When creating a linker mapfile (using -Map=MAPFILE), we previously would
always try to evaluate the expression from a PROVIDE statement.
However, this is not always safe, consider:
PROVIDE (foo = 0x10);
PROVIDE (bar = foo);
In this example, if neither 'foo' or 'bar' is needed, then while
generating the linker mapfile evaluating the expression for 'foo' is
harmless (just the value 0x10). However, evaluating the expression for
'bar' requires the symbol 'foo', which is undefined. This used to cause
a fatal error.
This patch changes the behaviour, so that when the destination of the
PROVIDE is not defined (that is the PROVIDE is not going to provide
anything) the expression is not evaluated, and instead a special string
is displayed to indicate that the linker is discarding the PROVIDE
statement.
This change not only fixes the spurious undefined symbol error, but also
means that a user can now tell if a PROVIDE statement has provided
anything by inspecting the linker mapfile, something that could not be
done before.
ld/ChangeLog:
* ldlang.c (print_assignment): Only evaluate the expression for a
PROVIDE'd assignment when the destination is being defined.
Display a special message for PROVIDE'd symbols that are not being
provided.
ld/testsuite/ChangeLog:
* ld-scripts/provide-4.d: New file.
* ld-scripts/provide-4-map.d: New file.
* ld-scripts/provide-4.t: New file.
* ld-scripts/provide-5.d: New file.
* ld-scripts/provide-5.s: New file.
* ld-scripts/provide-5-map.d: New file.
* ld-scripts/provide-5.t: New file.
* ld-scripts/provide.exp: Run the provide-4.d and provide-5.d
tests.
* ldlang.c (entry_symbol_default): New file-scope global.
(lang_finish): Use it, not a hardwired "start".
(lang_default_entry): Set it.
* ldlang.h: Declare lang_default_entry.
* emultempl/beos.em, emultempl/pe.em: Use lang_default_entry,
not lang_add_entry, to override default entry point symbol.
ld/testsuite:
* ld-scripts/align.exp: Mark align1 XFAIL on PECOFF targets.
* ld-scripts/data.exp: Mark data UNSUPPORTED on a.out targets.
* ld-scripts/provide.exp, ld-scripts/size.exp: Mark all tests
UNSUPPORTED on a.out targets. Tidy.
* ld-scripts/assert.s: Remove comment.
* ld-scripts/data.s: Likewise.
* ld-scripts/data.t: Set start address to allow for aout headers.
Make first LONG pc-relative.
* ld-scripts/data.d: Update.
* ld-scripts/defined2.d: Allow other random syms.
* ld-scripts/defined3.d: Likewise.
* ld-scripts/provide-1.s: Pad section.
* ld-scripts/provide-1.t: Set .data address and align.
* ld-scripts/provide-1.d: Update.
* ld-scripts/provide-2.s: Pad section.
* ld-scripts/provide-2.d: Allow random trailing syms.
* ld-scripts/provide-3.s: Pad section.
* ld-scripts/provide-3.d: Fix typos.
* ld-scripts/provide.exp: Don't run on aix.
* ld-scripts/size-1.s: Simplify test.
* ld-scripts/size-1.t: Rewrite.
* ld-scripts/size-1.d: Update.
* ld-scripts/size-2.s: Simplify.
* ld-scripts/size-2.t: Set start address. Set exe flag on image.
* ld-scripts/size-2.d: Update.
* ld-scripts/size.exp: Don't run on aix. Run size-2 on all elf
targets except mips.
