tree 87297f7ccc5bbc3116bdb4594c24d908afbef960
parent 0f75548f9fdbdedf36c1ea732d715a419186b7a1
author Ranjeet Singh <Ranjeet.Singh@arm.com> 1493214103 +0000
committer Ranjeet Singh <Ranjeet.Singh@arm.com> 1493214103 +0000

Fix signed multiplication with overflow fallback.

For targets that don't have ISD::MULHS or ISD::SMUL_LOHI for the type
and the double width type is illegal, then the two operands are
sign extended to twice their size then multiplied to check for overflow.
The extended upper halves were mismatched causing an incorrect result.
This fixes the mismatch.

A test was added for ARM V6-M where the bug was detected.

Patch by James Duley.

Differential Revision: https://reviews.llvm.org/D31807


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301404 91177308-0d34-0410-b5e6-96231b3b80d8