Skip to content
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

[LoopUnroll] Do not pipeline epilog loops generated by loop unrolling #5027

Merged
merged 3 commits into from
Nov 5, 2024
Merged

[LoopUnroll] Do not pipeline epilog loops generated by loop unrolling #5027

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
8f28da9
[BACKEND] Do not pipeline epilog loops generated by loop unrolling
htyu Oct 31, 2024
3eb537b
Fix for constant-bound loop where no epilog will be generated.
htyu Oct 31, 2024
6e16e01
Simplified based on MLIR-side changes.
htyu Nov 5, 2024
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
20 changes: 14 additions & 6 deletions lib/Dialect/Triton/Transforms/LoopUnroll.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,21 +22,22 @@

namespace mlir::triton {

static const char *loopUnrollFactorAttrName = "tt.loop_unroll_factor";

namespace {

class LoopUnrollPass : public TritonLoopUnrollBase<LoopUnrollPass> {

int getUnrollFactorOrDefault(scf::ForOp forOp) {
// Use the attribute attached to the loop if it exists otherwise set the
// factor to 1 to suppress the unrolling.
if (auto factor = forOp->getAttrOfType<IntegerAttr>(
mlir::triton::loopUnrollFactorAttrName))
if (auto factor =
forOp->getAttrOfType<IntegerAttr>(loopUnrollFactorAttrName))
return factor.getInt();
return 1;
}

const char *loopUnrollFactorAttrName = "tt.loop_unroll_factor";
const char *pipelineStagesAttrName = "tt.num_stages";

public:
LoopUnrollPass() = default;
LoopUnrollPass(const LoopUnrollPass &) {}
Expand All @@ -49,11 +50,18 @@ class LoopUnrollPass : public TritonLoopUnrollBase<LoopUnrollPass> {
loops.push_back(forOp);
});

auto ctx = getOperation()->getContext();
for (auto loop : loops) {
auto unrollFactor = getUnrollFactorOrDefault(loop);
loop->removeAttr(mlir::triton::loopUnrollFactorAttrName);
loop->removeAttr(loopUnrollFactorAttrName);
LDBG("Unrolling loop by " << unrollFactor << " times\n" << loop);
(void)loopUnrollByFactor(loop, unrollFactor);
auto resultLoops = loopUnrollByFactor(loop, unrollFactor);
// Do not pipeline the epilog loop.
if (succeeded(resultLoops) && resultLoops->epilogueLoopOp) {
(*resultLoops->epilogueLoopOp)
->setAttr(pipelineStagesAttrName,
mlir::IntegerAttr::get(IntegerType::get(ctx, 32), 1));
}
}
}
};
Expand Down
1 change: 1 addition & 0 deletions test/Triton/loop-unroll.mlir
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ tt.func @add_kernel_unroll(%arg0: tensor<256x!tt.ptr<f32>>, %arg1: i32) {
// CHECK: scf.for
// CHECK: tt.load
// CHECK-NOT: tt.load
// CHECK: tt.num_stages = 1 : i32
%2:2 = scf.for %arg3 = %c1_i32 to %arg1 step %c1_i32 iter_args(%arg4 = %1, %arg5 = %arg0) -> (tensor<256xf32>, tensor<256x!tt.ptr<f32>>) : i32 {
%3 = tt.load %arg5 : tensor<256x!tt.ptr<f32>>
%4 = arith.addf %arg4, %3 : tensor<256xf32>
Expand Down
Loading