This is a v2 addressing Richard's feedback, v1 was posted here:
https://gcc.gnu.org/pipermail/gcc-patches/2023-December/640957.html
Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?
Thanks,
Alex
-- >8 --
We were missing validation of the candidate register operands in the
ldp/stp pass. I was relying on recog rejecting such cases when we
formed the final pair insn, but the testcase shows that with
-fharden-conditionals we attempt to combine two insns with asm_operands,
both containing mem rtxes. This then trips the assert:
gcc_assert (change->new_uses.is_valid ());
in the stp case as we aren't expecting to have (distinct) uses of mem in
the candidate stores.
While doing this I noticed that it seems more natural to have the
initial definition of mem_size closer to its first use in track_access,
so I moved that down.
gcc/ChangeLog:
PR target/113062
* config/aarch64/aarch64-ldp-fusion.cc
(ldp_bb_info::track_access): Punt on accesses with invalid
register operands, move definition of mem_size closer to its
first use.
gcc/testsuite/ChangeLog:
PR target/113062
* gcc.dg/pr113062.c: New test.
diff --git a/gcc/config/aarch64/aarch64-ldp-fusion.cc
b/gcc/config/aarch64/aarch64-ldp-fusion.cc
index 327ba4e417d..0e2c299a0bf 100644
--- a/gcc/config/aarch64/aarch64-ldp-fusion.cc
+++ b/gcc/config/aarch64/aarch64-ldp-fusion.cc
@@ -458,11 +458,14 @@ ldp_bb_info::track_access (insn_info *insn, bool load_p,
rtx mem)
if (!ldp_operand_mode_ok_p (mem_mode))
return;
- // Note ldp_operand_mode_ok_p already rejected VL modes.
- const HOST_WIDE_INT mem_size = GET_MODE_SIZE (mem_mode).to_constant ();
-
rtx reg_op = XEXP (PATTERN (insn->rtl ()), !load_p);
+ // Ignore the access if the register operand isn't suitable for ldp/stp.
+ if (load_p
+ ? !aarch64_ldp_reg_operand (reg_op, mem_mode)
+ : !aarch64_stp_reg_operand (reg_op, mem_mode))
+ return;
+
// We want to segregate FP/SIMD accesses from GPR accesses.
//
// Before RA, we use the modes, noting that stores of constant zero
@@ -474,6 +477,8 @@ ldp_bb_info::track_access (insn_info *insn, bool load_p,
rtx mem)
: (GET_MODE_CLASS (mem_mode) != MODE_INT
&& (load_p || !aarch64_const_zero_rtx_p (reg_op)));
+ // Note ldp_operand_mode_ok_p already rejected VL modes.
+ const HOST_WIDE_INT mem_size = GET_MODE_SIZE (mem_mode).to_constant ();
const lfs_fields lfs = { load_p, fpsimd_op_p, mem_size };
if (track_via_mem_expr (insn, mem, lfs))
diff --git a/gcc/testsuite/gcc.dg/pr113062.c b/gcc/testsuite/gcc.dg/pr113062.c
new file mode 100644
index 00000000000..5667c17b0f6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr113062.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-Oz -fharden-conditional-branches" } */
+long double foo;
+double bar;
+void abort();
+void check() {
+ if (foo == bar)
+ abort();
+}
+
