Package: gcc-5
Version: 5.3.1-12
Severity: wishlist
Tags: patch
User: reproducible-bui...@lists.alioth.debian.org
Usertags: buildpath
embedding the build path in binaries makes it harder to get
byte-for-byte reproducibility, because the build has to happen in the
same directory.
gcc by default embeds the build path in the debug info of C tools
(e.g. DW_AT_comp_dir and DW_AT_decl_file). This isn't useful for
distributed binary packages, because the build environment isn't on
the same machine (or necessarily in the same place).
The build path can be mangled/stripped with gcc's -fdebug-prefix-map
argument. For example:
gcc -fdebug-prefix-map=$(pwd)=. -g -o foo foo.c
however, when supplying -fdebug-prefix-map, gcc puts that string
itself into DW_AT_producer.
The attached patch (pulled from upstream gcc master) avoids storing
-fdebug-prefix-map in DW_AT_producer.
I'd like this to be backported into debian's gcc so that we can make
and test a more reproducible toolchain.
(thinking about timing: we shouldn't need the patch once we move to
gcc 6, but we should be testing a buildpath-independent reproducible
toolchain now; i'll file a bug soon to add this pattern to either dh
or dpkg-buildflags)
Regards,
--dkg
-- System Information:
Debian Release: stretch/sid
Architecture: amd64 (x86_64)
Kernel: Linux 4.4.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages gcc-5 depends on:
ii binutils 2.26-5
ii cpp-5 5.3.1-12
ii gcc-5-base 5.3.1-12
ii libc6 2.22-3
ii libcc1-0 5.3.1-12
ii libgcc-5-dev 5.3.1-12
ii libgcc1 1:5.3.1-12
ii libgmp10 2:6.1.0+dfsg-2
ii libisl15 0.16.1-1
ii libmpc3 1.0.3-1
ii libmpfr4 3.1.4-1
ii libstdc++6 5.3.1-12
ii zlib1g 1:1.2.8.dfsg-2+b1
Versions of packages gcc-5 recommends:
ii libc6-dev 2.22-3
Versions of packages gcc-5 suggests:
pn gcc-5-doc <none>
pn gcc-5-locales <none>
ii gcc-5-multilib 5.3.1-12
pn libasan2-dbg <none>
pn libatomic1-dbg <none>
pn libcilkrts5-dbg <none>
pn libgcc1-dbg <none>
pn libgomp1-dbg <none>
pn libitm1-dbg <none>
pn liblsan0-dbg <none>
pn libmpx0-dbg <none>
pn libquadmath0-dbg <none>
pn libtsan0-dbg <none>
pn libubsan0-dbg <none>
-- debconf-show failed
>From 6ceddcd7b87911ddbb942923722af5a735dacedc Mon Sep 17 00:00:00 2001
From: bernds <bernds@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 18 Dec 2015 19:48:26 +0000
Subject: [PATCH] Ignore -fdebug-prefix-map in producer string (by Daniel Kahn
Gillmor)
* dwarf2out.c (gen_producer_string): Ignore -fdebug-prefix-map.
testsuite/
* gcc.dg/debug/dwarf2/prod-options.c: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@231835 138bc75d-0d04-0410-961f-82ee72b054a4
---
gcc/ChangeLog | 4 ++++
gcc/dwarf2out.c | 1 +
gcc/testsuite/ChangeLog | 4 ++++
gcc/testsuite/gcc.dg/debug/dwarf2/prod-options.c | 12 ++++++++++++
4 files changed, 21 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/debug/dwarf2/prod-options.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fec7992..11ee620 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2015-12-18 Daniel Kahn Gillmor <d...@fifthhorseman.net>
+
+ * dwarf2out.c (gen_producer_string): Ignore -fdebug-prefix-map.
+
2015-12-18 Nathan Sidwell <nat...@acm.org>
* config/nvptx/nvptx.c (nvptx_option_override): Emit sorry for
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 067c4f2..320a077 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -21498,6 +21498,7 @@ gen_producer_string (void)
case OPT_fpreprocessed:
case OPT_fltrans_output_list_:
case OPT_fresolution_:
+ case OPT_fdebug_prefix_map_:
/* Ignore these. */
continue;
default:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5da1ce4..b2d9d3b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-12-18 Bernd Schmidt <bschm...@redhat.com>
+
+ * gcc.dg/debug/dwarf2/prod-options.c: New test.
+
2015-12-18 Eric Botcazou <ebotca...@adacore.com>
* gnat.dg/specs/debug1.ads: Bump final count to 18.
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/prod-options.c b/gcc/testsuite/gcc.dg/debug/dwarf2/prod-options.c
new file mode 100644
index 0000000..21449f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/prod-options.c
@@ -0,0 +1,12 @@
+/* Verify that the DW_AT_producer does not contain certain compiler options
+ such as -fdebug-prefix-map=; this is undesirable since path names make
+ the build not reproducible. Other skipped options could be tested here
+ as well. */
+/* { dg-do compile } */
+/* { dg-options "-O2 -gdwarf -dA -fdebug-prefix-map=a=b" } */
+/* { dg-final { scan-assembler "DW_AT_producer: \"GNU C" } } */
+/* { dg-final { scan-assembler-not "debug-prefix-map" } } */
+
+void func (void)
+{
+}
--
2.8.0.rc3
