Skip to content

[InstCombine] FP type minimization looks through fneg. #715

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 1 commit into
base: aie-public
Choose a base branch
from
Open

[InstCombine] FP type minimization looks through fneg. #715

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
8 changes: 8 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// Modifications (c) Copyright 2025 Advanced Micro Devices, Inc. or its
// affiliates
//
//===----------------------------------------------------------------------===//
//
// This file implements the visit functions for cast operations.
Expand Down Expand Up @@ -1674,6 +1677,11 @@ static Type *shrinkFPConstantVector(Value *V, bool PreferBFloat) {

/// Find the minimum FP type we can safely truncate to.
static Type *getMinimumFPType(Value *V, bool PreferBFloat) {
// Look through fneg - negation doesn't change the type requirements
Value *X;
if (match(V, m_FNeg(m_Value(X))))
Copy link
Collaborator

@andcarminati andcarminati Nov 20, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Could we have a test?

Copy link
Collaborator Author

@martien-de-jong martien-de-jong Nov 20, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Cline complied.

Copy link
Collaborator Author

@martien-de-jong martien-de-jong Nov 20, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

But Konstantin would be happier with a codegen combine.

V = X;

if (auto *FPExt = dyn_cast<FPExtInst>(V))
return FPExt->getOperand(0)->getType();

Expand Down