Alex Richardson has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/54525 )
Change subject: scons: avoid rebuilding sim/tags.cc when unchanged
......................................................................
scons: avoid rebuilding sim/tags.cc when unchanged
Previously a no-changes incremental build of build/RISCV/gem5.debug would
result in the following build steps being performed:
```
[VER TAGS] -> RISCV/sim/tags.cc
[ CXX] RISCV/sim/tags.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/DMA_Controller.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/DMA_Wakeup.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/Directory_Controller.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/Directory_Wakeup.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/L1Cache_Controller.cc -> .do
[ CXX] RISCV/mem/ruby/protocol/L1Cache_Wakeup.cc -> .do
[ CXX] RISCV/base/date.cc -> .do
[ LINK] -> RISCV/gem5.debug
```
This commit adds a --output-file flag to cpt_updater.py that only updates
the output file if the contents has changed. With this change a no-changes
build only prints the following (and avoids the expensive LINK step):
```
[VER TAGS] -> RISCV/sim/tags.cc
scons: `build/RISCV/gem5.debug' is up to date.
```
Change-Id: If33cfd4ccb10dd4a55495c188a1c77845f340f69
---
M util/cpt_upgrader.py
M src/SConscript
2 files changed, 68 insertions(+), 13 deletions(-)
diff --git a/src/SConscript b/src/SConscript
index e40262a..127f28c 100644
--- a/src/SConscript
+++ b/src/SConscript
@@ -809,7 +809,7 @@
# version tags
tags = \
env.Command('sim/tags.cc', None,
- MakeAction('util/cpt_upgrader.py --get-cc-file > $TARGET',
+ MakeAction('util/cpt_upgrader.py --get-cc-file -o $TARGET',
Transform("VER TAGS")))
env.AlwaysBuild(tags)
diff --git a/util/cpt_upgrader.py b/util/cpt_upgrader.py
index abbaba2..5f76e62 100755
--- a/util/cpt_upgrader.py
+++ b/util/cpt_upgrader.py
@@ -72,6 +72,7 @@
import configparser
import glob, types, sys, os
import os.path as osp
+from pathlib import Path
verbose_print = False
@@ -281,6 +282,10 @@
"--get-cc-file", action="store_true",
# used during build; generate src/sim/tags.cc and exit
help=SUPPRESS)
+ parser.add_argument(
+ "-o", "--output-file", default="-",
+ help="The output file for --get-cc-file (default=stdout)."
+ "If specified this program will not update an unchanged
file.")
parser.add_argument("checkpoint", nargs='?')
args = parser.parse_args()
@@ -289,19 +294,37 @@
Upgrader.load_all()
if args.get_cc_file:
- print("// this file is auto-generated by util/cpt_upgrader.py")
- print("#include <string>")
- print("#include <set>")
- print()
- print("namespace gem5")
- print("{")
- print()
- print("std::set<std::string> version_tags = {")
+ contents = """// this file is auto-generated by
util/cpt_upgrader.py
+#include <set>
+#include <string>
+
+namespace gem5
+{
+
+std::set<std::string> version_tags = {
+"""
for tag in sorted(Upgrader.tag_set):
- print(" \"{}\",".format(tag))
- print("};")
- print()
- print("} // namespace gem5")
+ contents += " \"{}\",\n".format(tag)
+ contents += """};
+
+} // namespace gem5
+"""
+ if args.output_file == "-":
+ sys.stdout.write(contents)
+ exit(0)
+ # Otherwise, check if the file already exists and if so only
overwrite
+ # it if the contents is different. This avoids unnecessary
rebuilds.
+ output_file = Path(args.output_file)
+ if output_file.exists():
+ existing_contents = output_file.read_text(encoding="utf-8")
+ if existing_contents == contents:
+ verboseprint("Existing file", output_file,
+ "matches generated contents.")
+ exit(0)
+ else:
+ verboseprint("Overwriting", output_file,
+ "with new generated contents.")
+ output_file.write_text(contents, encoding="utf-8")
exit(0)
elif not args.checkpoint:
parser.error("You must specify a checkpoint file to modify or a "
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: If33cfd4ccb10dd4a55495c188a1c77845f340f69
Gerrit-Change-Number: 54525
Gerrit-PatchSet: 1
Gerrit-Owner: Alex Richardson <alexrichard...@google.com>
Gerrit-MessageType: newchange
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