From 1e87fcf200897b64ca428c8ef80c3ad876828caf Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Sat, 10 Feb 2024 12:51:39 +0100
Subject: [PATCH] libgcc: Fix a bug in _BitInt -> dfp conversions
The ia32 _BitInt support revealed a bug in floatbitint?d.c.
As can be even guessed from how the code is written in the loop,
the intention was to set inexact to non-zero whenever the remainder
after division wasn't zero, but I've ended up just checking whether
the 2 least significant limbs of the remainder were non-zero.
Now, in the dfp/bitint-4.c test in one case the remainder happens
to have least significant 64 bits zero and then the higher limbs are
non-zero; with 32-bit limbs that means 2 least significant limbs are zero
and so the code acted as if it was exactly divisible.
Fixed thusly.
2024-02-10 Jakub Jelinek <jakub@redhat.com>
* soft-fp/floatbitintdd.c (__bid_floatbitintdd): Or in all remainder
limbs into inexact rather than just first two.
* soft-fp/floatbitintsd.c (__bid_floatbitintsd): Likewise.
* soft-fp/floatbitinttd.c (__bid_floatbitinttd): Likewise.
---
libgcc/soft-fp/floatbitintdd.c | 2 +-
libgcc/soft-fp/floatbitintsd.c | 2 +-
libgcc/soft-fp/floatbitinttd.c | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/libgcc/soft-fp/floatbitintdd.c b/libgcc/soft-fp/floatbitintdd.c
index 77c5fd75e0e3..456557294e7e 100644
--- a/libgcc/soft-fp/floatbitintdd.c
+++ b/libgcc/soft-fp/floatbitintdd.c
@@ -114,7 +114,7 @@ __bid_floatbitintdd (const UBILtype *i, SItype iprec)
buf + BITINT_END (q_limbs - 1, 0), q_limbs);
inexact = buf[q_limbs + pow10_limbs];
for (j = 1; j < pow10_limbs; ++j)
- inexact |= buf[q_limbs + pow10_limbs + 1];
+ inexact |= buf[q_limbs + pow10_limbs + j];
}
else
{
diff --git a/libgcc/soft-fp/floatbitintsd.c b/libgcc/soft-fp/floatbitintsd.c
index 5c5ed6cfb7e0..4901aa82af7c 100644
--- a/libgcc/soft-fp/floatbitintsd.c
+++ b/libgcc/soft-fp/floatbitintsd.c
@@ -113,7 +113,7 @@ __bid_floatbitintsd (const UBILtype *i, SItype iprec)
buf + BITINT_END (q_limbs - 1, 0), q_limbs);
inexact = buf[q_limbs + pow10_limbs];
for (j = 1; j < pow10_limbs; ++j)
- inexact |= buf[q_limbs + pow10_limbs + 1];
+ inexact |= buf[q_limbs + pow10_limbs + j];
}
else
{
diff --git a/libgcc/soft-fp/floatbitinttd.c b/libgcc/soft-fp/floatbitinttd.c
index 3bc18e201021..5fff339a8675 100644
--- a/libgcc/soft-fp/floatbitinttd.c
+++ b/libgcc/soft-fp/floatbitinttd.c
@@ -113,7 +113,7 @@ __bid_floatbitinttd (const UBILtype *i, SItype iprec)
buf + BITINT_END (q_limbs - 1, 0), q_limbs);
inexact = buf[q_limbs + pow10_limbs];
for (j = 1; j < pow10_limbs; ++j)
- inexact |= buf[q_limbs + pow10_limbs + 1];
+ inexact |= buf[q_limbs + pow10_limbs + j];
}
else
{
--
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