llvm/unittests/Analysis/CaptureTrackingTest.cpp

   1 //=======- CaptureTrackingTest.cpp - Unit test for the Capture Tracking ---===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Analysis/CaptureTracking.h"
  10 #include "llvm/AsmParser/Parser.h"
  11 #include "llvm/IR/Dominators.h"
  12 #include "llvm/IR/Instructions.h"
  13 #include "llvm/IR/LLVMContext.h"
  14 #include "llvm/IR/Module.h"
  15 #include "llvm/Support/SourceMgr.h"
  16 #include "gtest/gtest.h"
  17
  18 using namespace llvm;
  19
  20 TEST(CaptureTracking, MaxUsesToExplore) {
  21   StringRef Assembly = R"(
  22     ; Function Attrs: nounwind ssp uwtable
  23     declare void @doesnt_capture(i8* nocapture, i8* nocapture, i8* nocapture,
  24                                  i8* nocapture, i8* nocapture)
  25
  26     ; %arg has 5 uses
  27     define void @test_few_uses(i8* %arg) {
  28       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  29       ret void
  30     }
  31
  32     ; %arg has 50 uses
  33     define void @test_many_uses(i8* %arg) {
  34       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  35       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  36       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  37       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  38       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  39       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  40       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  41       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  42       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  43       call void @doesnt_capture(i8* %arg, i8* %arg, i8* %arg, i8* %arg, i8* %arg)
  44       ret void
  45     }
  46   )";
  47
  48   LLVMContext Context;
  49   SMDiagnostic Error;
  50   auto M = parseAssemblyString(Assembly, Error, Context);
  51   ASSERT_TRUE(M) << "Bad assembly?";
  52
  53   auto Test = [&M](const char *FName, unsigned FalseMaxUsesLimit,
  54                    unsigned TrueMaxUsesLimit) {
  55     Function *F = M->getFunction(FName);
  56     ASSERT_NE(F, nullptr);
  57     Value *Arg = &*F->arg_begin();
  58     ASSERT_NE(Arg, nullptr);
  59     ASSERT_FALSE(PointerMayBeCaptured(Arg, true, true, FalseMaxUsesLimit));
  60     ASSERT_TRUE(PointerMayBeCaptured(Arg, true, true, TrueMaxUsesLimit));
  61
  62     BasicBlock *EntryBB = &F->getEntryBlock();
  63     DominatorTree DT(*F);
  64
  65     Instruction *Ret = EntryBB->getTerminator();
  66     ASSERT_TRUE(isa<ReturnInst>(Ret));
  67     ASSERT_FALSE(PointerMayBeCapturedBefore(Arg, true, true, Ret, &DT, false,
  68                                             FalseMaxUsesLimit));
  69     ASSERT_TRUE(PointerMayBeCapturedBefore(Arg, true, true, Ret, &DT, false,
  70                                            TrueMaxUsesLimit));
  71   };
  72
  73   Test("test_few_uses", 6, 4);
  74   Test("test_many_uses", 50, 30);
  75 }
  76
  77 struct CollectingCaptureTracker : public CaptureTracker {
  78   SmallVector<const Use *, 4> Captures;
  79   void tooManyUses() override { }
  80   bool captured(const Use *U) override {
  81     Captures.push_back(U);
  82     return false;
  83   }
  84 };
  85
  86 TEST(CaptureTracking, MultipleUsesInSameInstruction) {
  87   StringRef Assembly = R"(
  88     declare void @call(i8*, i8*, i8*)
  89
  90     define void @test(i8* %arg, i8** %ptr) {
  91       call void @call(i8* %arg, i8* nocapture %arg, i8* %arg) [ "bundle"(i8* %arg) ]
  92       cmpxchg i8** %ptr, i8* %arg, i8* %arg acq_rel monotonic
  93       icmp eq i8* %arg, %arg
  94       ret void
  95     }
  96   )";
  97
  98   LLVMContext Context;
  99   SMDiagnostic Error;
 100   auto M = parseAssemblyString(Assembly, Error, Context);
 101   ASSERT_TRUE(M) << "Bad assembly?";
 102
 103   Function *F = M->getFunction("test");
 104   Value *Arg = &*F->arg_begin();
 105   BasicBlock *BB = &F->getEntryBlock();
 106   Instruction *Call = &*BB->begin();
 107   Instruction *CmpXChg = Call->getNextNode();
 108   Instruction *ICmp = CmpXChg->getNextNode();
 109
 110   CollectingCaptureTracker CT;
 111   PointerMayBeCaptured(Arg, &CT);
 112   EXPECT_EQ(7u, CT.Captures.size());
 113   // Call arg 1
 114   EXPECT_EQ(Call, CT.Captures[0]->getUser());
 115   EXPECT_EQ(0u, CT.Captures[0]->getOperandNo());
 116   // Call arg 3
 117   EXPECT_EQ(Call, CT.Captures[1]->getUser());
 118   EXPECT_EQ(2u, CT.Captures[1]->getOperandNo());
 119   // Operand bundle arg
 120   EXPECT_EQ(Call, CT.Captures[2]->getUser());
 121   EXPECT_EQ(3u, CT.Captures[2]->getOperandNo());
 122   // Cmpxchg compare operand
 123   EXPECT_EQ(CmpXChg, CT.Captures[3]->getUser());
 124   EXPECT_EQ(1u, CT.Captures[3]->getOperandNo());
 125   // Cmpxchg new value operand
 126   EXPECT_EQ(CmpXChg, CT.Captures[4]->getUser());
 127   EXPECT_EQ(2u, CT.Captures[4]->getOperandNo());
 128   // ICmp first operand
 129   EXPECT_EQ(ICmp, CT.Captures[5]->getUser());
 130   EXPECT_EQ(0u, CT.Captures[5]->getOperandNo());
 131   // ICmp second operand
 132   EXPECT_EQ(ICmp, CT.Captures[6]->getUser());
 133   EXPECT_EQ(1u, CT.Captures[6]->getOperandNo());
 134 }