diff options
| -rw-r--r-- | lib/CodeGen/MachineInstr.cpp | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp index bfb722bf3b..7ff79b3a22 100644 --- a/lib/CodeGen/MachineInstr.cpp +++ b/lib/CodeGen/MachineInstr.cpp @@ -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; } |