on the EH paths. When it is not eliminated, make it transparent in - the debug info. */ + it on the EH paths. When it is not eliminated, give it the next + location in the sequence or make it transparent in the debug info. */ if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) - gimple_set_location (stmt, UNKNOWN_LOCATION); + gimple_set_location (stmt, last_loc); else if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION) { tree block = gimple_block (stmt); gimple_set_location (stmt, loc); gimple_set_block (stmt, block); } + else + last_loc = gimple_location (stmt); } if (outer_state->tf) @@ -4751,9 +4754,9 @@ cleanup_all_empty_eh (void) eh_landing_pad lp; int i; - /* Ideally we'd walk the region tree and process LPs inner to outer - to avoid quadraticness in EH redirection. Walking the LP array - in reverse seems to be an approximation of that. */ + /* The post-order traversal may lead to quadraticness in the redirection + of incoming EH edges from inner LPs, so first try to walk the region + tree from inner to outer LPs in order to eliminate these edges. */ for (i = vec_safe_length (cfun->eh->lp_array) - 1; i >= 1; --i) { lp = (*cfun->eh->lp_array)[i]; @@ -4761,6 +4764,11 @@ cleanup_all_empty_eh (void) changed |= cleanup_empty_eh (lp); } + /* Now do the post-order traversal to eliminate outer empty LPs. */ + for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i) + if (lp) + changed |= cleanup_empty_eh (lp); + return changed; } |