tree b594ef9dc17a3ba9dcfad4089b1dd36c82794d1a
parent 6e5b564f917786b9967b2a0e5a8cb2c898dac03e
author Craig Topper <craig.topper@intel.com> 1555774004 +0000
committer Craig Topper <craig.topper@intel.com> 1555774004 +0000

[X86] Disable argument copy elision for arguments passed via pointers

Summary:
If you pass two 1024 bit vectors in IR with AVX2 on Windows 64. Both vectors will be split in four 256 bit pieces. The four pieces of the first argument will be passed indirectly using 4 gprs. The second argument will get passed via pointers in memory.

The PartOffsets stored for the second argument are all in terms of its original 1024 bit size. So the PartOffsets for each piece are 32 bytes apart. So if we consider it for copy elision we'll only load an 8 byte pointer, but we'll move the address 32 bytes. The stack object size we create for the first part is probably wrong too.

This issue was encountered by ISPC. I'm working on getting a reduce test case, but wanted to go ahead and get feedback on the fix.

Reviewers: rnk

Reviewed By: rnk

Subscribers: dbabokin, llvm-commits, hiraditya

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60801

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358817 91177308-0d34-0410-b5e6-96231b3b80d8