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cdb6b19b5f
Fixes <https://issues.guix.gnu.org/55616>.
Reported by Tim Rakowski <tim.rakowski@gmail.com>.
This is a followup to 37e29ccd33.
* gnu/packages/patches/gcc-12-strmov-store-file-names.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
114 lines
3.5 KiB
Diff
114 lines
3.5 KiB
Diff
Make sure that statements such as:
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strcpy (dst, "/gnu/store/…");
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or
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static const char str[] = "/gnu/store/…";
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…
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strcpy (dst, str);
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do not result in chunked /gnu/store strings that are undetectable by
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Guix's GC and its grafting code. See <https://bugs.gnu.org/24703>
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and <https://bugs.gnu.org/30395>.
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diff --git a/gcc/builtins.cc b/gcc/builtins.cc
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index 5b085e3a1..480bc0b54 100644
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--- a/gcc/builtins.cc
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+++ b/gcc/builtins.cc
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@@ -3363,6 +3363,58 @@ expand_builtin_mempcpy (tree exp, rtx target)
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target, exp, /*retmode=*/ RETURN_END);
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}
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+extern void debug_tree (tree);
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+
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+/* Return true if STR contains the string "/gnu/store". */
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+
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+bool
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+store_reference_p (tree str)
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+{
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+ if (getenv ("GUIX_GCC_DEBUG") != NULL)
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+ debug_tree (str);
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+
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+ if (TREE_CODE (str) == ADDR_EXPR)
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+ str = TREE_OPERAND (str, 0);
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+
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+ if (TREE_CODE (str) == VAR_DECL
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+ && TREE_STATIC (str)
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+ && TREE_READONLY (str))
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+ {
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+ /* STR may be a 'static const' variable whose initial value
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+ is a string constant. See <https://bugs.gnu.org/30395>. */
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+ str = DECL_INITIAL (str);
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+ if (str == NULL_TREE)
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+ return false;
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+ }
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+
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+ if (TREE_CODE (str) != STRING_CST)
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+ return false;
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+
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+ int len;
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+ const char *store;
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+
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+ store = getenv ("NIX_STORE") ? getenv ("NIX_STORE") : "/gnu/store";
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+ len = strlen (store);
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+
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+ /* Size of the hash part of store file names, including leading slash and
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+ trailing hyphen. */
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+ const int hash_len = 34;
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+
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+ if (TREE_STRING_LENGTH (str) < len + hash_len)
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+ return false;
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+
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+ /* We cannot use 'strstr' because 'TREE_STRING_POINTER' returns a string
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+ that is not necessarily NUL-terminated. */
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+
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+ for (int i = 0; i < TREE_STRING_LENGTH (str) - (len + hash_len); i++)
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+ {
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+ if (strncmp (TREE_STRING_POINTER (str) + i, store, len) == 0)
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+ return true;
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+ }
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+
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+ return false;
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+}
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+
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/* Helper function to do the actual work for expand of memory copy family
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functions (memcpy, mempcpy, stpcpy). Expansing should assign LEN bytes
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of memory from SRC to DEST and assign to TARGET if convenient. Return
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@@ -3384,6 +3436,13 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len,
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bool is_move_done;
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+ /* Do not emit block moves, which translate to the 'movabs' instruction on
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+ x86_64, when SRC refers to store items. That way, store references
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+ remain visible to the Guix GC and grafting code. See
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+ <https://bugs.gnu.org/24703>. */
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+ if (store_reference_p (src))
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+ return NULL_RTX;
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+
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/* If DEST is not a pointer type, call the normal function. */
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if (dest_align == 0)
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return NULL_RTX;
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diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
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index 863ee3d39..4cc46c265 100644
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--- a/gcc/gimple-fold.cc
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+++ b/gcc/gimple-fold.cc
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@@ -856,6 +856,8 @@ var_decl_component_p (tree var)
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&& TREE_CODE (TREE_OPERAND (inner, 0)) == ADDR_EXPR));
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}
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+extern bool store_reference_p (tree);
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+
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/* Return TRUE if the SIZE argument, representing the size of an
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object, is in a range of values of which exactly zero is valid. */
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@@ -960,6 +962,9 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
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= build_int_cst (build_pointer_type_for_mode (char_type_node,
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ptr_mode, true), 0);
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+ if (store_reference_p (src))
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+ return false;
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+
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/* If we can perform the copy efficiently with first doing all loads
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and then all stores inline it that way. Currently efficiently
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means that we can load all the memory into a single integer
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