---
gcc/common.opt | 4 ++++
gcc/common.opt.urls | 3 +++
gcc/doc/invoke.texi | 8 ++++++++
gcc/opts.cc | 1 +
4 files changed, 16 insertions(+)
diff --git a/gcc/common.opt b/gcc/common.opt
index 40cab3cb36a..5710e817abe 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2163,6 +2163,10 @@ fira-share-spill-slots
Common Var(flag_ira_share_spill_slots) Init(1) Optimization
Share stack slots for spilled pseudo-registers.
+ftrack-subreg-liveness
+Common Var(flag_track_subreg_liveness) Init(0) Optimization
+Track subreg liveness information.
+
fira-verbose=
Common RejectNegative Joined UInteger Var(flag_ira_verbose) Init(5)
-fira-verbose=<number> Control IRA's level of diagnostic messages.
diff --git a/gcc/common.opt.urls b/gcc/common.opt.urls
index f71ed80a34b..59f27a6f7c6 100644
--- a/gcc/common.opt.urls
+++ b/gcc/common.opt.urls
@@ -880,6 +880,9 @@
UrlSuffix(gcc/Optimize-Options.html#index-fira-share-save-slots)
fira-share-spill-slots
UrlSuffix(gcc/Optimize-Options.html#index-fira-share-spill-slots)
+ftrack-subreg-liveness
+UrlSuffix(gcc/Optimize-Options.html#index-ftrack-subreg-liveness)
+
fira-verbose=
UrlSuffix(gcc/Developer-Options.html#index-fira-verbose)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ddcd5213f06..fbcde8aa745 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -13188,6 +13188,14 @@ Disable sharing of stack slots allocated for
pseudo-registers. Each
pseudo-register that does not get a hard register gets a separate
stack slot, and as a result function stack frames are larger.
+@opindex ftrack-subreg-liveness
+@item -ftrack-subreg-liveness
+Enable tracking subreg liveness information. This infomation allows IRA
+and LRA to support subreg coalesce feature which can improve the quality
+of register allocation.
+
+This option is enabled at level @option{-O3} for all targets.
+
@opindex flra-remat
@item -flra-remat
Enable CFG-sensitive rematerialization in LRA. Instead of loading
diff --git a/gcc/opts.cc b/gcc/opts.cc
index 14d1767e48f..8fe3a213807 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -698,6 +698,7 @@ static const struct default_options default_options_table[]
=
{ OPT_LEVELS_3_PLUS, OPT_funswitch_loops, NULL, 1 },
{ OPT_LEVELS_3_PLUS, OPT_fvect_cost_model_, NULL, VECT_COST_MODEL_DYNAMIC
},
{ OPT_LEVELS_3_PLUS, OPT_fversion_loops_for_strides, NULL, 1 },
+ { OPT_LEVELS_3_PLUS, OPT_ftrack_subreg_liveness, NULL, 1 },
/* -O3 parameters. */
{ OPT_LEVELS_3_PLUS, OPT__param_max_inline_insns_auto_, NULL, 30 },
--
2.36.3
