Skip to content

[RegAlloc] Add a flag to toggle non-trivial rematerialization #165630

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

[RegAlloc] Add a flag to toggle non-trivial rematerialization #165630

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
4676fef
[RegAlloc] Add a flag to toggle non-trivial rematerialization
ZequanWu Oct 29, 2025
50cf8b4
format
ZequanWu Oct 29, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 12 additions & 0 deletions llvm/lib/CodeGen/TargetInstrInfo.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,10 @@ static cl::opt<unsigned int> MaxAccumulatorWidth(
"acc-max-width", cl::Hidden, cl::init(3),
cl::desc("Maximum number of branches in the accumulator tree"));

static cl::opt<bool>
AllowNTRemat("allow-none-trival-remat", cl::init(true), cl::Hidden,
cl::desc("Allow non-trivial rematerialization by default"));

TargetInstrInfo::~TargetInstrInfo() = default;

const TargetRegisterClass *
Expand Down Expand Up @@ -1657,6 +1661,14 @@ bool TargetInstrInfo::isReMaterializableImpl(
// same virtual register, though.
if (MO.isDef() && Reg != DefReg)
return false;

// Don't allow any virtual-register uses. Rematting an instruction with
// virtual register uses would length the live ranges of the uses, which
// is not necessarily a good idea, certainly not "trivial".
if (!AllowNTRemat) {
if (MO.isUse())
return false;
}
}

// Everything checked out.
Expand Down