diff options
Diffstat (limited to '0137-Backport-SME-mode-switching-Tweak-entry-exit-handlin.patch')
| -rw-r--r-- | 0137-Backport-SME-mode-switching-Tweak-entry-exit-handlin.patch | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/0137-Backport-SME-mode-switching-Tweak-entry-exit-handlin.patch b/0137-Backport-SME-mode-switching-Tweak-entry-exit-handlin.patch new file mode 100644 index 0000000..8444847 --- /dev/null +++ b/0137-Backport-SME-mode-switching-Tweak-entry-exit-handlin.patch @@ -0,0 +1,92 @@ +From c0aaf329d9c547b249ac120a8d1995d8546a1edb Mon Sep 17 00:00:00 2001 +From: Richard Sandiford <richard.sandiford@arm.com> +Date: Sat, 11 Nov 2023 17:28:57 +0000 +Subject: [PATCH 038/157] [Backport][SME] mode-switching: Tweak entry/exit + handling + +Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=e59ec35276599805cdc6c3979d8a167b027d286e + +An entity isn't transparent in a block that requires a specific mode. +optimize_mode_switching took that into account for normal insns, +but didn't for the exit block. Later patches misbehaved because +of this. + +In contrast, an entity was correctly marked as non-transparent +in the entry block, but the reasoning seemed a bit convoluted. +It also referred to a function that no longer exists. +Since KILL = ~TRANSP, the entity is by definition not transparent +in a block that defines the entity, so I think we can make it so +without comment. + +Finally, the exit handling was nested in the entry handling, +but that doesn't seem necessary. A target could say that an +entity is undefined on entry but must be defined on return, +on a "be liberal in what you accept, be conservative in what +you do" principle. + +gcc/ + * mode-switching.cc (optimize_mode_switching): Mark the exit + block as nontransparent if it requires a specific mode. + Handle the entry and exit mode as sibling rather than nested + concepts. Remove outdated comment. +--- + gcc/mode-switching.cc | 34 +++++++++++++++------------------- + 1 file changed, 15 insertions(+), 19 deletions(-) + +diff --git a/gcc/mode-switching.cc b/gcc/mode-switching.cc +index 4d2b9e284..4761c2ff0 100644 +--- a/gcc/mode-switching.cc ++++ b/gcc/mode-switching.cc +@@ -649,34 +649,30 @@ optimize_mode_switching (void) + } + if (targetm.mode_switching.entry && targetm.mode_switching.exit) + { +- int mode = targetm.mode_switching.entry (e); +- + info[post_entry->index].mode_out = + info[post_entry->index].mode_in = no_mode; +- if (pre_exit) +- { +- info[pre_exit->index].mode_out = +- info[pre_exit->index].mode_in = no_mode; +- } + ++ int mode = targetm.mode_switching.entry (e); + if (mode != no_mode) + { +- bb = post_entry; +- +- /* By always making this nontransparent, we save +- an extra check in make_preds_opaque. We also +- need this to avoid confusing pre_edge_lcm when +- antic is cleared but transp and comp are set. */ +- bitmap_clear_bit (transp_all, bb->index); +- + /* Insert a fake computing definition of MODE into entry + blocks which compute no mode. This represents the mode on + entry. */ +- info[bb->index].computing = mode; ++ info[post_entry->index].computing = mode; ++ bitmap_clear_bit (transp_all, post_entry->index); ++ } + +- if (pre_exit) +- info[pre_exit->index].seginfo->mode = +- targetm.mode_switching.exit (e); ++ if (pre_exit) ++ { ++ info[pre_exit->index].mode_out = ++ info[pre_exit->index].mode_in = no_mode; ++ ++ int mode = targetm.mode_switching.exit (e); ++ if (mode != no_mode) ++ { ++ info[pre_exit->index].seginfo->mode = mode; ++ bitmap_clear_bit (transp_all, pre_exit->index); ++ } + } + } + +-- +2.33.0 + |