LGTM! Thanks!
在 2023/6/14 上午8:43, Xi Ruoyao 写道:
The LA464 micro-architecture is sensitive to alignment of code. The
Loongson team has benchmarked various combinations of function, the
results [1] show that 16-byte label alignment together with 32-byte
function alignment gives best results in terms of SPEC score.
Add a mtune-based table-driven mechanism to set the default of
-falign-{functions,labels}. As LA464 is the first (and the only for
now) uarch supported by GCC, the same setting is also used for
the "generic" -mtune=loongarch64. In the future we may set different
settings for LA{2,3,6}64 once we add the support for them.
Bootstrapped and regtested on loongarch64-linux-gnu. Ok for trunk?
gcc/ChangeLog:
* config/loongarch/loongarch-tune.h (loongarch_align): New
struct.
* config/loongarch/loongarch-def.h (loongarch_cpu_align): New
array.
* config/loongarch/loongarch-def.c (loongarch_cpu_align): Define
the array.
* config/loongarch/loongarch.cc
(loongarch_option_override_internal): Set the value of
-falign-functions= if -falign-functions is enabled but no value
is given. Likewise for -falign-labels=.
---
gcc/config/loongarch/loongarch-def.c | 12 ++++++++++++
gcc/config/loongarch/loongarch-def.h | 1 +
gcc/config/loongarch/loongarch-tune.h | 8 ++++++++
gcc/config/loongarch/loongarch.cc | 6 ++++++
4 files changed, 27 insertions(+)
diff --git a/gcc/config/loongarch/loongarch-def.c
b/gcc/config/loongarch/loongarch-def.c
index fc4ebbefede..6729c857f7c 100644
--- a/gcc/config/loongarch/loongarch-def.c
+++ b/gcc/config/loongarch/loongarch-def.c
@@ -72,6 +72,18 @@ loongarch_cpu_cache[N_TUNE_TYPES] = {
},
};
+struct loongarch_align
+loongarch_cpu_align[N_TUNE_TYPES] = {
+ [CPU_LOONGARCH64] = {
+ .function = "32",
+ .label = "16",
+ },
+ [CPU_LA464] = {
+ .function = "32",
+ .label = "16",
+ },
+};
+
/* The following properties cannot be looked up directly using "cpucfg".
So it is necessary to provide a default value for "unknown native"
tune targets (i.e. -mtune=native while PRID does not correspond to
diff --git a/gcc/config/loongarch/loongarch-def.h
b/gcc/config/loongarch/loongarch-def.h
index 778b1409956..fb8bb88eb52 100644
--- a/gcc/config/loongarch/loongarch-def.h
+++ b/gcc/config/loongarch/loongarch-def.h
@@ -144,6 +144,7 @@ extern int loongarch_cpu_issue_rate[];
extern int loongarch_cpu_multipass_dfa_lookahead[];
extern struct loongarch_cache loongarch_cpu_cache[];
+extern struct loongarch_align loongarch_cpu_align[];
extern struct loongarch_rtx_cost_data loongarch_cpu_rtx_cost_data[];
#ifdef __cplusplus
diff --git a/gcc/config/loongarch/loongarch-tune.h
b/gcc/config/loongarch/loongarch-tune.h
index ba31c4f08c3..5c03262daff 100644
--- a/gcc/config/loongarch/loongarch-tune.h
+++ b/gcc/config/loongarch/loongarch-tune.h
@@ -48,4 +48,12 @@ struct loongarch_cache {
int simultaneous_prefetches; /* number of parallel prefetch */
};
+/* Alignment for functions and labels for best performance. For new uarchs
+ the value should be measured via benchmarking. See the documentation for
+ -falign-functions and -falign-labels in invoke.texi for the format. */
+struct loongarch_align {
+ const char *function; /* default value for -falign-functions */
+ const char *label; /* default value for -falign-labels */
+};
+
#endif /* LOONGARCH_TUNE_H */
diff --git a/gcc/config/loongarch/loongarch.cc
b/gcc/config/loongarch/loongarch.cc
index eb73d11b869..5b8b93eb24b 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -6249,6 +6249,12 @@ loongarch_option_override_internal (struct gcc_options
*opts)
&& !opts->x_optimize_size)
opts->x_flag_prefetch_loop_arrays = 1;
+ if (opts->x_flag_align_functions && !opts->x_str_align_functions)
+ opts->x_str_align_functions =
loongarch_cpu_align[LARCH_ACTUAL_TUNE].function;
+
+ if (opts->x_flag_align_labels && !opts->x_str_align_labels)
+ opts->x_str_align_labels = loongarch_cpu_align[LARCH_ACTUAL_TUNE].label;
+
if (TARGET_DIRECT_EXTERN_ACCESS && flag_shlib)
error ("%qs cannot be used for compiling a shared library",
"-mdirect-extern-access");
