On 3/4/24 09:49, Jakub Jelinek wrote:
On Mon, Mar 04, 2024 at 05:18:39PM +0100, Rainer Orth wrote:
On 2/26/24 17:17, Greg McGary wrote:
The sign-bit-copies of a sign-extending load cannot be known until runtime on
WORD_REGISTER_OPERATIONS targets, except in the case of a zero-extending MEM
load. See the fix for PR112758.
2024-02-22 Greg McGary <g...@rivosinc.com>
PR rtl-optimization/113010
* combine.cc (simplify_comparison): Simplify a SUBREG on
WORD_REGISTER_OPERATIONS targets only if it is a zero-extending
MEM load.
* gcc.c-torture/execute/pr113010.c: New test.
I think this is fine for the trunk. I'll do some final testing on it
tomorrow.
unfortunately, the patch broke Solaris/SPARC bootstrap
(sparc-sun-solaris2.11):
/vol/gcc/src/hg/master/local/gcc/combine.cc: In function 'rtx_code
simplify_comparison(rtx_code, rtx_def**, rtx_def**)':
/vol/gcc/src/hg/master/local/gcc/combine.cc:12101:25: error: '*(unsigned
int*)((char*)&inner_mode + offsetof(scalar_int_mode, scalar_int_mode::m_mode))'
may be used uninitialized [-Werror=maybe-uninitialized]
12101 | scalar_int_mode mode, inner_mode, tmode;
| ^~~~~~~~~~
I don't see how it could ever work properly, inner_mode in that spot is
just uninitialized.
I think we shouldn't worry about paradoxical subregs of non-scalar_int_mode
REGs/MEMs and for the scalar_int_mode ones should initialize inner_mode
before we use it.
Another option would be to use
maybe_lt (GET_MODE_PRECISION (GET_MODE (SUBREG_REG (op0))), BITS_PER_WORD)
and
load_extend_op (GET_MODE (SUBREG_REG (op0))) == ZERO_EXTEND,
or set machine_mode smode = GET_MODE (SUBREG_REG (op0)); and use it in
those two spots.
2024-03-04 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/113010
* combine.cc (simplify_comparison): Guard the
WORD_REGISTER_OPERATIONS check on scalar_int_mode of SUBREG_REG
and initialize inner_mode.
Egad. Sorry. OK for the trunk. Thanks for picking this up. Got
distracted by an internal issue.
jeff
