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//===- LoadsTest.cpp - local load analysis 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
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
SMDiagnostic Err;
std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
if (!Mod)
Err.print("AnalysisTests", errs());
return Mod;
}
TEST(LoadsTest, FindAvailableLoadedValueSameBasePtrConstantOffsetsNullAA) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(C,
R"IR(
target datalayout = "p:64:64:64:32"
%class = type <{ i32, i32 }>
define i32 @f() {
entry:
%o = alloca %class
%f1 = getelementptr inbounds %class, %class* %o, i32 0, i32 0
store i32 42, i32* %f1
%f2 = getelementptr inbounds %class, %class* %o, i32 0, i32 1
store i32 43, i32* %f2
%v = load i32, i32* %f1
ret i32 %v
}
)IR");
auto *GV = M->getNamedValue("f");
ASSERT_TRUE(GV);
auto *F = dyn_cast<Function>(GV);
ASSERT_TRUE(F);
Instruction *Inst = &F->front().front();
auto *AI = dyn_cast<AllocaInst>(Inst);
ASSERT_TRUE(AI);
Inst = &*++F->front().rbegin();
auto *LI = dyn_cast<LoadInst>(Inst);
ASSERT_TRUE(LI);
BasicBlock::iterator BBI(LI);
Value *Loaded = FindAvailableLoadedValue(
LI, LI->getParent(), BBI, 0, nullptr, nullptr);
ASSERT_TRUE(Loaded);
auto *CI = dyn_cast<ConstantInt>(Loaded);
ASSERT_TRUE(CI);
ASSERT_TRUE(CI->equalsInt(42));
}
TEST(LoadsTest, CanReplacePointersIfEqual) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(C,
R"IR(
@y = common global [1 x i32] zeroinitializer, align 4
@x = common global [1 x i32] zeroinitializer, align 4
declare void @use(i32*)
define void @f(i32* %p1, i32* %p2, i64 %i) {
call void @use(i32* getelementptr inbounds ([1 x i32], [1 x i32]* @y, i64 0, i64 0))
%p1_idx = getelementptr inbounds i32, i32* %p1, i64 %i
call void @use(i32* %p1_idx)
%icmp = icmp eq i32* %p1, getelementptr inbounds ([1 x i32], [1 x i32]* @y, i64 0, i64 0)
%ptrInt = ptrtoint i32* %p1 to i64
ret void
}
)IR");
const DataLayout &DL = M->getDataLayout();
auto *GV = M->getNamedValue("f");
ASSERT_TRUE(GV);
auto *F = dyn_cast<Function>(GV);
ASSERT_TRUE(F);
Value *P1 = &*F->arg_begin();
Value *P2 = F->getArg(1);
Value *NullPtr = Constant::getNullValue(P1->getType());
auto InstIter = F->front().begin();
CallInst *UserOfY = cast<CallInst>(&*InstIter);
Value *ConstDerefPtr = UserOfY->getArgOperand(0);
// We cannot replace two pointers in arbitrary instructions unless we are
// replacing with null, a constant dereferencable pointer or they have the
// same underlying object.
EXPECT_FALSE(canReplacePointersIfEqual(ConstDerefPtr, P1, DL));
EXPECT_FALSE(canReplacePointersIfEqual(P1, P2, DL));
EXPECT_TRUE(canReplacePointersIfEqual(P1, ConstDerefPtr, DL));
EXPECT_TRUE(canReplacePointersIfEqual(P1, NullPtr, DL));
GetElementPtrInst *BasedOnP1 = cast<GetElementPtrInst>(&*++InstIter);
EXPECT_TRUE(canReplacePointersIfEqual(BasedOnP1, P1, DL));
EXPECT_FALSE(canReplacePointersIfEqual(BasedOnP1, P2, DL));
// We can replace two arbitrary pointers in icmp and ptrtoint instructions.
auto P1UseIter = P1->use_begin();
const Use &PtrToIntUse = *P1UseIter;
const Use &IcmpUse = *++P1UseIter;
const Use &GEPUse = *++P1UseIter;
EXPECT_FALSE(canReplacePointersInUseIfEqual(GEPUse, P2, DL));
EXPECT_TRUE(canReplacePointersInUseIfEqual(PtrToIntUse, P2, DL));
EXPECT_TRUE(canReplacePointersInUseIfEqual(IcmpUse, P2, DL));
}
TEST(LoadsTest, IsDerefReadOnlyLoop) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(C,
R"IR(
define i64 @f1() {
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
define i64 @f2(ptr %p1) {
entry:
%p2 = alloca [1024 x i8]
br label %loop
loop:
%index = phi i64 [ %index.next, %loop.inc ], [ 3, %entry ]
%arrayidx = getelementptr inbounds i8, ptr %p1, i64 %index
%ld1 = load i8, ptr %arrayidx, align 1
%arrayidx1 = getelementptr inbounds i8, ptr %p2, i64 %index
%ld2 = load i8, ptr %arrayidx1, align 1
%cmp3 = icmp eq i8 %ld1, %ld2
br i1 %cmp3, label %loop.inc, label %loop.end
loop.inc:
%index.next = add i64 %index, 1
%exitcond = icmp ne i64 %index.next, 67
br i1 %exitcond, label %loop, label %loop.end
loop.end:
%retval = phi i64 [ %index, %loop ], [ 67, %loop.inc ]
ret i64 %retval
}
)IR");
auto *GV1 = M->getNamedValue("f1");
auto *GV2 = M->getNamedValue("f2");
ASSERT_TRUE(GV1 && GV2);
auto *F1 = dyn_cast<Function>(GV1);
auto *F2 = dyn_cast<Function>(GV2);
ASSERT_TRUE(F1 && F2);
TargetLibraryInfoImpl TLII(M->getTargetTriple());
TargetLibraryInfo TLI(TLII);
auto IsDerefReadOnlyLoop = [&TLI](Function *F) -> bool {
AssumptionCache AC(*F);
DominatorTree DT(*F);
LoopInfo LI(DT);
ScalarEvolution SE(*F, TLI, AC, DT, LI);
Function::iterator FI = F->begin();
// First basic block is entry - skip it.
BasicBlock *Header = &*(++FI);
assert(Header->getName() == "loop");
Loop *L = LI.getLoopFor(Header);
return isDereferenceableReadOnlyLoop(L, &SE, &DT, &AC);
};
ASSERT_TRUE(IsDerefReadOnlyLoop(F1));
ASSERT_FALSE(IsDerefReadOnlyLoop(F2));
}
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