[CSSPGO] Undoing the concept of dangling pseudo probe

As a follow-up to https://reviews.llvm.org/D104129, I'm cleaning up the danling probe related code in both the compiler and llvm-profgen.

I'm seeing a 5% size win for the pseudo_probe section for SPEC2017 and 10% for Ciner. Certain benchmark such as 602.gcc has a 20% size win. No obvious difference seen on build time for SPEC2017 and Cinder.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D104477

1 files changed, 0 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 1011f52..c6914dc 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -901,32 +901,6 @@ MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB) {
   normalizeSuccProbs();
 }
 
-/// A block emptied (i.e., with all instructions moved out of it) won't be
-/// sampled at run time. In such cases, AutoFDO will be informed of zero samples
-/// collected for the block. This is not accurate and could lead to misleading
-/// weights assigned for the block. A way to mitigate that is to treat such
-/// block as having unknown counts in the AutoFDO profile loader and allow the
-/// counts inference tool a chance to calculate a relatively reasonable weight
-/// for it. This can be done by moving all pseudo probes in the emptied block
-/// i.e, /c this, to before /c ToMBB and tag them dangling. Note that this is
-/// not needed for dead blocks which really have a zero weight. It's per
-/// transforms to decide whether to call this function or not.
-void MachineBasicBlock::moveAndDanglePseudoProbes(MachineBasicBlock *ToMBB) {
-  SmallVector<MachineInstr *, 4> ToBeMoved;
-  for (MachineInstr &MI : instrs()) {
-    if (MI.isPseudoProbe()) {
-      MI.addPseudoProbeAttribute(PseudoProbeAttributes::Dangling);
-      ToBeMoved.push_back(&MI);
-    }
-  }
-
-  MachineBasicBlock::iterator I = ToMBB->getFirstTerminator();
-  for (MachineInstr *MI : ToBeMoved) {
-    MI->removeFromParent();
-    ToMBB->insert(I, MI);
-  }
-}
-
 bool MachineBasicBlock::isPredecessor(const MachineBasicBlock *MBB) const {
   return is_contained(predecessors(), MBB);
 }