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aarch64: Validate register operands early in ldp fusion pass [PR113062]

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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.
This commit is contained in:
Alex Coplan 2023-12-20 09:39:29 +00:00
parent bfdadcb299
commit f5213759a7
2 changed files with 18 additions and 3 deletions
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11
gcc/config/aarch64/aarch64-ldp-fusion.cc
View file

@ -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))

10
gcc/testsuite/gcc.dg/pr113062.c Normal file
View file

@ -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();
}