[llvm] LiveIntervals: Use BumpPtrAllocator (PR #127057)
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 26 08:57:21 PST 2025
https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/127057
>From 0dc0d3f11582542f3eb71d96cdf2f97788e5724c Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Thu, 26 Dec 2024 11:52:38 +0700
Subject: [PATCH 1/3] LiveIntervals: Use BumpPtrAllocator
---
llvm/include/llvm/CodeGen/LiveIntervals.h | 12 ++++++++----
llvm/lib/CodeGen/LiveIntervals.cpp | 9 +++++----
2 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/LiveIntervals.h b/llvm/include/llvm/CodeGen/LiveIntervals.h
index 708917be497ef..65b59a9d8b41c 100644
--- a/llvm/include/llvm/CodeGen/LiveIntervals.h
+++ b/llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -30,6 +30,7 @@
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/MC/LaneBitmask.h"
+#include "llvm/Support/Allocator.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
@@ -64,6 +65,8 @@ class LiveIntervals {
MachineDominatorTree *DomTree = nullptr;
std::unique_ptr<LiveIntervalCalc> LICalc;
+ BumpPtrAllocator Allocator;
+
/// Special pool allocator for VNInfo's (LiveInterval val#).
VNInfo::Allocator VNInfoAllocator;
@@ -170,7 +173,7 @@ class LiveIntervals {
/// Interval removal.
void removeInterval(Register Reg) {
auto &Interval = VirtRegIntervals[Reg];
- delete Interval;
+ Allocator.Deallocate(Interval);
Interval = nullptr;
}
@@ -416,7 +419,8 @@ class LiveIntervals {
if (!LR) {
// Compute missing ranges on demand.
// Use segment set to speed-up initial computation of the live range.
- RegUnitRanges[Unit] = LR = new LiveRange(UseSegmentSetForPhysRegs);
+ RegUnitRanges[Unit] = LR = new (Allocator.Allocate<LiveRange>())
+ LiveRange(UseSegmentSetForPhysRegs);
computeRegUnitRange(*LR, Unit);
}
return *LR;
@@ -433,7 +437,7 @@ class LiveIntervals {
/// Remove computed live range for register unit \p Unit. Subsequent uses
/// should rely on on-demand recomputation.
void removeRegUnit(unsigned Unit) {
- delete RegUnitRanges[Unit];
+ Allocator.Deallocate(RegUnitRanges[Unit]);
RegUnitRanges[Unit] = nullptr;
}
@@ -481,7 +485,7 @@ class LiveIntervals {
bool computeDeadValues(LiveInterval &LI,
SmallVectorImpl<MachineInstr *> *dead);
- static LiveInterval *createInterval(Register Reg);
+ LiveInterval *createInterval(Register Reg);
void printInstrs(raw_ostream &O) const;
void dumpInstrs() const;
diff --git a/llvm/lib/CodeGen/LiveIntervals.cpp b/llvm/lib/CodeGen/LiveIntervals.cpp
index 3485a27335f13..f12bf87023979 100644
--- a/llvm/lib/CodeGen/LiveIntervals.cpp
+++ b/llvm/lib/CodeGen/LiveIntervals.cpp
@@ -144,14 +144,14 @@ bool LiveIntervals::invalidate(
void LiveIntervals::clear() {
// Free the live intervals themselves.
for (unsigned i = 0, e = VirtRegIntervals.size(); i != e; ++i)
- delete VirtRegIntervals[Register::index2VirtReg(i)];
+ Allocator.Deallocate(VirtRegIntervals[Register::index2VirtReg(i)]);
VirtRegIntervals.clear();
RegMaskSlots.clear();
RegMaskBits.clear();
RegMaskBlocks.clear();
for (LiveRange *LR : RegUnitRanges)
- delete LR;
+ Allocator.Deallocate(LR);
RegUnitRanges.clear();
// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
@@ -222,7 +222,7 @@ LLVM_DUMP_METHOD void LiveIntervals::dump() const { print(dbgs()); }
LiveInterval *LiveIntervals::createInterval(Register reg) {
float Weight = reg.isPhysical() ? huge_valf : 0.0F;
- return new LiveInterval(reg, Weight);
+ return new (Allocator.Allocate<LiveInterval>()) LiveInterval(reg, Weight);
}
/// Compute the live interval of a virtual register, based on defs and uses.
@@ -374,7 +374,8 @@ void LiveIntervals::computeLiveInRegUnits() {
LiveRange *LR = RegUnitRanges[Unit];
if (!LR) {
// Use segment set to speed-up initial computation of the live range.
- LR = RegUnitRanges[Unit] = new LiveRange(UseSegmentSetForPhysRegs);
+ LR = RegUnitRanges[Unit] = new (Allocator.Allocate<LiveRange>())
+ LiveRange(UseSegmentSetForPhysRegs);
NewRanges.push_back(Unit);
}
VNInfo *VNI = LR->createDeadDef(Begin, getVNInfoAllocator());
>From 81d263d55831cc4c2363a5b2cd8c5272f01c302b Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Mon, 24 Feb 2025 18:50:33 +0700
Subject: [PATCH 2/3] Use SpecificBumpPtrAllocator for LiveInterval
I didn't realize we used a singly linked list for storing subranges,
but that seems bad.
I didn't realize we used a singly linked list for storing subranges.
That seems bad and we should probably switch this to an array
---
llvm/include/llvm/CodeGen/LiveIntervals.h | 6 +++++-
llvm/lib/CodeGen/LiveIntervals.cpp | 10 +++++-----
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/LiveIntervals.h b/llvm/include/llvm/CodeGen/LiveIntervals.h
index 65b59a9d8b41c..7cee939d352af 100644
--- a/llvm/include/llvm/CodeGen/LiveIntervals.h
+++ b/llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -65,8 +65,12 @@ class LiveIntervals {
MachineDominatorTree *DomTree = nullptr;
std::unique_ptr<LiveIntervalCalc> LICalc;
+ // Allocator for RegUnitRanges and SubRanges.
BumpPtrAllocator Allocator;
+ // Allocator for VirtRegIntervals
+ SpecificBumpPtrAllocator<LiveInterval> LIAllocator;
+
/// Special pool allocator for VNInfo's (LiveInterval val#).
VNInfo::Allocator VNInfoAllocator;
@@ -173,7 +177,7 @@ class LiveIntervals {
/// Interval removal.
void removeInterval(Register Reg) {
auto &Interval = VirtRegIntervals[Reg];
- Allocator.Deallocate(Interval);
+ // FIXME: SpecificBumpPtrAllocator missing deallocate for asan poisoning
Interval = nullptr;
}
diff --git a/llvm/lib/CodeGen/LiveIntervals.cpp b/llvm/lib/CodeGen/LiveIntervals.cpp
index f12bf87023979..fd5cc38358319 100644
--- a/llvm/lib/CodeGen/LiveIntervals.cpp
+++ b/llvm/lib/CodeGen/LiveIntervals.cpp
@@ -142,10 +142,6 @@ bool LiveIntervals::invalidate(
}
void LiveIntervals::clear() {
- // Free the live intervals themselves.
- for (unsigned i = 0, e = VirtRegIntervals.size(); i != e; ++i)
- Allocator.Deallocate(VirtRegIntervals[Register::index2VirtReg(i)]);
- VirtRegIntervals.clear();
RegMaskSlots.clear();
RegMaskBits.clear();
RegMaskBlocks.clear();
@@ -154,6 +150,10 @@ void LiveIntervals::clear() {
Allocator.Deallocate(LR);
RegUnitRanges.clear();
+ // Free the live intervals themselves.
+ LIAllocator.DestroyAll();
+ VirtRegIntervals.clear();
+
// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
VNInfoAllocator.Reset();
}
@@ -222,7 +222,7 @@ LLVM_DUMP_METHOD void LiveIntervals::dump() const { print(dbgs()); }
LiveInterval *LiveIntervals::createInterval(Register reg) {
float Weight = reg.isPhysical() ? huge_valf : 0.0F;
- return new (Allocator.Allocate<LiveInterval>()) LiveInterval(reg, Weight);
+ return new (LIAllocator.Allocate()) LiveInterval(reg, Weight);
}
/// Compute the live interval of a virtual register, based on defs and uses.
>From 4fb8fd4cbc5975baaa3139b6db6c1c5d0cc5b585 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Wed, 26 Feb 2025 23:53:44 +0700
Subject: [PATCH 3/3] Use yet another allocator for LiveRanges
Not sure it's worth it for these, there should never be all that
many. We could pre-allocate the maximum size up front.
---
llvm/include/llvm/CodeGen/LiveIntervals.h | 9 ++++++---
llvm/lib/CodeGen/LiveIntervals.cpp | 3 +--
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/LiveIntervals.h b/llvm/include/llvm/CodeGen/LiveIntervals.h
index 7cee939d352af..4a4d53ee7c25e 100644
--- a/llvm/include/llvm/CodeGen/LiveIntervals.h
+++ b/llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -65,12 +65,15 @@ class LiveIntervals {
MachineDominatorTree *DomTree = nullptr;
std::unique_ptr<LiveIntervalCalc> LICalc;
- // Allocator for RegUnitRanges and SubRanges.
+ // Allocator for SubRanges.
BumpPtrAllocator Allocator;
// Allocator for VirtRegIntervals
SpecificBumpPtrAllocator<LiveInterval> LIAllocator;
+ // Allocator for RegUnitRanges
+ SpecificBumpPtrAllocator<LiveRange> LRAllocator;
+
/// Special pool allocator for VNInfo's (LiveInterval val#).
VNInfo::Allocator VNInfoAllocator;
@@ -423,8 +426,8 @@ class LiveIntervals {
if (!LR) {
// Compute missing ranges on demand.
// Use segment set to speed-up initial computation of the live range.
- RegUnitRanges[Unit] = LR = new (Allocator.Allocate<LiveRange>())
- LiveRange(UseSegmentSetForPhysRegs);
+ RegUnitRanges[Unit] = LR =
+ new (LRAllocator.Allocate()) LiveRange(UseSegmentSetForPhysRegs);
computeRegUnitRange(*LR, Unit);
}
return *LR;
diff --git a/llvm/lib/CodeGen/LiveIntervals.cpp b/llvm/lib/CodeGen/LiveIntervals.cpp
index fd5cc38358319..2b46e4e6393d5 100644
--- a/llvm/lib/CodeGen/LiveIntervals.cpp
+++ b/llvm/lib/CodeGen/LiveIntervals.cpp
@@ -146,8 +146,7 @@ void LiveIntervals::clear() {
RegMaskBits.clear();
RegMaskBlocks.clear();
- for (LiveRange *LR : RegUnitRanges)
- Allocator.Deallocate(LR);
+ LRAllocator.DestroyAll();
RegUnitRanges.clear();
// Free the live intervals themselves.
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