[gcc r14-8912] libgcc: Fix a bug in _BitInt -> dfp conversions

[gcc r14-8912] libgcc: Fix a bug in _BitInt -> dfp conversions

[Jakub Jelinek]

https://gcc.gnu.org/g:1e87fcf200897b64ca428c8ef80c3ad876828caf

commit r14-8912-g1e87fcf200897b64ca428c8ef80c3ad876828caf
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Feb 10 12:51:39 2024 +0100

    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.

Diff:
---
 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
 	{