285 lines
11 KiB
C++
285 lines
11 KiB
C++
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//===- DDGTest.cpp - DDGAnalysis unit tests -------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/DDG.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/BasicAliasAnalysis.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/AsmParser/Parser.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/Support/SourceMgr.h"
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#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.
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static void runTest(Module &M, StringRef FuncName,
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function_ref<void(Function &F, LoopInfo &LI,
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DependenceInfo &DI, ScalarEvolution &SE)>
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Test) {
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auto *F = M.getFunction(FuncName);
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ASSERT_NE(F, nullptr) << "Could not find " << FuncName;
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TargetLibraryInfoImpl TLII;
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TargetLibraryInfo TLI(TLII);
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AssumptionCache AC(*F);
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DominatorTree DT(*F);
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LoopInfo LI(DT);
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ScalarEvolution SE(*F, TLI, AC, DT, LI);
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AAResults AA(TLI);
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DependenceInfo DI(F, &AA, &SE, &LI);
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Test(*F, LI, DI, SE);
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}
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static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
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const char *ModuleStr) {
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SMDiagnostic Err;
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return parseAssemblyString(ModuleStr, Err, Context);
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}
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TEST(DDGTest, getDependencies) {
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const char *ModuleStr =
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"target datalayout = \"e-m:e-i64:64-n32:64\"\n"
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"target triple = \"powerpc64le-unknown-linux-gnu\"\n"
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"\n"
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"define dso_local void @foo(i32 signext %n, i32* noalias %A, i32* "
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"noalias %B) {\n"
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"entry:\n"
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" %cmp1 = icmp sgt i32 %n, 0\n"
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" br i1 %cmp1, label %for.body.preheader, label %for.end\n"
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"\n"
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"for.body.preheader:\n"
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" %wide.trip.count = zext i32 %n to i64\n"
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" br label %for.body\n"
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" \n"
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" for.body:\n"
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" %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ "
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"%indvars.iv.next, %for.body ]\n"
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" %arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv\n"
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" %0 = trunc i64 %indvars.iv to i32\n"
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" store i32 %0, i32* %arrayidx, align 4\n"
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" %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1\n"
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" %arrayidx2 = getelementptr inbounds i32, i32* %A, i64 "
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"%indvars.iv.next\n"
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" %1 = load i32, i32* %arrayidx2, align 4\n"
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" %add3 = add nsw i32 %1, 1\n"
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" %arrayidx5 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv\n"
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" store i32 %add3, i32* %arrayidx5, align 4\n"
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" %exitcond = icmp ne i64 %indvars.iv.next, %wide.trip.count\n"
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" br i1 %exitcond, label %for.body, label %for.end.loopexit\n"
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"\n"
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"for.end.loopexit:\n"
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" br label %for.end\n"
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"\n"
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"for.end:\n"
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" ret void\n"
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"}\n";
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LLVMContext Context;
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std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);
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runTest(
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*M, "foo",
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[&](Function &F, LoopInfo &LI, DependenceInfo &DI, ScalarEvolution &SE) {
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Loop *L = *LI.begin();
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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
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// while collecting all memory edges as well. There should
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// only be one node with an outgoing memory edge and there
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// should only be one memory edge in the entire graph.
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std::vector<DDGNode *> DependenceSourceNodes;
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std::vector<DDGEdge *> MemoryEdges;
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for (DDGNode *N : DDG) {
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for (DDGEdge *E : *N) {
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bool SourceAdded = false;
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if (E->isMemoryDependence()) {
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MemoryEdges.push_back(E);
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if (!SourceAdded) {
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DependenceSourceNodes.push_back(N);
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SourceAdded = true;
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}
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}
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}
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}
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EXPECT_EQ(DependenceSourceNodes.size(), 1ull);
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EXPECT_EQ(MemoryEdges.size(), 1ull);
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DataDependenceGraph::DependenceList DL;
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DDG.getDependencies(*DependenceSourceNodes.back(),
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MemoryEdges.back()->getTargetNode(), DL);
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EXPECT_EQ(DL.size(), 1ull);
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EXPECT_TRUE(DL.back()->isAnti());
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EXPECT_EQ(DL.back()->getLevels(), 1u);
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EXPECT_NE(DL.back()->getDistance(1), nullptr);
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EXPECT_EQ(DL.back()->getDistance(1),
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SE.getOne(DL.back()->getDistance(1)->getType()));
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});
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}
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/// Test to make sure that when pi-blocks are formed, multiple edges of the same
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/// kind and direction are collapsed into a single edge.
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/// In the test below, %loadASubI belongs to an outside node, which has input
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/// dependency with multiple load instructions in the pi-block containing
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/// %loadBSubI. We expect a single memory dependence edge from the outside node
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/// to this pi-block. The pi-block also contains %add and %add7 both of which
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/// feed a phi in an outside node. We expect a single def-use edge from the
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/// pi-block to the node containing that phi.
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TEST(DDGTest, avoidDuplicateEdgesToFromPiBlocks) {
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const char *ModuleStr =
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"target datalayout = \"e-m:e-i64:64-n32:64-v256:256:256-v512:512:512\"\n"
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"\n"
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"define void @foo(float* noalias %A, float* noalias %B, float* noalias "
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"%C, float* noalias %D, i32 signext %n) {\n"
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"entry:\n"
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" %cmp1 = icmp sgt i32 %n, 0\n"
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" br i1 %cmp1, label %for.body.preheader, label %for.end\n"
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"\n"
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"for.body.preheader: ; preds = %entry\n"
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" %wide.trip.count = zext i32 %n to i64\n"
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" br label %for.body\n"
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"\n"
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"for.body: ; preds = "
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"%for.body.preheader, %if.end\n"
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" %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, "
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"%if.end ]\n"
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" %arrayidx = getelementptr inbounds float, float* %A, i64 %indvars.iv\n"
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" %loadASubI = load float, float* %arrayidx, align 4\n"
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" %arrayidx2 = getelementptr inbounds float, float* %B, i64 "
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"%indvars.iv\n"
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" %loadBSubI = load float, float* %arrayidx2, align 4\n"
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" %add = fadd fast float %loadASubI, %loadBSubI\n"
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" %arrayidx4 = getelementptr inbounds float, float* %A, i64 "
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"%indvars.iv\n"
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" store float %add, float* %arrayidx4, align 4\n"
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" %arrayidx6 = getelementptr inbounds float, float* %A, i64 "
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"%indvars.iv\n"
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" %0 = load float, float* %arrayidx6, align 4\n"
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" %add7 = fadd fast float %0, 1.000000e+00\n"
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" %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1\n"
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" %arrayidx10 = getelementptr inbounds float, float* %B, i64 "
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"%indvars.iv.next\n"
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" store float %add7, float* %arrayidx10, align 4\n"
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" %arrayidx12 = getelementptr inbounds float, float* %A, i64 "
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"%indvars.iv\n"
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" %1 = load float, float* %arrayidx12, align 4\n"
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" %cmp13 = fcmp fast ogt float %1, 1.000000e+02\n"
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" br i1 %cmp13, label %if.then, label %if.else\n"
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"\n"
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"if.then: ; preds = %for.body\n"
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" br label %if.end\n"
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"\n"
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"if.else: ; preds = %for.body\n"
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" br label %if.end\n"
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"\n"
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"if.end: ; preds = %if.else, "
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"%if.then\n"
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" %ff.0 = phi float [ %add, %if.then ], [ %add7, %if.else ]\n"
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" store float %ff.0, float* %C, align 4\n"
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" %exitcond = icmp ne i64 %indvars.iv.next, %wide.trip.count\n"
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" br i1 %exitcond, label %for.body, label %for.end.loopexit\n"
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"\n"
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"for.end.loopexit: ; preds = %if.end\n"
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" br label %for.end\n"
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"\n"
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"for.end: ; preds = "
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"%for.end.loopexit, %entry\n"
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" ret void\n"
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"}\n";
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LLVMContext Context;
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std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);
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runTest(
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*M, "foo",
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[&](Function &F, LoopInfo &LI, DependenceInfo &DI, ScalarEvolution &SE) {
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Loop *L = *LI.begin();
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assert(L && "expected the loop to be identified.");
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DataDependenceGraph DDG(*L, LI, DI);
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const DDGNode *LoadASubI = nullptr;
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for (DDGNode *N : DDG) {
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if (!isa<SimpleDDGNode>(N))
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continue;
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SmallVector<Instruction *, 8> IList;
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N->collectInstructions([](const Instruction *I) { return true; },
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IList);
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if (llvm::any_of(IList, [](Instruction *I) {
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return I->getName() == "loadASubI";
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})) {
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LoadASubI = N;
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break;
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}
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}
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assert(LoadASubI && "Did not find load of A[i]");
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const PiBlockDDGNode *PiBlockWithBSubI = nullptr;
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for (DDGNode *N : DDG) {
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if (!isa<PiBlockDDGNode>(N))
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continue;
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for (DDGNode *M : cast<PiBlockDDGNode>(N)->getNodes()) {
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SmallVector<Instruction *, 8> IList;
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M->collectInstructions([](const Instruction *I) { return true; },
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IList);
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if (llvm::any_of(IList, [](Instruction *I) {
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return I->getName() == "loadBSubI";
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})) {
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PiBlockWithBSubI = static_cast<PiBlockDDGNode *>(N);
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break;
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}
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}
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if (PiBlockWithBSubI)
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break;
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}
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assert(PiBlockWithBSubI &&
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"Did not find pi-block containing load of B[i]");
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const DDGNode *FFPhi = nullptr;
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for (DDGNode *N : DDG) {
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if (!isa<SimpleDDGNode>(N))
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continue;
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SmallVector<Instruction *, 8> IList;
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N->collectInstructions([](const Instruction *I) { return true; },
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IList);
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if (llvm::any_of(IList, [](Instruction *I) {
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return I->getName() == "ff.0";
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})) {
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FFPhi = N;
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break;
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}
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}
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assert(FFPhi && "Did not find ff.0 phi instruction");
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// Expect a single memory edge from '%0 = A[i]' to the pi-block. This
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// means the duplicate incoming memory edges are removed during pi-block
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// formation.
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SmallVector<DDGEdge *, 4> EL;
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LoadASubI->findEdgesTo(*PiBlockWithBSubI, EL);
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unsigned NumMemoryEdges = llvm::count_if(
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EL, [](DDGEdge *Edge) { return Edge->isMemoryDependence(); });
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EXPECT_EQ(NumMemoryEdges, 1ull);
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/// Expect a single def-use edge from the pi-block to '%ff.0 = phi...`.
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/// This means the duplicate outgoing def-use edges are removed during
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/// pi-block formation.
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EL.clear();
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PiBlockWithBSubI->findEdgesTo(*FFPhi, EL);
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NumMemoryEdges =
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llvm::count_if(EL, [](DDGEdge *Edge) { return Edge->isDefUse(); });
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EXPECT_EQ(NumMemoryEdges, 1ull);
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});
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}
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