Improve on r192635, ExeDepsFix for avx, and add a test case.
rdar:15221834 False AVX register dependencies cause 5x slowdown on
flops-5/6 and significant slowdown on several others.
This was blocking the switch to MI-Sched.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192669 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ExecutionDepsFix.cpp b/lib/CodeGen/ExecutionDepsFix.cpp
index 0d26f9d..031f19c 100644
--- a/lib/CodeGen/ExecutionDepsFix.cpp
+++ b/lib/CodeGen/ExecutionDepsFix.cpp
@@ -557,6 +557,9 @@
for (MachineBasicBlock::reverse_iterator I = MBB->rbegin(), E = MBB->rend();
I != E; ++I) {
+ // Update liveness, including the current instrucion's defs.
+ LiveUnits.stepBackward(*I, *TRI);
+
if (UndefMI == &*I) {
if (!LiveUnits.contains(UndefMI->getOperand(OpIdx).getReg(), *TRI))
TII->breakPartialRegDependency(UndefMI, OpIdx, TRI);
@@ -568,7 +571,6 @@
UndefMI = UndefReads.back().first;
OpIdx = UndefReads.back().second;
}
- LiveUnits.stepBackward(*I, *TRI);
}
}