Make sure that statements such as: strcpy (dst, "/gnu/store/…"); or static const char str[] = "/gnu/store/…"; … strcpy (dst, str); do not result in chunked /gnu/store strings that are undetectable by Guix's GC and its grafting code. See and . --- gcc-5.3.0/gcc/builtins.c 2016-10-18 10:50:46.080616285 +0200 +++ gcc-5.3.0/gcc/builtins.c 2016-11-09 15:26:43.693042737 +0100 @@ -3192,6 +3192,58 @@ determine_block_size (tree len, rtx len_ GET_MODE_MASK (GET_MODE (len_rtx))); } +extern void debug_tree (tree); + +/* Return true if STR contains the string "/gnu/store". */ + +bool +store_reference_p (tree str) +{ + if (getenv ("GUIX_GCC_DEBUG") != NULL) + debug_tree (str); + + if (TREE_CODE (str) == ADDR_EXPR) + str = TREE_OPERAND (str, 0); + + if (TREE_CODE (str) == VAR_DECL + && TREE_STATIC (str) + && TREE_READONLY (str)) + { + /* STR may be a 'static const' variable whose initial value + is a string constant. See . */ + str = DECL_INITIAL (str); + if (str == NULL_TREE) + return false; + } + + if (TREE_CODE (str) != STRING_CST) + return false; + + int len; + const char *store; + + store = getenv ("NIX_STORE") ? getenv ("NIX_STORE") : "/gnu/store"; + len = strlen (store); + + /* Size of the hash part of store file names, including leading slash and + trailing hyphen. */ + const int hash_len = 34; + + if (TREE_STRING_LENGTH (str) < len + hash_len) + return false; + + /* We cannot use 'strstr' because 'TREE_STRING_POINTER' returns a string + that is not necessarily NUL-terminated. */ + + for (int i = 0; i < TREE_STRING_LENGTH (str) - (len + hash_len); i++) + { + if (strncmp (TREE_STRING_POINTER (str) + i, store, len) == 0) + return true; + } + + return false; +} + /* Helper function to do the actual work for expand_builtin_memcpy. */ static rtx @@ -3207,6 +3243,13 @@ expand_builtin_memcpy_args (tree dest, t unsigned HOST_WIDE_INT max_size; unsigned HOST_WIDE_INT probable_max_size; + /* Do not emit block moves, which translate to the 'movabs' instruction on + x86_64, when SRC refers to store items. That way, store references + remain visible to the Guix GC and grafting code. See + . */ + if (store_reference_p (src)) + return NULL_RTX; + /* If DEST is not a pointer type, call the normal function. */ if (dest_align == 0) return NULL_RTX; --- gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:36:16.709442004 +0100 +++ gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:46:43.838487065 +0100 @@ -769,6 +769,8 @@ var_decl_component_p (tree var) return SSA_VAR_P (inner); } +extern bool store_reference_p (tree); + /* Fold function call to builtin mem{{,p}cpy,move}. Return false if no simplification can be made. If ENDP is 0, return DEST (like memcpy). @@ -1099,6 +1101,9 @@ gimple_fold_builtin_memory_op (gimple_st if (!srctype) return false; + if (store_reference_p (src)) + return false; + src_align = get_pointer_alignment (src); dest_align = get_pointer_alignment (dest); if (dest_align < TYPE_ALIGN (desttype) (Running Guix Before It Is Installed): Remove footnote about abusing ~/.config/guix/latest. Ludovic Courtès 2018-01-28guix: Let Emacs detect “scripts/guix.in” appropriate mode....Since commit 6f774d481839f87178c5895ac2d661e141f879b8 which introduces the use of Guile's meta switch in “scripts/guix.in”, Emacs was not using ‘scheme-mode’ for this file. * scripts/guix.in: Replace "-*- scheme -*-" with a local variable. Signed-off-by: Ludovic Courtès <ludo@gnu.org> Mathieu Lirzin 2018-01-23guix: Refactor script....* scripts/guix.in: Remove empty surrounding ‘let’. Define 'main' as the procedure called when running the script. (maybe-augment-load-paths!): Rename to ... (augment-load-paths!): ... this. Use 'and=>' for 'file-exists?'. (run-guix-main): Rename to ... (main): ... this. Call 'augment-load-paths!'. Signed-off-by: Ludovic Courtès <ludo@gnu.org> Mathieu Lirzin 2018-01-23build: Expand ‘scripts/guix’ at Make time....This moves the complexity of Autotools variable expansion outside of the application code. * scripts/guix.in (config-lookup): Delete. (maybe-augment-load-paths!, run-guix-main): Use fully expanded variables instead of calling ‘config-lookup’. * configure.ac: Don't use AC_CONFIG_FILES for ‘scripts/guix’. Use AC_PROG_SED. * Makefile.am (scripts/guix): New rule. (do_subst): New variable. (CLEANFILES, EXTRA_DIST): Adapt. Co-authored-by: Ludovic Courtès <ludo@gnu.org> Mathieu Lirzin 2017-03-20build: Install .go files to $libdir/guile/X.Y....* configure.ac: Define and substitute 'guileobjectdir'. * Makefile.am (nobase_nodist_guilemodule_DATA): Remove $(GOBJECTS). (nobase_nodist_guileobject_DATA): New variable. (guix_install_go_files): Adjust accordingly. (install-data-hook): Likewise. * scripts/guix.in (config-lookup): Add 'exec_prefix' and 'guileobjectdir'. Add '_' in VAR-REF-REGEXP. (maybe-augment-load-paths!): Distinguish OBJECT-DIR from MODULE-DIR. Ludovic Courtès