- Adds support for inserting vzerouppers before tail-calls.
This is enabled implicitly by having MachineInstr::copyImplicitOps preserve
regmask operands, which allows VZeroUpperInserter to see where tail-calls use
vector registers.
- Fixes a bug that caused the previous version of this optimization to miss some
vzeroupper insertion points in loops. (Loops-with-vector-code that followed
loops-without-vector-code were mistakenly overlooked by the previous version).
- New algorithm never revisits instructions.
Fixes <rdar://problem/16228798>
llvm-svn: 204021
- The fix to PR17631 fixes part of the cases where 'vzeroupper' should
not be issued before 'call' insn. There're other cases where helper
calls will be inserted not limited to epilog. These helper calls do
not follow the standard calling convention and won't clobber any YMM
registers. (So far, all call conventions will clobber any or part of
YMM registers.)
This patch enhances the previous fix to cover more cases 'vzerosupper' should
not be inserted by checking if that function call won't clobber any YMM
registers and skipping it if so.
llvm-svn: 196261
- Skip instructions added in prolog. For specific targets, prolog may
insert helper function calls (e.g. _chkstk will be called when
there're more than 4K bytes allocated on stack). However, these
helpers don't use/def YMM/XMM registers.
llvm-svn: 193261
The previous MRI.isPhysRegUsed(YMM0) would also return true when the
function contains a call to a function that may clobber YMM0. That's
most of them.
Checking the use-def chains allows us to skip functions that don't
explicitly mention YMM registers.
llvm-svn: 166110
generator to it. For non-bundle instructions, these behave exactly the same
as the MC layer API.
For properties like mayLoad / mayStore, look into the bundle and if any of the
bundled instructions has the property it would return true.
For properties like isPredicable, only return true if *all* of the bundled
instructions have the property.
For properties like canFoldAsLoad, isCompare, conservatively return false for
bundles.
llvm-svn: 146026
SSE transition penalty. The pass is enabled through the "x86-use-vzeroupper"
llc command line option. This is only the first step (very naive and
conservative one) to sketch out the idea, but proper DFA is coming next
to allow smarter decisions. Comments and ideas now and in further commits
will be very appreciated.
llvm-svn: 138317
Chandler Carruth