Compilation in different directories not replacing absolute path of source file when using BASEDIR #1370

ribsthakkar · 2023-12-16T23:33:53Z

ribsthakkar
Dec 16, 2023

I am working on a project where I am compiling my project from two different directories /data/a/build and /data/b/build.

My ccache environment variables for directory a are:

]$ env | grep CCACHE
CCACHE_NOHASHDIR=true
CCACHE_DEBUG=true
CCACHE_DIR=/data/test_ccache/
CCACHE_NODIRECT=true
CCACHE_BASEDIR=/data/a
CCACHE_MAXSIZE=20G
CCACHE_DEBUGDIR=/data/test_ccache_debugdir/

My ccache environment variables for directory b are the same as above with the exception of base_dir, which is /data/b

I am using CMake with the Ninja generator, and I have several include args in my generated compile commands for my targets. And, as expected I correctly see in the ccache-log that the include files are being converted to relative paths with respect to my base_dir var. However, when I run an identical clone of my project in both directories, I don't get any hits. Upon investigating the .ccache-input-text for each of my targets, I see that the last arg (the source file arg) listed under the PREPROCESSOR MODE section is listed with its absolute path. Otherwise, there is no diff between the input-text. See below an example for target p1:

diff /data/test_ccache_debugdir/mnt/data/b/build/p1/CMakeFiles/p1.dir/src/main.
c.o.20231216_145253_249009.ccache-input-text /data/test_ccache_debugdir/mnt/data/a/build/p1/CMakeFiles/p1.dir/src/main.c.o.20
231216_143011_990800.ccache-input-text

131c131
< /data/b/p1/src/main.c
---
> /data/a/p1/src/main.c

There is a similar diff in the ccache-input-p files with this absolute path being included to the main.c in the very first line. The remaining of the binary is identical.

Below is a snippet of the input-text file from b before the preprocessor output begins confirming the diff above where we seemingly encode the absolute path to the source file:

### arg
-O0
### arg
-std=gnu11
### arg
-MD
-MT
-MF
### arg
-o
### arg
p1/CMakeFiles/p1.dir/src/main.c.o
### arg
-c
### arg
/data/b/p1/src/main.c
### cpp

Below is a snippet from the ccache-log file indicating the relative path conversion worked as expected when producing the pre-processor output:

[2023-12-16T14:52:53.249196 95474] Working directory: /var/mnt/data/b/build
[2023-12-16T14:52:53.249197 95474] Apparent working directory: /data/b/build
[2023-12-16T14:52:53.249207 95474] Compiler:  /usr/bin/gcc
[2023-12-16T14:52:53.249208 95474] Compiler type: gcc
[2023-12-16T14:52:53.249543 95474] Source file: ../p1/src/main.c
[2023-12-16T14:52:53.249545 95474] Dependency file: p1/CMakeFiles/p1.dir/src/main.c.o.d
[2023-12-16T14:52:53.249546 95474] Object file: p1/CMakeFiles/p1.dir/src/main.c.o
[2023-12-16T14:52:53.249883 95474] Running preprocessor
[2023-12-16T14:52:53.249901 95474] Executing /usr/bin/gcc -pipe -pthread -ffunction-sections -fdata-sections -msse4.2 -Wall -Wextra -Wpointer-arith -Wredundant-decls -Wshadow -Wconversion -Wfloat-equal -Wundef -Wwrite-strings -Wunreachable-code -ggdb3 -ffile-prefix-map=/data/b=. -fmacro-prefix-map=/data/b=. -frecord-gcc-switches -Wstrict-prototypes -Wnested-externs -O0 -std=gnu11 -  -I../PUBLIC -Ibuild_info -I../p1/ -I.. -I../p1/src  -E -o /run/user/12746/ccache-tmp/cpp_stdout.tmp.17FTjW.i ../p1/src/main.c
[2023-12-16T14:52:54.129904 95474] Got result key from preprocessor
[2023-12-16T14:52:54.129922 95474] Result key: 29bc3jivch600jgtbl3pco8hr9p02o4m8
[2023-12-16T14:52:54.129958 95474] No 29bc3jivch600jgtbl3pco8hr9p02o4m8 in local storage
[2023-12-16T14:52:54.129968 95474] Running real compiler

Is there another setting I am missing here?
Thanks!

jrosdahl · 2023-12-17T08:28:44Z

jrosdahl
Dec 17, 2023
Maintainer

### arg
-o
### arg
p1/CMakeFiles/p1.dir/src/main.c.o
### arg
-c
### arg
/data/b/p1/src/main.c

These are not supposed to be hashed as ### arg, so something unexpected is going on. Hard to say what since the most interesting parts of the log are left out. 🙂

Which ccache version are you using?

What is the full command line (Command line: ... in the log)?

4 replies

ribsthakkar Dec 17, 2023
Author

ah ok, I didn't realize how I should interpret the intput-text file. I assumed that was the input that was directly used to hash the files.
I can see the ### arg lines not being hashed since I assumed they were are comments, but I thought that the lines with the actual args themselves are included in the hash.
I am using ccache version 4.8.2.
Here's a larger snippet of the log:

[2023-12-16T14:52:53.249114 95474] === CCACHE 4.8.2 STARTED =========================================
[2023-12-16T14:52:53.249128 95474] Configuration file: /data/test_ccache/ccache.conf
[2023-12-16T14:52:53.249129 95474] System configuration file: /usr/local/etc/ccache.conf
[2023-12-16T14:52:53.249129 95474] Config: (default) absolute_paths_in_stderr = false
[2023-12-16T14:52:53.249129 95474] Config: (environment) base_dir = /data/b/
[2023-12-16T14:52:53.249129 95474] Config: (environment) cache_dir = /data/test_ccache/
[2023-12-16T14:52:53.249129 95474] Config: (default) compiler =
[2023-12-16T14:52:53.249129 95474] Config: (default) compiler_check = mtime
[2023-12-16T14:52:53.249129 95474] Config: (default) compiler_type = auto
[2023-12-16T14:52:53.249129 95474] Config: (default) compression = true
[2023-12-16T14:52:53.249129 95474] Config: (default) compression_level = 0
[2023-12-16T14:52:53.249129 95474] Config: (default) cpp_extension =
[2023-12-16T14:52:53.249129 95474] Config: (environment) debug = true
[2023-12-16T14:52:53.249129 95474] Config: (environment) debug_dir = /data/test_ccache_debugdir/
[2023-12-16T14:52:53.249129 95474] Config: (default) depend_mode = false
[2023-12-16T14:52:53.249129 95474] Config: (environment) direct_mode = false
[2023-12-16T14:52:53.249129 95474] Config: (default) disable = false
[2023-12-16T14:52:53.249129 95474] Config: (default) extra_files_to_hash =
[2023-12-16T14:52:53.249129 95474] Config: (default) file_clone = false
[2023-12-16T14:52:53.249129 95474] Config: (default) hard_link = false
[2023-12-16T14:52:53.249129 95474] Config: (environment) hash_dir = false
[2023-12-16T14:52:53.249129 95474] Config: (default) ignore_headers_in_manifest =
[2023-12-16T14:52:53.249129 95474] Config: (default) ignore_options =
[2023-12-16T14:52:53.249129 95474] Config: (default) inode_cache = true
[2023-12-16T14:52:53.249129 95474] Config: (default) keep_comments_cpp = false
[2023-12-16T14:52:53.249129 95474] Config: (default) log_file =
[2023-12-16T14:52:53.249129 95474] Config: (default) max_files = 0
[2023-12-16T14:52:53.249129 95474] Config: (environment) max_size = 20.0 GB
[2023-12-16T14:52:53.249129 95474] Config: (default) msvc_dep_prefix = Note: including file:
[2023-12-16T14:52:53.249129 95474] Config: (default) namespace =
[2023-12-16T14:52:53.249129 95474] Config: (default) path =
[2023-12-16T14:52:53.249129 95474] Config: (default) pch_external_checksum = false
[2023-12-16T14:52:53.249129 95474] Config: (default) prefix_command =
[2023-12-16T14:52:53.249129 95474] Config: (default) prefix_command_cpp =
[2023-12-16T14:52:53.249129 95474] Config: (default) read_only = false
[2023-12-16T14:52:53.249129 95474] Config: (default) read_only_direct = false
[2023-12-16T14:52:53.249129 95474] Config: (default) recache = false
[2023-12-16T14:52:53.249129 95474] Config: (default) remote_only = false
[2023-12-16T14:52:53.249129 95474] Config: (default) remote_storage =
[2023-12-16T14:52:53.249129 95474] Config: (default) reshare = false
[2023-12-16T14:52:53.249129 95474] Config: (default) run_second_cpp = true
[2023-12-16T14:52:53.249129 95474] Config: (default) sloppiness =
[2023-12-16T14:52:53.249129 95474] Config: (default) stats = true
[2023-12-16T14:52:53.249129 95474] Config: (environment) stats_log = /mnt/data/ccache_stats.log
[2023-12-16T14:52:53.249129 95474] Config: (default) temporary_dir = /run/user/12746/ccache-tmp
[2023-12-16T14:52:53.249129 95474] Config: (default) umask =
[2023-12-16T14:52:53.249192 95474] Command line: /data/b/x_ccache/ccache /usr/bin/gcc -I/data/b/PUBLIC -I/data/b/build/build_info -I/data/b/p1 -I/data/b -I/data/b/p1/src -pipe -pthread -ffunction-sections -fdata-sections -msse4.2 -Wall -Wextra -Werror -Wpointer-arith -Wredundant-decls -Wshadow -Wconversion -Wfloat-equal -Wundef -Wwrite-strings -Wunreachable-code -ggdb3 -ffile-prefix-map=/data/b=. -fmacro-prefix-map=/data/b=. -frecord-gcc-switches -Wstrict-prototypes -Wnested-externs -O0 -std=gnu11 -MD -MT p1/CMakeFiles/p1.dir/src/main.c.o -MF p1/CMakeFiles/p1.dir/src/main.c.o.d -o p1/CMakeFiles/p1.dir/src/main.c.o -c /data/b/p1/src/main.c
[2023-12-16T14:52:53.249195 95474] Hostname: xxxx
[2023-12-16T14:52:53.249196 95474] Working directory: /var/mnt/data/b/build
[2023-12-16T14:52:53.249197 95474] Apparent working directory: /data/b/build
[2023-12-16T14:52:53.249207 95474] Compiler: /usr/bin/gcc
[2023-12-16T14:52:53.249208 95474] Compiler type: gcc
[2023-12-16T14:52:53.249543 95474] Source file: ../p1/src/main.c
[2023-12-16T14:52:53.249545 95474] Dependency file: p1/CMakeFiles/p1.dir/src/main.c.o.d
[2023-12-16T14:52:53.249546 95474] Object file: p1/CMakeFiles/p1.dir/main.c.o
[2023-12-16T14:52:53.249883 95474] Running preprocessor
[2023-12-16T14:52:53.249901 95474] Executing /usr/bin/gcc -pipe -pthread -ffunction-sections -fdata-sections -msse4.2 -Wall -Wextra -Wpointer-arith -Wredundant-decls -Wshadow -Wconversion -Wfloat-equal -Wundef -Wwrite-strings -Wunreachable-code -ggdb3 -ffile-prefix-map=/data/b=. -fmacro-prefix-map=/data/b=. -frecord-gcc-switches -Wstrict-prototypes -Wnested-externs -O0 -std=gnu11 -  -I../PUBLIC -Ibuild_info -I../p1/ -I.. -I../p1/src  -E -o /run/user/12746/ccache-tmp/cpp_stdout.tmp.17FTjW.i ../p1/src/main.c
[2023-12-16T14:52:54.129904 95474] Got result key from preprocessor
[2023-12-16T14:52:54.129922 95474] Result key: 29bc3jivch600jgtbl3pco8hr9p02o4m8
[2023-12-16T14:52:54.129958 95474] No 29bc3jivch600jgtbl3pco8hr9p02o4m8 in local storage

jrosdahl Dec 17, 2023
Maintainer

Ah, now I found it. It's -frecord-gcc-switches (didn't notice it before) that puts ccache into "hash the full command line" mode since ccache otherwise will risk delivering incorrect object files from the cache. See #804.

ribsthakkar Dec 18, 2023
Author

Ahhh I see. Thanks for pointing it out.

Is it in the docs somewhere? Sorry if I missed it. Otherwise, I think it would be helpful if the docs had a dedicated list of compiler args that are unsupported or have some special restrictions.

jrosdahl Dec 18, 2023
Maintainer

No, there is no such list currently.

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