https://github.com/boxu-zhang updated
https://github.com/llvm/llvm-project/pull/76029
>From 60030d96d27d23ef2049a3888d65721be51c4481 Mon Sep 17 00:00:00 2001
From: "boxu.zhang" <boxu.zh...@hotmail.com>
Date: Wed, 20 Dec 2023 17:35:25 +0800
Subject: [PATCH] Make 'UnrollMaxUpperBound' to be overridable by target. The
default value is still 8 and the command line argument
'--unroll-max-upperbound' takes final effect if provided.
---
llvm/include/llvm/Analysis/TargetTransformInfo.h | 4 ++++
llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp | 9 ++++++---
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfo.h
b/llvm/include/llvm/Analysis/TargetTransformInfo.h
index f5114fa40c70ad..6fc697c37c3c33 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -560,6 +560,10 @@ class TargetTransformInfo {
// (set to UINT_MAX to disable). This does not apply in cases where the
// loop is being fully unrolled.
unsigned MaxCount;
+ /// Set the maximum upper bound of trip count. Allowing the MaxUpperBound
+ /// to be overrided by a target gives more flexiblity on certain cases.
+ /// By default, MaxUpperBound uses UnrollMaxUpperBound which value is 8.
+ unsigned MaxUpperBound;
/// Set the maximum unrolling factor for full unrolling. Like MaxCount, but
/// applies even if full unrolling is selected. This allows a target to
fall
/// back to Partial unrolling if full unrolling is above
FullUnrollMaxCount.
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index f14541a1a037e6..ddc532ea24e275 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -200,6 +200,7 @@ TargetTransformInfo::UnrollingPreferences
llvm::gatherUnrollingPreferences(
UP.Count = 0;
UP.DefaultUnrollRuntimeCount = 8;
UP.MaxCount = std::numeric_limits<unsigned>::max();
+ UP.MaxUpperBound = UnrollMaxUpperBound;
UP.FullUnrollMaxCount = std::numeric_limits<unsigned>::max();
UP.BEInsns = 2;
UP.Partial = false;
@@ -237,6 +238,8 @@ TargetTransformInfo::UnrollingPreferences
llvm::gatherUnrollingPreferences(
UP.MaxPercentThresholdBoost = UnrollMaxPercentThresholdBoost;
if (UnrollMaxCount.getNumOccurrences() > 0)
UP.MaxCount = UnrollMaxCount;
+ if (UnrollMaxUpperBound.getNumOccurrences() > 0)
+ UP.MaxUpperBound = UnrollMaxUpperBound;
if (UnrollFullMaxCount.getNumOccurrences() > 0)
UP.FullUnrollMaxCount = UnrollFullMaxCount;
if (UnrollAllowPartial.getNumOccurrences() > 0)
@@ -777,7 +780,7 @@ shouldPragmaUnroll(Loop *L, const PragmaInfo &PInfo,
return TripCount;
if (PInfo.PragmaEnableUnroll && !TripCount && MaxTripCount &&
- MaxTripCount <= UnrollMaxUpperBound)
+ MaxTripCount <= UP.MaxUpperBound)
return MaxTripCount;
// if didn't return until here, should continue to other priorties
@@ -952,7 +955,7 @@ bool llvm::computeUnrollCount(
// cost of exact full unrolling. As such, if we have an exact count and
// found it unprofitable, we'll never chose to bounded unroll.
if (!TripCount && MaxTripCount && (UP.UpperBound || MaxOrZero) &&
- MaxTripCount <= UnrollMaxUpperBound) {
+ MaxTripCount <= UP.MaxUpperBound) {
UP.Count = MaxTripCount;
if (auto UnrollFactor = shouldFullUnroll(L, TTI, DT, SE, EphValues,
MaxTripCount, UCE, UP)) {
@@ -1026,7 +1029,7 @@ bool llvm::computeUnrollCount(
}
// Don't unroll a small upper bound loop unless user or TTI asked to do so.
- if (MaxTripCount && !UP.Force && MaxTripCount < UnrollMaxUpperBound) {
+ if (MaxTripCount && !UP.Force && MaxTripCount < UP.MaxUpperBound) {
UP.Count = 0;
return false;
}
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