Hi,
In this PR we have a situation where we aren't really detecting
weak references vs weak definitions. If one has a weak definition
that binds locally there's no reason not to put out PC relative
relocations.
However if you have a genuine weak reference that is
known not to bind locally it makes very little sense
to put out an entry into the literal pool which doesn't always
work with DSOs and shared objects.
Tested aarch64-none-linux-gnu bootstrap and regression test with no regressions
This is not a regression and given what we've seen recently with protected
symbols and binds_locally_p I'd rather this were queued for GCC 7.
Ok ?
regards
Ramana
gcc/
* config/aarch64/aarch64.c (aarch64_classify_symbol): Typo in comment fixed.
Only force to memory if it is a weak external reference.
gcc/testsuite
* gcc.target/aarch64/pr63874.c: New test.
commit e41d4bd6abbee99628909d4af612504844dee640
Author: Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
Date: Thu Mar 31 13:47:33 2016 +0100
fix PR63874
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index cf1239d..6782316 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -9387,15 +9387,18 @@ aarch64_classify_symbol (rtx x, rtx offset)
switch (aarch64_cmodel)
{
case AARCH64_CMODEL_TINY:
- /* When we retreive symbol + offset address, we have to make sure
+ /* When we retrieve symbol + offset address, we have to make sure
the offset does not cause overflow of the final address. But
we have no way of knowing the address of symbol at compile time
so we can't accurately say if the distance between the PC and
symbol + offset is outside the addressible range of +/-1M in the
TINY code model. So we rely on images not being greater than
1M and cap the offset at 1M and anything beyond 1M will have to
- be loaded using an alternative mechanism. */
- if (SYMBOL_REF_WEAK (x)
+ be loaded using an alternative mechanism. Furthermore if the
+ symbol is a weak reference to something that isn't known to
+ resolve to a symbol in this module, then force to memory. */
+ if ((SYMBOL_REF_WEAK (x)
+ && !aarch64_symbol_binds_local_p (x))
|| INTVAL (offset) < -1048575 || INTVAL (offset) > 1048575)
return SYMBOL_FORCE_TO_MEM;
return SYMBOL_TINY_ABSOLUTE;
@@ -9403,7 +9406,8 @@ aarch64_classify_symbol (rtx x, rtx offset)
case AARCH64_CMODEL_SMALL:
/* Same reasoning as the tiny code model, but the offset cap here is
4G. */
- if (SYMBOL_REF_WEAK (x)
+ if ((SYMBOL_REF_WEAK (x)
+ && !aarch64_symbol_binds_local_p (x))
|| !IN_RANGE (INTVAL (offset), HOST_WIDE_INT_C (-4294967263),
HOST_WIDE_INT_C (4294967264)))
return SYMBOL_FORCE_TO_MEM;
diff --git a/gcc/testsuite/gcc.target/aarch64/pr63874.c
b/gcc/testsuite/gcc.target/aarch64/pr63874.c
new file mode 100644
index 0000000..1a745a0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr63874.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-skip-if "Not applicable for mcmodel=large" { aarch64*-*-* } {
"-mcmodel=large" } { "" } } */
+
+extern void __attribute__((weak)) foo_weakref (void);
+void __attribute__((weak, noinline)) bar (void)
+{
+ return;
+}
+void (*f) (void);
+void (*g) (void);
+
+int
+main (void)
+{
+ f = &foo_weakref;
+ g = &bar;
+ return 0;
+}
+
+/* { dg-final { scan-assembler-not "adr*foo_weakref" } } */
+/* { dg-final { scan-assembler-not "\\.(word|xword)\tbar" } } */
