maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[MachineCSE] Rewrite a loop checking if a block is in a set of blocks without using a set. NFC. 

Summary:
Using a set is unnecessary here an in some cases (see e.g. PR37277)
takes significant amount of time to just insert values into it. In this
particular case all we need is just to check if we find the block we are
looking for or not.

Reviewers: davide

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D46411

llvm-svn: 331502
This commit is contained in:
Michael Zolotukhin 2018-05-04 01:40:05 +00:00
parent 0fd685353d
commit 131e74910c
1 changed files with 5 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
llvm/lib/CodeGen/MachineCSE.cpp
View File

@ -445,15 +445,13 @@ bool MachineCSE::isProfitableToCSE(unsigned CSReg, unsigned Reg,
// Heuristics #3: If the common subexpression is used by PHIs, do not reuse
// it unless the defined value is already used in the BB of the new use.
bool HasPHI = false;
SmallPtrSet<MachineBasicBlock*, 4> CSBBs;
for (MachineInstr &MI : MRI->use_nodbg_instructions(CSReg)) {
HasPHI |= MI.isPHI();
CSBBs.insert(MI.getParent());
for (MachineInstr &UseMI : MRI->use_nodbg_instructions(CSReg)) {
HasPHI |= UseMI.isPHI();
if (UseMI.getParent() == MI->getParent())
return true;
}
if (!HasPHI)
return true;
return CSBBs.count(MI->getParent());
return !HasPHI;
}
void MachineCSE::EnterScope(MachineBasicBlock *MBB) {