RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2024-12-05 02:07:16 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Don't move normal loads across volatile/atomic loads.

Browse Source 
It is technically allowed to move a normal load across a volatile load,
but probably not a good idea.

It is not allowed to move a load across an atomic load with
Ordering > Monotonic, and we model those with MOVolatile as well.

I recently removed the mayStore flag from atomic load instructions, so
they don't need a pseudo-opcode. This patch makes up for the difference.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162857 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2012-08-29 20:48:45 +00:00
parent 688c1cd6c9
commit 0d75858395
1 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
lib/CodeGen/MachineInstr.cpp
View File

@ -1343,7 +1343,12 @@ bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII,
AliasAnalysis *AA,
bool &SawStore) const {
// Ignore stuff that we obviously can't move.
if (mayStore() || isCall()) {
//
// Treat volatile loads as stores. This is not strictly necessary for
// volatiles, but it is required for atomic loads. It is now allowed to move
// a load across an atomic load with Ordering > Monotonic.
if (mayStore() || isCall() ||
(mayLoad() && hasVolatileMemoryRef())) {
SawStore = true;
return false;
}
@ -1359,8 +1364,8 @@ bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII,
// load.
if (mayLoad() && !isInvariantLoad(AA))
// Otherwise, this is a real load. If there is a store between the load and
// end of block, or if the load is volatile, we can't move it.
return !SawStore && !hasVolatileMemoryRef();
// end of block, we can't move it.
return !SawStore;
return true;
}