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| author | Jakub Jelinek <jakub@redhat.com> | 2023-03-02 09:27:40 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2023-03-19 06:28:53 +0100 |
| commit | 726682897d877afacb8164130cbbc715f8b44784 (patch) | |
| tree | 50ec073f06528c34cca935bea7069c93299f726e /gcc/testsuite/gcc.target | |
| parent | 7b9e837e769474fa5e91958dd2a479837b1176cb (diff) | |
| download | gcc-726682897d877afacb8164130cbbc715f8b44784.zip gcc-726682897d877afacb8164130cbbc715f8b44784.tar.gz gcc-726682897d877afacb8164130cbbc715f8b44784.tar.bz2 | |
fold-const: Ignore padding bits in native_interpret_expr REAL_CST reverse verification [PR108934]
In the following testcase we try to std::bit_cast a (pair of) integral
value(s) which has some non-zero bits in the place of x86 long double
(for 64-bit 16 byte type with 10 bytes actually loaded/stored by hw,
for 32-bit 12 byte) and starting with my PR104522 change we reject that
as native_interpret_expr fails on it. The PR104522 change extends what
has been done before for MODE_COMPOSITE_P (but those don't have any padding
bits) to all floating point types, because e.g. the exact x86 long double
has various bit combinations we don't support, like
pseudo-(denormals,infinities,NaNs) or unnormals. The HW handles some of
those as exceptional cases and others similarly to the non-pseudo ones.
But for the padding bits it actually doesn't load/store those bits at all,
it loads/stores 10 bytes. So, I think we should exempt the padding bits
from the reverse comparison (the native_encode_expr bits for the padding
will be all zeros), which the following patch does. For bit_cast it is
similar to e.g. ignoring padding bits if the destination is a structure
which has padding bits in there.
The change changed auto-init-4.c to how it has been behaving before the
PR105259 change, where some more VCEs can be now done.
2023-03-02 Jakub Jelinek <jakub@redhat.com>
PR c++/108934
* fold-const.cc (native_interpret_expr) <case REAL_CST>: Before memcmp
comparison copy the bytes from ptr to a temporary buffer and clearing
padding bits in there.
* gcc.target/i386/auto-init-4.c: Revert PR105259 change.
* g++.target/i386/pr108934.C: New test.
(cherry picked from commit cc88366a80e35b3e53141f49d3071010ff3c2ef8)
Diffstat (limited to 'gcc/testsuite/gcc.target')
| -rw-r--r-- | gcc/testsuite/gcc.target/i386/auto-init-4.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/gcc/testsuite/gcc.target/i386/auto-init-4.c b/gcc/testsuite/gcc.target/i386/auto-init-4.c index 5b4fd87..d9af8f3 100644 --- a/gcc/testsuite/gcc.target/i386/auto-init-4.c +++ b/gcc/testsuite/gcc.target/i386/auto-init-4.c @@ -15,6 +15,5 @@ long double foo() } -/* The long double init isn't expanded optimally, see PR105259. For ia32 - it uses zero-initialization. */ -/* { dg-final { scan-assembler-times "long\t-16843010" 3 } } */ +/* { dg-final { scan-assembler-times "long\t-16843010" 5 { target { ! ia32 } } } } */ +/* { dg-final { scan-assembler-times "long\t-16843010" 3 { target { ia32 } } } } */ |