diff mbox

fpu/softfloat: Don't set Invalid for float-to-int(MAXINT)

Message ID 20180510140141.12120-1-peter.maydell@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Peter Maydell May 10, 2018, 2:01 p.m. UTC 
In float-to-integer conversion, if the floating point input
converts exactly to the largest or smallest integer that
fits in to the result type, this is not an overflow.
In this situation we were producing the correct result value,
but were incorrectly setting the Invalid flag.
For example for Arm A64, "FCVTAS w0, d0" on an input of
0x41dfffffffc00000 should produce 0x7fffffff and set no flags.

Fix the boundary case to take the right half of the if()
statements.

This fixes a regression from 2.11 introduced by the softfloat
refactoring.

Cc: qemu-stable@nongnu.org
Fixes: ab52f973a50
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 fpu/softfloat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Richard Henderson May 10, 2018, 3:20 p.m. UTC | #1 
On 05/10/2018 07:01 AM, Peter Maydell wrote:
> In float-to-integer conversion, if the floating point input
> converts exactly to the largest or smallest integer that
> fits in to the result type, this is not an overflow.
> In this situation we were producing the correct result value,
> but were incorrectly setting the Invalid flag.
> For example for Arm A64, "FCVTAS w0, d0" on an input of
> 0x41dfffffffc00000 should produce 0x7fffffff and set no flags.
> 
> Fix the boundary case to take the right half of the if()
> statements.
> 
> This fixes a regression from 2.11 introduced by the softfloat
> refactoring.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: ab52f973a50
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  fpu/softfloat.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~
diff mbox

Patch

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 8401b37bd4..9bcaaebe4f 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -1368,14 +1368,14 @@  static int64_t round_to_int_and_pack(FloatParts in, int rmode,
             r = UINT64_MAX;
         }
         if (p.sign) {
-            if (r < -(uint64_t) min) {
+            if (r <= -(uint64_t) min) {
                 return -r;
             } else {
                 s->float_exception_flags = orig_flags | float_flag_invalid;
                 return min;
             }
         } else {
-            if (r < max) {
+            if (r <= max) {
                 return r;
             } else {
                 s->float_exception_flags = orig_flags | float_flag_invalid;