https://gcc.gnu.org/g:12992edaa96897d4ce26c3d48fa19c142b0aef28
commit r16-3995-g12992edaa96897d4ce26c3d48fa19c142b0aef28
Author: Alexandre Oliva <ol...@adacore.com>
Date: Fri Sep 19 16:45:19 2025 -0300
[ira] avoid resetting ira_reg_equiv for function invariants
An aarch64 toolchain built with --enable-default-pie fails
gcc.target/aarch64/sme/nonlocal_goto_[123].c because the register
allocator ends up resetting equivalences, so it concludes it needs to
preserve a rematerializable function invariant across a call instead
of rematerializing it.
Restore the find_reg_equiv_invariant_const logic that was in place
before commit 55a2c3226a3e90a6d65f19710bab1ac377054234 rewrote it and
added a (spurious?) requirement for non-function-invariants to retain
an equivalence when other PIC-related conditions didn't apply. That
requirement seems either reversed or unnecessary.
for gcc/ChangeLog
* ira.cc (setup_reg_equiv): Retain function invariant
equivalences.
Diff:
---
gcc/ira.cc | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/ira.cc b/gcc/ira.cc
index 4eebc9c4c50f..3e15966558ed 100644
--- a/gcc/ira.cc
+++ b/gcc/ira.cc
@@ -4233,12 +4233,14 @@ setup_reg_equiv (void)
&& REGNO (SET_SRC (set)) == (unsigned int) i);
x = SET_DEST (set);
}
- if (! function_invariant_p (x)
+ /* If PIC is enabled and the equiv is not a LEGITIMATE_PIC_OPERAND,
+ we can't use it. */
+ if (! CONSTANT_P (x)
|| ! flag_pic
/* A function invariant is often CONSTANT_P but may
include a register. We promise to only pass
CONSTANT_P objects to LEGITIMATE_PIC_OPERAND_P. */
- || (CONSTANT_P (x) && LEGITIMATE_PIC_OPERAND_P (x)))
+ || LEGITIMATE_PIC_OPERAND_P (x))
{
/* It can happen that a REG_EQUIV note contains a MEM
that is not a legitimate memory operand. As later
