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| author | Jakub Jelinek <jakub@redhat.com> | 2023-12-06 09:55:30 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2023-12-06 09:55:30 +0100 |
| commit | 0ca64f846edce3c7b7f26bcc5978118e560e65b1 (patch) | |
| tree | e868a114a40368fc342c4a23531086e6bfbf48e4 /gcc | |
| parent | 895a70f012b8c1b8e80ecc584c1d7ded014bc2bc (diff) | |
| download | gcc-0ca64f846edce3c7b7f26bcc5978118e560e65b1.zip gcc-0ca64f846edce3c7b7f26bcc5978118e560e65b1.tar.gz gcc-0ca64f846edce3c7b7f26bcc5978118e560e65b1.tar.bz2 | |
lower-bitint: Fix arithmetics followed by extension by many bits [PR112809]
A zero or sign extension from result of some upwards_2limb operation
is implemented in lower_mergeable_stmt as an extra loop which fills in
the extra bits with 0s or 1s.
If the delta of extended vs. unextended bit count is small, the code
doesn't use a loop and emits up to a couple of stores to constant indexes,
but if the delta is large, it uses
cnt = (bo_bit != 0) + 1 + (rem != 0);
statements. bo_bit is non-zero for bit-field loads and is done in that
case as straight line, the unconditional 1 in there is for a loop which
handles most of the limbs in the delta and finally (rem != 0) is for the
case when the extended precision is not a multiple of limb_prec and is
again done in straight line code (after the loop).
The testcase ICEs because the decision what idx to use was incorrect
for kind == bitint_prec_huge (i.e. when the precision delta is very large)
and rem == 0 (i.e. the extended precision is multiple of limb_prec).
In that case cnt is either 1 (if bo_bit == 0) or 2, and idx should
be either first size_int (start) and then result of create_loop (for bo_bit
!= 0) or just result of create_loop, but by mistake the last case
was size_int (end), which means when precision is multiple of limb_prec
storing above the precision (which ICEs; but also not emitting the loop
which is needed).
2023-12-06 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/112809
* gimple-lower-bitint.cc (bitint_large_huge::lower_mergeable_stmt): For
separate_ext in kind == bitint_prec_huge mode if rem == 0, create for
i == cnt - 1 the loop rather than using size_int (end).
* gcc.dg/bitint-48.c: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/gimple-lower-bitint.cc | 2 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/bitint-48.c | 23 |
2 files changed, 24 insertions, 1 deletions
diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc index 575883a..d2026f6 100644 --- a/gcc/gimple-lower-bitint.cc +++ b/gcc/gimple-lower-bitint.cc @@ -2624,7 +2624,7 @@ bitint_large_huge::lower_mergeable_stmt (gimple *stmt, tree_code &cmp_code, { if (kind == bitint_prec_large || (i == 0 && bo_bit != 0)) idx = size_int (start + i); - else if (i == cnt - 1) + else if (i == cnt - 1 && (rem != 0)) idx = size_int (end); else if (i == (bo_bit != 0)) idx = create_loop (size_int (start + i), &idx_next); diff --git a/gcc/testsuite/gcc.dg/bitint-48.c b/gcc/testsuite/gcc.dg/bitint-48.c new file mode 100644 index 0000000..8701ebb --- /dev/null +++ b/gcc/testsuite/gcc.dg/bitint-48.c @@ -0,0 +1,23 @@ +/* PR tree-optimization/112809 */ +/* { dg-do compile { target bitint } } */ +/* { dg-options "-O2" } */ + +#if __BITINT_MAXWIDTH__ >= 512 +_BitInt (512) a; +_BitInt (256) b; +_BitInt (256) c; + +int +foo (void) +{ + return a == (b | c); +} + +void +bar (void) +{ + a /= b - 2; +} +#else +int i; +#endif |