Tested on a cross to powerpc-darwin9 and on aarch64-darwin21,
pushed to trunk,
thanks
Iain
--- 8< ---
When we are using section anchors, there's a requirement that the
sequence of the content is an unbroken block. If we allow linker-
visible symbols in that block, ld(64) would be able to break it
into sub-sections on those symbol boundaries.
Do not allow symbols that should be visible to be anchored.
Do not make anchor block internal symbols linker-visible.
gcc/ChangeLog:
* config/darwin.cc (darwin_encode_section_info): Do not
make anchored symbols linker-visible.
(darwin_use_anchors_for_symbol_p): Disallow anchoring on
symbols that must be linker-visible (or external), even
if the definitions are in this TU.
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
---
gcc/config/darwin.cc | 38 +++++++++++++++++++++++++++++++++-----
1 file changed, 33 insertions(+), 5 deletions(-)
diff --git a/gcc/config/darwin.cc b/gcc/config/darwin.cc
index be2daed4f66..1724084b628 100644
--- a/gcc/config/darwin.cc
+++ b/gcc/config/darwin.cc
@@ -1298,6 +1298,29 @@ darwin_encode_section_info (tree decl, rtx rtl, int
first)
SYMBOL_FLAG_EXTERNAL. */
default_encode_section_info (decl, rtl, first);
+ if (CONSTANT_CLASS_P (decl))
+ {
+ bool is_str = TREE_CODE (decl) == STRING_CST;
+ rtx sym_ref = XEXP (rtl, 0);
+
+ /* If this is a string cst or not anchored we have nothing to do. */
+ if (is_str || !SYMBOL_REF_HAS_BLOCK_INFO_P (sym_ref))
+ return;
+
+ tree sym_decl = SYMBOL_REF_DECL (sym_ref);
+ const char *name = XSTR (sym_ref, 0);
+ gcc_checking_assert (strncmp ("*lC", name, 3) == 0);
+
+ char *buf;
+ /* Lets identify anchored constants with a different prefix, for the
+ sake of inspection only. */
+ buf = xasprintf ("*LaC%s", &name[3]);
+ if (sym_decl)
+ DECL_NAME (sym_decl) = get_identifier (buf);
+ XSTR (sym_ref, 0) = ggc_strdup (buf);
+ free (buf);
+ }
+
if (! VAR_OR_FUNCTION_DECL_P (decl))
return;
@@ -3297,11 +3320,16 @@ darwin_use_anchors_for_symbol_p (const_rtx symbol)
{
if (DARWIN_SECTION_ANCHORS && flag_section_anchors)
{
- section *sect;
- /* If the section contains a zero-sized object it's ineligible. */
- sect = SYMBOL_REF_BLOCK (symbol)->sect;
- /* This should have the effect of disabling anchors for vars that follow
- any zero-sized one, in a given section. */
+ tree decl = SYMBOL_REF_DECL (symbol);
+ /* If the symbol would be linker-visible, then it can split at that
+ so we must disallow. This is more strict than the default impl.
+ TODO: add other cases. */
+ if (decl && DECL_P (decl)
+ && (TREE_PUBLIC (decl) || !DECL_ARTIFICIAL (decl)))
+ return false;
+
+ /* We mark sections containing unsuitable entries. */
+ section *sect = SYMBOL_REF_BLOCK (symbol)->sect;
if (sect->common.flags & SECTION_NO_ANCHOR)
return false;
--
2.39.2 (Apple Git-143)
