mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2025-04-06 02:20:34 +08:00
Code Issues Packages Projects Releases Wiki Activity

Fix miscompilation of Python on HP-PA/Linux

Browse Source 
This is the miscompilation of Python at -O2 on HP-PA/Linux present
on the mainline and 10 branch, caused by the presence of a call to
__builtin_unreachable () in the middle of a heavily branchy code,
which confuses the reorg pass.

gcc/
	PR rtl-optimization/96015
	* reorg.c (skip_consecutive_labels): Minor comment tweaks.
	(relax_delay_slots): When deleting a jump to the next active
	instruction over a barrier, first delete the barrier if the
	jump is the only way to reach the target label.
This commit is contained in:
Eric Botcazou 2021-02-09 19:49:18 +01:00
parent a11ef53238
commit 20f28986a8
1 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
gcc/reorg.c
View File

@ -139,9 +139,9 @@ skip_consecutive_labels (rtx label_or_return)
/* __builtin_unreachable can create a CODE_LABEL followed by a BARRIER.
Since reaching the CODE_LABEL is undefined behavior, we can return
any code label and we're OK at runtime.
any code label and we're OK at run time.
However, if we return a CODE_LABEL which leads to a shrinked wrapped
However, if we return a CODE_LABEL which leads to a shrink-wrapped
epilogue, but the path does not have a prologue, then we will trip
a sanity check in the dwarf2 cfi code which wants to verify that
the CFIs are all the same on the traces leading to the epilogue.
@ -3210,6 +3210,23 @@ relax_delay_slots (rtx_insn *first)
&& ! condjump_in_parallel_p (jump_insn)
&& ! (next && switch_text_sections_between_p (jump_insn, next)))
{
rtx_insn *direct_label = as_a<rtx_insn *> (JUMP_LABEL (insn));
rtx_insn *prev = prev_nonnote_insn (direct_label);
/* If the insn jumps over a BARRIER and is the only way to reach
its target, then we need to delete the BARRIER before the jump
because, otherwise, the target may end up being considered as
unreachable and thus also deleted. */
if (BARRIER_P (prev) && LABEL_NUSES (direct_label) == 1)
{
delete_related_insns (prev);
/* We have just removed a BARRIER, which means that the block
number of the next insns has effectively been changed (see
find_basic_block in resource.c), so clear it. */
clear_hashed_info_until_next_barrier (direct_label);
}
delete_jump (jump_insn);
continue;
}