[llvm] r221203 - Use AA in LoadCombine
Hal Finkel
hfinkel at anl.gov
Mon Nov 3 15:19:17 PST 2014
Author: hfinkel
Date: Mon Nov 3 17:19:16 2014
New Revision: 221203
URL: http://llvm.org/viewvc/llvm-project?rev=221203&view=rev
Log:
Use AA in LoadCombine
LoadCombine can be smarter about aborting when a writing instruction is
encountered, instead of aborting upon encountering any writing instruction, use
an AliasSetTracker, and only abort when encountering some write that might
alias with the loads that could potentially be combined.
This was originally motivated by comments made (and a test case provided) by
David Majnemer in response to PR21448. It turned out that LoadCombine was not
responsible for that PR, but LoadCombine should also be improved so that
unrelated stores (and @llvm.assume) don't interrupt load combining.
Added:
llvm/trunk/test/Transforms/LoadCombine/load-combine-aa.ll
llvm/trunk/test/Transforms/LoadCombine/load-combine-assume.ll
Modified:
llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
llvm/trunk/lib/Analysis/AliasSetTracker.cpp
llvm/trunk/lib/Transforms/Scalar/LoadCombine.cpp
Modified: llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/AliasSetTracker.h?rev=221203&r1=221202&r2=221203&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/AliasSetTracker.h (original)
+++ llvm/trunk/include/llvm/Analysis/AliasSetTracker.h Mon Nov 3 17:19:16 2014
@@ -370,6 +370,10 @@ public:
/// alias sets.
bool containsPointer(Value *P, uint64_t Size, const AAMDNodes &AAInfo) const;
+ /// Return true if the specified instruction "may" (or must) alias one of the
+ /// members in any of the sets.
+ bool containsUnknown(Instruction *I) const;
+
/// getAliasAnalysis - Return the underlying alias analysis object used by
/// this tracker.
AliasAnalysis &getAliasAnalysis() const { return AA; }
Modified: llvm/trunk/lib/Analysis/AliasSetTracker.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasSetTracker.cpp?rev=221203&r1=221202&r2=221203&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasSetTracker.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasSetTracker.cpp Mon Nov 3 17:19:16 2014
@@ -242,7 +242,12 @@ bool AliasSetTracker::containsPointer(Va
return false;
}
-
+bool AliasSetTracker::containsUnknown(Instruction *Inst) const {
+ for (const_iterator I = begin(), E = end(); I != E; ++I)
+ if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
+ return true;
+ return false;
+}
AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
AliasSet *FoundSet = nullptr;
Modified: llvm/trunk/lib/Transforms/Scalar/LoadCombine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoadCombine.cpp?rev=221203&r1=221202&r2=221203&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoadCombine.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoadCombine.cpp Mon Nov 3 17:19:16 2014
@@ -15,6 +15,8 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/TargetFolder.h"
#include "llvm/Pass.h"
#include "llvm/IR/DataLayout.h"
@@ -51,11 +53,12 @@ struct LoadPOPPair {
class LoadCombine : public BasicBlockPass {
LLVMContext *C;
const DataLayout *DL;
+ AliasAnalysis *AA;
public:
LoadCombine()
: BasicBlockPass(ID),
- C(nullptr), DL(nullptr) {
+ C(nullptr), DL(nullptr), AA(nullptr) {
initializeSROAPass(*PassRegistry::getPassRegistry());
}
@@ -225,19 +228,23 @@ bool LoadCombine::runOnBasicBlock(BasicB
if (skipOptnoneFunction(BB) || !DL)
return false;
+ AA = &getAnalysis<AliasAnalysis>();
+
IRBuilder<true, TargetFolder>
TheBuilder(BB.getContext(), TargetFolder(DL));
Builder = &TheBuilder;
DenseMap<const Value *, SmallVector<LoadPOPPair, 8>> LoadMap;
+ AliasSetTracker AST(*AA);
bool Combined = false;
unsigned Index = 0;
for (auto &I : BB) {
- if (I.mayWriteToMemory() || I.mayThrow()) {
+ if (I.mayThrow() || (I.mayWriteToMemory() && AST.containsUnknown(&I))) {
if (combineLoads(LoadMap))
Combined = true;
LoadMap.clear();
+ AST.clear();
continue;
}
LoadInst *LI = dyn_cast<LoadInst>(&I);
@@ -250,6 +257,7 @@ bool LoadCombine::runOnBasicBlock(BasicB
if (!POP.Pointer)
continue;
LoadMap[POP.Pointer].push_back(LoadPOPPair(LI, POP, Index++));
+ AST.add(LI);
}
if (combineLoads(LoadMap))
Combined = true;
@@ -258,6 +266,9 @@ bool LoadCombine::runOnBasicBlock(BasicB
void LoadCombine::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
+
+ AU.addRequired<AliasAnalysis>();
+ AU.addPreserved<AliasAnalysis>();
}
char LoadCombine::ID = 0;
@@ -266,5 +277,9 @@ BasicBlockPass *llvm::createLoadCombineP
return new LoadCombine();
}
-INITIALIZE_PASS(LoadCombine, "load-combine", "Combine Adjacent Loads", false,
- false)
+INITIALIZE_PASS_BEGIN(LoadCombine, "load-combine", "Combine Adjacent Loads",
+ false, false)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_END(LoadCombine, "load-combine", "Combine Adjacent Loads",
+ false, false)
+
Added: llvm/trunk/test/Transforms/LoadCombine/load-combine-aa.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoadCombine/load-combine-aa.ll?rev=221203&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoadCombine/load-combine-aa.ll (added)
+++ llvm/trunk/test/Transforms/LoadCombine/load-combine-aa.ll Mon Nov 3 17:19:16 2014
@@ -0,0 +1,39 @@
+; RUN: opt -basicaa -load-combine -instcombine -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i64 @test1(i32* nocapture readonly noalias %a, i32* nocapture readonly noalias %b) {
+; CHECK-LABEL: @test1
+
+; CHECK: load i64*
+; CHECK: ret i64
+
+ %load1 = load i32* %a, align 4
+ %conv = zext i32 %load1 to i64
+ %arrayidx1 = getelementptr inbounds i32* %a, i64 1
+ store i32 %load1, i32* %b, align 4
+ %load2 = load i32* %arrayidx1, align 4
+ %conv2 = zext i32 %load2 to i64
+ %shl = shl nuw i64 %conv2, 32
+ %add = or i64 %shl, %conv
+ ret i64 %add
+}
+
+define i64 @test2(i32* nocapture readonly %a, i32* nocapture readonly %b) {
+; CHECK-LABEL: @test2
+
+; CHECK: load i32*
+; CHECK: load i32*
+; CHECK: ret i64
+
+ %load1 = load i32* %a, align 4
+ %conv = zext i32 %load1 to i64
+ %arrayidx1 = getelementptr inbounds i32* %a, i64 1
+ store i32 %load1, i32* %b, align 4
+ %load2 = load i32* %arrayidx1, align 4
+ %conv2 = zext i32 %load2 to i64
+ %shl = shl nuw i64 %conv2, 32
+ %add = or i64 %shl, %conv
+ ret i64 %add
+}
+
Added: llvm/trunk/test/Transforms/LoadCombine/load-combine-assume.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoadCombine/load-combine-assume.ll?rev=221203&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoadCombine/load-combine-assume.ll (added)
+++ llvm/trunk/test/Transforms/LoadCombine/load-combine-assume.ll Mon Nov 3 17:19:16 2014
@@ -0,0 +1,44 @@
+; RUN: opt -basicaa -load-combine -instcombine -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @llvm.assume(i1) nounwind
+
+; 'load' before the 'call' gets optimized:
+define i64 @test1(i32* nocapture readonly %a, i1 %b) {
+; CHECK-LABEL: @test1
+
+; CHECK-DAG: load i64* %1, align 4
+; CHECK-DAG: tail call void @llvm.assume(i1 %b)
+; CHECK: ret i64
+
+ %load1 = load i32* %a, align 4
+ %conv = zext i32 %load1 to i64
+ %arrayidx1 = getelementptr inbounds i32* %a, i64 1
+ %load2 = load i32* %arrayidx1, align 4
+ tail call void @llvm.assume(i1 %b)
+ %conv2 = zext i32 %load2 to i64
+ %shl = shl nuw i64 %conv2, 32
+ %add = or i64 %shl, %conv
+ ret i64 %add
+}
+
+; 'call' before the 'load' doesn't get optimized:
+define i64 @test2(i32* nocapture readonly %a, i1 %b) {
+; CHECK-LABEL: @test2
+
+; CHECK-DAG: load i64* %1, align 4
+; CHECK-DAG: tail call void @llvm.assume(i1 %b)
+; CHECK: ret i64
+
+ %load1 = load i32* %a, align 4
+ %conv = zext i32 %load1 to i64
+ %arrayidx1 = getelementptr inbounds i32* %a, i64 1
+ tail call void @llvm.assume(i1 %b)
+ %load2 = load i32* %arrayidx1, align 4
+ %conv2 = zext i32 %load2 to i64
+ %shl = shl nuw i64 %conv2, 32
+ %add = or i64 %shl, %conv
+ ret i64 %add
+}
+
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