From: Joseph Myers <jos...@codesourcery.com>
The math-emu macros _FP_TO_INT and _FP_TO_INT_ROUND are supposed to
saturate their results for out-of-range arguments, except in the case
rsigned == 2 (when instead the low bits of the result are taken).
However, in the case rsigned == 0 (converting to unsigned integers),
they mistakenly produce 0 for positive results and the maximum
unsigned integer for negative results, the opposite of correct
unsigned saturation. This patch fixes the logic.
Signed-off-by: Joseph Myers <jos...@codesourcery.com>
---
I intend to make the corresponding changes to the glibc/libgcc copy of
this code, given that it would be desirable to resync the Linux and
glibc/libgcc copies (the latter has had many enhancements and bug
fixes since it was copied into Linux), although strictly this
incorrect saturation is only a bug when trying to emulate particular
instruction semantics, not when used in userspace to implement C
operations where the results of out-of-range conversions are
unspecified or undefined.
diff --git a/include/math-emu/op-common.h b/include/math-emu/op-common.h
index 9696a5e..70fe5e9 100644
--- a/include/math-emu/op-common.h
+++ b/include/math-emu/op-common.h
@@ -685,7 +685,7 @@ do {
\
else
\
{
\
r = 0;
\
- if (X##_s)
\
+ if (!X##_s)
\
r = ~r;
\
}
\
FP_SET_EXCEPTION(FP_EX_INVALID);
\
@@ -762,7 +762,7 @@ do {
\
if (!rsigned)
\
{
\
r = 0;
\
- if (X##_s)
\
+ if (!X##_s)
\
r = ~r;
\
}
\
else if (rsigned != 2)
\
--
Joseph S. Myers
jos...@codesourcery.com
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