Re: [ccache] [PATCH] Support for Clang precompiled headers
On Thursday 12 of July 2012, Joel Rosdahl wrote:
On 6 July 2012 19:09, Lubos Lunak l.lu...@suse.cz wrote:
the attached patches modify ccache to also support Clang PCH in addition
to GCC PCH.
Thanks!
Regarding 0002-hash-clang-s-.pch-file-explicitly.patch: Why is the third
assignment of pch_file done outside the if (stat(pchpath, st) == 0)
block? This means that pch_file and included_pch_file can be set even when
there is no .pch file, so remember_include_file will fail to stat the file
and then turn off the direct mode. The test suite also fails after the
patch, but passes if the pch_file assignment is moved into the block.
Right. I guess that was an oversight when I moved the Multiple precompiled
headers used error to one place. Fixed version attached.
The patches look good otherwise.
PS: Since I've noticed in the archives the recent mail about issues with
ccache and warnings about unused arguments: The proper way to use ccache
with Clang is to set CCACHE_CPP2, which not only avoids these warnings,
but in general Clang works suboptimally if passed preprocessed output
(warning/error messages quoting sources are affected, some warnings are
not supressed in headers).
Do you have any idea about the performance impact of using CCACHE_CPP2 for
clang?
Debug build of LibreOffice, warm disk caches, empty ccache, make -j4 in
xmloff module:
CCACHE_CPP2=1:
494.64user 34.99system 2:15.60elapsed 390%CPU (0avgtext+0avgdata
1309824maxresident)k
0inputs+3752560outputs (507major+13592550minor)pagefaults 0swaps
not set:
457.17user 28.94system 2:06.15elapsed 385%CPU (0avgtext+0avgdata
1309312maxresident)k
0inputs+3758600outputs (444major+12098612minor)pagefaults 0swaps
So in this case CCACHE_CPP2 adds about 8% overhead. It might make a
difference for somebody, but I myself would prefer to get better error
messages from Clang (and I actually use ccache only for a buildbot, so I
don't find this worth the effort).
If somebody would feel like playing with this, note that Clang 3.2 will
have -E -Wp,-rewrite-includes, which only processes #include directives and
nothing more (I wrote the feature to solve a similar problem when using Clang
with Icecream for distributed builds, and I assume this is the only thing
ccache in fact wants from -E too). So using this in ccache for Clang should
presumably reduce this overhead.
--
Lubos Lunak
l.lu...@suse.cz
From d897f0388b35ca0b8e333e7e8edbd57a0c4ba3e1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lubo=C5=A1=20Lu=C5=88=C3=A1k?= l.lu...@suse.cz
Date: Fri, 6 Jul 2012 18:45:05 +0200
Subject: [PATCH 2/2] hash clang's .pch file explicitly
It does not appear anywhere in the preprocessed output, so
process_preprocessed_file() would miss it.
---
ccache.c | 31 +++
1 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/ccache.c b/ccache.c
index 12b62a4..926d6b2 100644
--- a/ccache.c
+++ b/ccache.c
@@ -171,6 +171,11 @@ static bool profile_generate = false;
*/
static bool using_precompiled_header = false;
+/*
+ * The .gch/.pch file used for compilation.
+ */
+static char *included_pch_file = NULL;
+
/* How long (in microseconds) to wait before breaking a stale lock. */
unsigned lock_staleness_limit = 200;
@@ -532,6 +537,16 @@ process_preprocessed_file(struct mdfour *hash, const char *path)
hash_buffer(hash, p, (end - p));
free(data);
+
+ /* Explicitly check the .gch/.pch file, Clang does not include any mention of it
+ in the preprocessed output. */
+ if (included_pch_file) {
+ char *path = x_strdup(included_pch_file);
+ path = make_relative_path(path);
+ hash_string(hash, path);
+ remember_include_file(path, strlen(included_pch_file), hash);
+ }
+
return true;
}
@@ -1680,6 +1695,7 @@ cc_process_args(struct args *orig_args, struct args **preprocessor_args,
*/
if (compopt_takes_path(argv[i])) {
char *relpath;
+ char *pch_file = NULL;
if (i == argc-1) {
cc_log(Missing argument to %s, argv[i]);
stats_update(STATS_ARGS);
@@ -1696,23 +1712,37 @@ cc_process_args(struct args *orig_args, struct args **preprocessor_args,
if (stat(argv[i+1], st) == 0) {
cc_log(Detected use of precompiled header: %s, argv[i+1]);
found_pch = true;
+ pch_file = x_strdup(argv[i+1]);
}
} else {
char* gchpath = format(%s.gch, argv[i+1]);
if (stat(gchpath, st) == 0) {
cc_log(Detected use of precompiled header: %s, gchpath);
found_pch = true;
+ pch_file = x_strdup(gchpath);
} else {
char* pchpath = format(%s.pch, argv[i+1]);
if (stat(pchpath, st) == 0) {
cc_log(Detected use of precompiled header: %s, pchpath);
found_pch = true;
+ pch_file = x_strdup(pchpath);
}
free(pchpath);
}
free(gchpath);
}
+ if (pch_file) {
+if (included_pch_file) {
+ cc_log(Multiple precompiled headers used: %s and %s\n,
+ included_pch_file, pch_file);
+
Re: [ccache] [PATCH] Support for Clang precompiled headers
On 13 July 2012 11:48, Lubos Lunak l.lu...@suse.cz wrote: Right. I guess that was an oversight when I moved the Multiple precompiled headers used error to one place. Fixed version attached. Thanks, applied. -- Joel ___ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
[ccache] [PATCH] Support for Clang precompiled headers
Hello,
the attached patches modify ccache to also support Clang PCH in addition to
GCC PCH.
The changes are:
- Clang uses .pch as the extension, not .gch
- the .pch file can be directly passed using -include-pch, instead of
using -include and trying to find the .pch file
- the use of a .pch is not reflected in the resulting .ii , so it needs to be
explicitly added to the hash for checking if used files have changed
- I also believe that path_len passed to remember_include_file() is incorrect,
as make_relative_path() may change the string
PS: Since I've noticed in the archives the recent mail about issues with
ccache and warnings about unused arguments: The proper way to use ccache with
Clang is to set CCACHE_CPP2, which not only avoids these warnings, but in
general Clang works suboptimally if passed preprocessed output (warning/error
messages quoting sources are affected, some warnings are not supressed in
headers).
--
Lubos Lunak
l.lu...@suse.cz
From 768ffacb434d116759fc73cf0d2723aba6b5af4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lubo=C5=A1=20Lu=C5=88=C3=A1k?= l.lu...@suse.cz
Date: Fri, 6 Jul 2012 18:09:36 +0200
Subject: [PATCH 1/3] support for precompiled headers with clang
Support the clang-specific -include-pch option, which references
the PCH file itself, and support the .pch extension when using
the gcc -include way.
---
MANUAL.txt |2 ++
ccache.c | 29 +
compopt.c |1 +
3 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/MANUAL.txt b/MANUAL.txt
index 4be33ae..478d36b 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -629,6 +629,8 @@ things to make it work properly:
--
** use the *-include* compiler option to include the precompiled header
(i.e., don't use *#include* in the source code to include the header); or
+** (Clang compiler) use the *-include-pch* compiler option to include
+ the PCH file generated from the precompiled header; or
** add the *-fpch-preprocess* compiler option when compiling.
If you don't do this, either the non-precompiled version of the header file
diff --git a/ccache.c b/ccache.c
index 8b50c36..12b62a4 100644
--- a/ccache.c
+++ b/ccache.c
@@ -167,7 +167,7 @@ static bool profile_use = false;
static bool profile_generate = false;
/*
- * Whether we are using a precompiled header (either via -include or #include).
+ * Whether we are using a precompiled header (either via -include, #include or clang's -include-pch).
*/
static bool using_precompiled_header = false;
@@ -1355,7 +1355,7 @@ find_compiler(char** argv)
bool
is_precompiled_header(const char *path)
{
- return str_eq(get_extension(path), .gch);
+ return str_eq(get_extension(path), .gch) || str_eq(get_extension(path), .pch);
}
/*
@@ -1680,7 +1680,6 @@ cc_process_args(struct args *orig_args, struct args **preprocessor_args,
*/
if (compopt_takes_path(argv[i])) {
char *relpath;
- char *pchpath;
if (i == argc-1) {
cc_log(Missing argument to %s, argv[i]);
stats_update(STATS_ARGS);
@@ -1693,13 +1692,27 @@ cc_process_args(struct args *orig_args, struct args **preprocessor_args,
args_add(stripped_args, relpath);
/* Try to be smart about detecting precompiled headers */
- pchpath = format(%s.gch, argv[i+1]);
- if (stat(pchpath, st) == 0) {
-cc_log(Detected use of precompiled header: %s, pchpath);
-found_pch = true;
+ if (str_eq(argv[i], -include-pch)) {
+if (stat(argv[i+1], st) == 0) {
+ cc_log(Detected use of precompiled header: %s, argv[i+1]);
+ found_pch = true;
+}
+ } else {
+char* gchpath = format(%s.gch, argv[i+1]);
+if (stat(gchpath, st) == 0) {
+ cc_log(Detected use of precompiled header: %s, gchpath);
+ found_pch = true;
+} else {
+ char* pchpath = format(%s.pch, argv[i+1]);
+ if (stat(pchpath, st) == 0) {
+ cc_log(Detected use of precompiled header: %s, pchpath);
+ found_pch = true;
+ }
+ free(pchpath);
+}
+free(gchpath);
}
- free(pchpath);
free(relpath);
i++;
continue;
diff --git a/compopt.c b/compopt.c
index 77b57f5..908302e 100644
--- a/compopt.c
+++ b/compopt.c
@@ -61,6 +61,7 @@ static const struct compopt compopts[] = {
{-imacros,AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
{-imultilib, AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
{-include,AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
+ {-include-pch,AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
{-install_name, TAKES_ARG}, /* Darwin linker option */
{-iprefix,AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
{-iquote, AFFECTS_CPP | TAKES_ARG | TAKES_PATH},
--
1.7.7
From bbfc0ed55a6f730023d068773fc9fece16b94c74 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lubo=C5=A1=20Lu=C5=88=C3=A1k?= l.lu...@suse.cz
Date: Fri, 6 Jul 2012 18:46:25 +0200
Subject: [PATCH 3/3] do not pass incorrect length to remember_include_file()
---
ccache.c |7 ---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git
