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[DDG] Data Dependence Graph - Add query function for memory dependenc…
…ies between two nodes Summary: When working with the DDG it's useful to be able to query details of the memory dependencies between two nodes connected by a memory edge. The DDG does not hold a copy of the dependencies, but it contains a reference to a DependenceInfo object through which dependence information can be queried. This patch adds a query function to the DDG to obtain all the Dependence objects that exist between instructions of two nodes. Authored By: bmahjour Reviewers: Meinersbur, Whitney, etiotto Reviewed By: Whitney Tags: #llvm Differential Revision: https://reviews.llvm.org/D80529
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//===- DDGTest.cpp - DDGAnalysis unit tests -------------------------------===// | ||
// | ||
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
// See https://llvm.org/LICENSE.txt for license information. | ||
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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#include "llvm/Analysis/DDG.h" | ||
#include "llvm/Analysis/AliasAnalysis.h" | ||
#include "llvm/Analysis/BasicAliasAnalysis.h" | ||
#include "llvm/Analysis/ScalarEvolution.h" | ||
#include "llvm/Analysis/TargetLibraryInfo.h" | ||
#include "llvm/AsmParser/Parser.h" | ||
#include "llvm/IR/Dominators.h" | ||
#include "llvm/Support/SourceMgr.h" | ||
#include "gtest/gtest.h" | ||
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using namespace llvm; | ||
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/// Build the DDG analysis for a loop and run the given test \p Test. | ||
static void runTest(Module &M, StringRef FuncName, | ||
function_ref<void(Function &F, LoopInfo &LI, | ||
DependenceInfo &DI, ScalarEvolution &SE)> | ||
Test) { | ||
auto *F = M.getFunction(FuncName); | ||
ASSERT_NE(F, nullptr) << "Could not find " << FuncName; | ||
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TargetLibraryInfoImpl TLII; | ||
TargetLibraryInfo TLI(TLII); | ||
AssumptionCache AC(*F); | ||
DominatorTree DT(*F); | ||
LoopInfo LI(DT); | ||
ScalarEvolution SE(*F, TLI, AC, DT, LI); | ||
AAResults AA(TLI); | ||
DependenceInfo DI(F, &AA, &SE, &LI); | ||
Test(*F, LI, DI, SE); | ||
} | ||
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static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context, | ||
const char *ModuleStr) { | ||
SMDiagnostic Err; | ||
return parseAssemblyString(ModuleStr, Err, Context); | ||
} | ||
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TEST(DDGTest, getDependencies) { | ||
const char *ModuleStr = | ||
"target datalayout = \"e-m:e-i64:64-n32:64\"\n" | ||
"target triple = \"powerpc64le-unknown-linux-gnu\"\n" | ||
"\n" | ||
"define dso_local void @foo(i32 signext %n, i32* noalias %A, i32* " | ||
"noalias %B) {\n" | ||
"entry:\n" | ||
" %cmp1 = icmp sgt i32 %n, 0\n" | ||
" br i1 %cmp1, label %for.body.preheader, label %for.end\n" | ||
"\n" | ||
"for.body.preheader:\n" | ||
" %wide.trip.count = zext i32 %n to i64\n" | ||
" br label %for.body\n" | ||
" \n" | ||
" for.body:\n" | ||
" %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ " | ||
"%indvars.iv.next, %for.body ]\n" | ||
" %arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv\n" | ||
" %0 = trunc i64 %indvars.iv to i32\n" | ||
" store i32 %0, i32* %arrayidx, align 4\n" | ||
" %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1\n" | ||
" %arrayidx2 = getelementptr inbounds i32, i32* %A, i64 " | ||
"%indvars.iv.next\n" | ||
" %1 = load i32, i32* %arrayidx2, align 4\n" | ||
" %add3 = add nsw i32 %1, 1\n" | ||
" %arrayidx5 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv\n" | ||
" store i32 %add3, i32* %arrayidx5, align 4\n" | ||
" %exitcond = icmp ne i64 %indvars.iv.next, %wide.trip.count\n" | ||
" br i1 %exitcond, label %for.body, label %for.end.loopexit\n" | ||
"\n" | ||
"for.end.loopexit:\n" | ||
" br label %for.end\n" | ||
"\n" | ||
"for.end:\n" | ||
" ret void\n" | ||
"}\n"; | ||
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LLVMContext Context; | ||
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr); | ||
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runTest( | ||
*M, "foo", | ||
[&](Function &F, LoopInfo &LI, DependenceInfo &DI, ScalarEvolution &SE) { | ||
Loop *L = *LI.begin(); | ||
assert(L && "expected the loop to be identified."); | ||
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DataDependenceGraph DDG(*L, LI, DI); | ||
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// Collect all the nodes that have an outgoing memory edge | ||
// while collecting all memory edges as well. There should | ||
// only be one node with an outgoing memory edge and there | ||
// should only be one memory edge in the entire graph. | ||
std::vector<DDGNode *> DependenceSourceNodes; | ||
std::vector<DDGEdge *> MemoryEdges; | ||
for (DDGNode *N : DDG) { | ||
for (DDGEdge *E : *N) { | ||
bool SourceAdded = false; | ||
if (E->isMemoryDependence()) { | ||
MemoryEdges.push_back(E); | ||
if (!SourceAdded) { | ||
DependenceSourceNodes.push_back(N); | ||
SourceAdded = true; | ||
} | ||
} | ||
} | ||
} | ||
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EXPECT_EQ(DependenceSourceNodes.size(), 1ull); | ||
EXPECT_EQ(MemoryEdges.size(), 1ull); | ||
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DataDependenceGraph::DependenceList DL; | ||
DDG.getDependencies(*DependenceSourceNodes.back(), | ||
MemoryEdges.back()->getTargetNode(), DL); | ||
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EXPECT_EQ(DL.size(), 1ull); | ||
EXPECT_TRUE(DL.back()->isAnti()); | ||
EXPECT_EQ(DL.back()->getLevels(), 1u); | ||
EXPECT_NE(DL.back()->getDistance(1), nullptr); | ||
EXPECT_EQ(DL.back()->getDistance(1), | ||
SE.getOne(DL.back()->getDistance(1)->getType())); | ||
}); | ||
} |