https://bugs.kde.org/show_bug.cgi?id=406256
Bug ID: 406256
Summary: PPC64, vector floating point instructions don't handle
subnormal according to VSCR[NJ] bit setting
Product: valgrind
Version: 3.15 SVN
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: vex
Assignee: jsew...@acm.org
Reporter: c...@us.ibm.com
Target Milestone: ---
The handling of subnormal arguments and results for the various vector floating
point instructions is controlled by the VSCR[NJ] bit.
VSCR[NJ] = 0 Denormalized values are handled as
specified by Java and the IEEE standard.
VSCR[NJ] = 1 If an element in a source VR contains a denormalized
value, the value 0 is used instead. If an instruction
causes an Underflow Exception, the corresponding element
in the target VR is set to 0. In both cases the 0 has
the same sign as the denormalized or underflowing value.
Convert negative zero to positive zero.
On BE systems, the VSCR[NJ] bit is set to 1. On LE systems, the setting is 0
as required by the ABI. Valgrind is generating results based on the setting of
the bit in the host. If the user changes the bit in their application, the
subnormal results do not match the expected results. This is due to the fact
Valgrind does not track the setting of the bit.
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