On 12/28/2015 02:54 PM, Sergei Trofimovich wrote:
From: Sergei Trofimovich <siarh...@google.com>
Tested on the following example:
void * a[77] __attribute((visibility("hidden")));
void f(long o, void * v) { a[0x6ffffeff - o + 66] = v; }
Before the patch generated code uses .GOT entry:
addl r14 = @ltoffx(a#), r1
ld8.mov r14 = [r14], a#
After the patch generated code uses static gprel relocation:
movl r14 = @gprel(a#)
add r14 = r1, r14
That way gcc will be able to compile glibc's ld: PR/60465
Egad. PIC on ia64 is a mess. I can kind of see what Richard was trying
to do, but ewww. I don't think it's worth the effort to deep dive into
the PIC support and make ia64 handle things like most other ports --
it's a dead architecture so ISTM the easiest fix is the right fix.
A few, relatively minor things.
Bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60465
Signed-off-by: Sergei Trofimovich <siarh...@google.com>
---
gcc/config/ia64/ia64.c | 2 ++
gcc/config/ia64/predicates.md | 26 ++++++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/gcc/config/ia64/ia64.c b/gcc/config/ia64/ia64.c
index f48cebc..6ea5072 100644
--- a/gcc/config/ia64/ia64.c
+++ b/gcc/config/ia64/ia64.c
@@ -1105,6 +1105,8 @@ ia64_expand_load_address (rtx dest, rtx src)
emit_insn (gen_load_fptr (dest, src));
else if (sdata_symbolic_operand (src, VOIDmode))
emit_insn (gen_load_gprel (dest, src));
+ else if (local_symbolic_operand64 (src, VOIDmode))
+ emit_insn (gen_load_gprel64 (dest, src));
Comment here. Something like
/* We want to use gprel rather than ltoff relocations for
local symbolic operands. */
+;; True if OP refers to a local symbol +any large offset).
;; True if OP refers to a local symbol [+ any offset ]
I haven't dug into the ia64 port (and I'm not planning to) to see if/how
it MINUS in symbolic expressions. It's been the source of problems in
various ports trough the years.
Can you take the testcase from your post as well as the one from BZ60465
comment #37 (from you) and add them to the testsuite?
You can dump them into testsuite/gcc.target/ia64.
I think you'll just want to scan the assembler output to verify you're
not getting ltoff relocations. Look for uses of scan-assembler-not in
other tests for examples.
Normally we'd require a bootstrap & regression test. We're more lenient
with patches to dead architectures. What I'd do is something like
Add new tests to <path_to_sources/gcc/testsuite/gcc.target/ia64/
<path_to_sources>/configure <any flags you wanted>
make <-j whatever> all-gcc
cd gcc
make check-gcc RUNTESTFLAGS=ia64.exp
Save those results. Ideally everything will pass except your two new tests.
Apply your patch to ia64.c/predicates.md then just
make <-j whatever> all-gcc
cd gcc
make check-gcc RUNTESTFLAGS=ia64.exp
Note you're not running the full testsuite, just a few dozen ia64
specific tests, which will include your new tests. ANd you're not
rebuilding the whole compiler between those steps, just ia64.o and
relinking the compiler. So it ought to be reasonably fast.
So to summarize, I think your patch needs the two trivial comment fixes
noted above, 2 testcases and the before/after results of running just
the ia64.exp tests. Repost with that and I'll get it into the tree.
Jeff
