diff options
| author | Jakub Jelinek <jakub@redhat.com> | 2021-06-24 12:24:48 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-06-24 12:24:48 +0200 |
| commit | 9872bd8c35be0f4d475fac739115cf5b82cdabc0 (patch) | |
| tree | ccf9f8ec9fab3fc57077c6b23da5dcbaeca6cfe8 /gcc/df-scan.c | |
| parent | 65371066d8967560e3508af4a804e0ddb90acee7 (diff) | |
| download | gcc-9872bd8c35be0f4d475fac739115cf5b82cdabc0.zip gcc-9872bd8c35be0f4d475fac739115cf5b82cdabc0.tar.gz gcc-9872bd8c35be0f4d475fac739115cf5b82cdabc0.tar.bz2 | |
df: Fix up handling of paradoxical subregs in debug insns [PR101170]
The recent addition of gcc_assert (regno < endregno); triggers during
glibc build on m68k.
The problem is that RA decisions shouldn't depend on expressions in
DEBUG_INSNs and those expressions can contain paradoxical subregs of certain
pseudos. If RA then decides to allocate the pseudo to a register
with very small hard register REGNO, we can trigger the new assert,
as (int) subreg_regno_offset may be negative on big endian and the small
REGNO + the negative offset can wrap around.
The following patch in that case records the range from the REGNO 0 to
endregno, before the addition of the assert as both regno and endregno are
unsigned it wouldn't record anything at all silently.
2021-06-24 Jakub Jelinek <jakub@redhat.com>
PR middle-end/101170
* df-scan.c (df_ref_record): For paradoxical big-endian SUBREGs
where regno + subreg_regno_offset wraps around use 0 as starting
regno.
* gcc.dg/pr101170.c: New test.
Diffstat (limited to 'gcc/df-scan.c')
| -rw-r--r-- | gcc/df-scan.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/gcc/df-scan.c b/gcc/df-scan.c index e9da64f..3dbda7a 100644 --- a/gcc/df-scan.c +++ b/gcc/df-scan.c @@ -2576,9 +2576,21 @@ df_ref_record (enum df_ref_class cl, if (GET_CODE (reg) == SUBREG) { - regno += subreg_regno_offset (regno, GET_MODE (SUBREG_REG (reg)), - SUBREG_BYTE (reg), GET_MODE (reg)); - endregno = regno + subreg_nregs (reg); + int off = subreg_regno_offset (regno, GET_MODE (SUBREG_REG (reg)), + SUBREG_BYTE (reg), GET_MODE (reg)); + unsigned int nregno = regno + off; + endregno = nregno + subreg_nregs (reg); + if (off < 0 && regno < (unsigned) -off) + /* Deal with paradoxical SUBREGs on big endian where + in debug insns the hard reg number might be smaller + than -off, such as (subreg:DI (reg:SI 0 [+4 ]) 0)); + RA decisions shouldn't be affected by debug insns + and so RA can decide to put pseudo into a hard reg + with small REGNO, even when it is referenced in + a paradoxical SUBREG in a debug insn. */ + regno = 0; + else + regno = nregno; } else endregno = END_REGNO (reg); |