Re: [ccache] -Bprefix compiler option - resulting in cache miss

[Joel Rosdahl]

On 11 September 2015 at 12:02, vkr  wrote:

> I believe I found a potential bug with ccache that results in cache-miss if
> -Bprfix compilation option is used, where prefix specifies where to find
> the executables, libraries, include files, and data files of the compiler
> itself. [...]
>

I would rather call it "not yet supported" than a bug. :-) But yes, your
observation is correct.

Please help to verify my understanding and the fix.


Looks good to me. Here's a test case you can use to verify your improvement:

--- a/test/test_argument_processing.c
+++ b/test/test_argument_processing.c
@@ -134,6 +134,28 @@ TEST(sysroot_should_be_rewritten_if_basedir_is_used)
  args_free(act_cc);
 }

+TEST(B_option_should_be_rewritten_if_basedir_is_used)
+{
+ extern char *current_working_dir;
+ char *arg_string;
+ struct args *orig;
+ struct args *act_cpp = NULL, *act_cc = NULL;
+
+ create_file("foo.c", "");
+ free(conf->base_dir);
+ conf->base_dir = x_strdup("/");
+ current_working_dir = get_cwd();
+ arg_string = format("cc -B%s/foo -c foo.c", current_working_dir);
+ orig = args_init_from_string(arg_string);
+
+ CHECK(cc_process_args(orig, _cpp, _cc));
+ CHECK_STR_EQ(act_cpp->argv[1], "-B./foo");
+
+ args_free(orig);
+ args_free(act_cpp);
+ args_free(act_cc);
+}
+
 TEST(MF_flag_with_immediate_argument_should_work_as_last_argument)
 {
  struct args *orig = args_init_from_string(


-- Joel
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[ccache] -Bprefix compiler option - resulting in cache miss

[vkr]

Hello,
I believe I found a potential bug with ccache that results in cache-miss if
-Bprfix compilation option is used, where prefix specifies where to find
the executables, libraries, include files, and data files of the compiler
itself.

Example, if my compilation command is:
CCACHE_BASEDIR=$PWD ccache gcc -c hello.c -o hello.o
-B$PWD/linkfarm/sysroot-x86_64_cge7/usr/lib64/4.7.0/


then, from what I understand, ccache is considering this argument
-B$PWD/linkfarm/sysroot-x86_64_cge7/usr/lib64/4.7.0/
as well, while creating the basic-hash for direct cache lookup, but without
rewriting it into its relative path based on CCACHE_BASEDIR setting.
Thus, the hash so generated is for the absolute path of this workspace, and
cannot be reused from another build sandbox.

I verified that the changes done in the fork
https://github.com/venkrao/ccache-1/commit/59e5244dd79b0fc7df682c8f3c05b778a3d00f91
fixes the problem.

To verify that -Bprefix is also put into the hash, with its absolute path,
I put a debug statement on the line
https://github.com/venkrao/ccache-1/blob/59e5244dd79b0fc7df682c8f3c05b778a3d00f91/ccache.c#L1594

Please help to verify my understanding and the fix.

Thanks,
Venkat.
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