Commit Graph

3 Commits

Author SHA1 Message Date
Hans Wennborg 9b9a5358dd Re-commit r301040 "X86: Don't emit zero-byte functions on Windows"
In addition to the original commit, tighten the condition for when to
pad empty functions to COFF Windows.  This avoids running into problems
when targeting e.g. Win32 AMDGPU, which caused test failures when this
was committed initially.

llvm-svn: 301047
2017-04-21 21:48:41 +00:00
Hans Wennborg 04593000d8 Revert r301040 "X86: Don't emit zero-byte functions on Windows"
This broke almost all bots. Reverting while fixing.

llvm-svn: 301041
2017-04-21 21:10:37 +00:00
Hans Wennborg cb3e810714 X86: Don't emit zero-byte functions on Windows
Empty functions can lead to duplicate entries in the Guard CF Function
Table of a binary due to multiple functions sharing the same RVA,
causing the kernel to refuse to load that binary.

We had a terrific bug due to this in Chromium.

It turns out we were already doing this for Mach-O in certain
situations. This patch expands the code for that in
AsmPrinter::EmitFunctionBody() and renames
TargetInstrInfo::getNoopForMachoTarget() to simply getNoop() since it
seems it was used for not just Mach-O anyway.

Differential Revision: https://reviews.llvm.org/D32330

llvm-svn: 301040
2017-04-21 20:58:12 +00:00