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LegalizerTest.cpp
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//===- LegalizerTest.cpp --------------------------------------------------===//
//
// 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/CodeGen/GlobalISel/Legalizer.h"
#include "GISelMITest.h"
#include "llvm/CodeGen/GlobalISel/LostDebugLocObserver.h"
#define DEBUG_TYPE "legalizer-test"
using namespace LegalizeActions;
using namespace LegalizeMutations;
using namespace LegalityPredicates;
namespace {
::testing::AssertionResult isNullMIPtr(const MachineInstr *MI) {
if (MI == nullptr)
return ::testing::AssertionSuccess();
std::string MIBuffer;
raw_string_ostream MISStream(MIBuffer);
MI->print(MISStream, /*IsStandalone=*/true, /*SkipOpers=*/false,
/*SkipDebugLoc=*/false, /*AddNewLine=*/false);
return ::testing::AssertionFailure()
<< "unable to legalize instruction: " << MISStream.str();
}
DefineLegalizerInfo(ALegalizer, {
auto p0 = LLT::pointer(0, 64);
auto s8 = LLT::scalar(8);
auto v2s8 = LLT::fixed_vector(2, 8);
auto v2s16 = LLT::fixed_vector(2, 16);
getActionDefinitionsBuilder(G_LOAD)
.legalForTypesWithMemDesc({{s16, p0, s8, 8}})
.scalarize(0)
.clampScalar(0, s16, s16);
getActionDefinitionsBuilder(G_PTR_ADD).legalFor({{p0, s64}});
getActionDefinitionsBuilder(G_CONSTANT).legalFor({s32, s64});
getActionDefinitionsBuilder(G_BUILD_VECTOR)
.legalFor({{v2s16, s16}})
.clampScalar(1, s16, s16);
getActionDefinitionsBuilder(G_BUILD_VECTOR_TRUNC).legalFor({{v2s8, s16}});
getActionDefinitionsBuilder(G_ANYEXT).legalFor({{s32, s16}});
getActionDefinitionsBuilder(G_ZEXT).legalFor({{s32, s16}});
getActionDefinitionsBuilder(G_SEXT).legalFor({{s32, s16}});
getActionDefinitionsBuilder(G_AND).legalFor({s32});
getActionDefinitionsBuilder(G_SEXT_INREG).lower();
getActionDefinitionsBuilder(G_ASHR).legalFor({{s32, s32}});
getActionDefinitionsBuilder(G_SHL).legalFor({{s32, s32}});
})
TEST_F(AArch64GISelMITest, BasicLegalizerTest) {
StringRef MIRString = R"(
%vptr:_(p0) = COPY $x4
%v:_(<2 x s8>) = G_LOAD %vptr:_(p0) :: (load (<2 x s8>), align 1)
$h4 = COPY %v:_(<2 x s8>)
)";
setUp(MIRString.rtrim(' '));
if (!TM)
return;
ALegalizerInfo LI(MF->getSubtarget());
LostDebugLocObserver LocObserver(DEBUG_TYPE);
Legalizer::MFResult Result = Legalizer::legalizeMachineFunction(
*MF, LI, {&LocObserver}, LocObserver, B);
EXPECT_TRUE(isNullMIPtr(Result.FailedOn));
EXPECT_TRUE(Result.Changed);
StringRef CheckString = R"(
CHECK: %vptr:_(p0) = COPY $x4
CHECK-NEXT: [[LOAD_0:%[0-9]+]]:_(s16) = G_LOAD %vptr:_(p0) :: (load (s8))
CHECK-NEXT: [[OFFSET_1:%[0-9]+]]:_(s64) = G_CONSTANT i64 1
CHECK-NEXT: [[VPTR_1:%[0-9]+]]:_(p0) = G_PTR_ADD %vptr:_, [[OFFSET_1]]:_(s64)
CHECK-NEXT: [[LOAD_1:%[0-9]+]]:_(s16) = G_LOAD [[VPTR_1]]:_(p0) :: (load (s8) from unknown-address + 1)
CHECK-NEXT: %v:_(<2 x s8>) = G_BUILD_VECTOR_TRUNC [[LOAD_0]]:_(s16), [[LOAD_1]]:_(s16)
CHECK-NEXT: $h4 = COPY %v:_(<2 x s8>)
)";
EXPECT_TRUE(CheckMachineFunction(*MF, CheckString)) << *MF;
}
// Making sure the legalization finishes successfully w/o failure to combine
// away all the legalization artifacts regardless of the order of their
// creation.
TEST_F(AArch64GISelMITest, UnorderedArtifactCombiningTest) {
StringRef MIRString = R"(
%vptr:_(p0) = COPY $x4
%v:_(<2 x s8>) = G_LOAD %vptr:_(p0) :: (load (<2 x s8>), align 1)
%v0:_(s8), %v1:_(s8) = G_UNMERGE_VALUES %v:_(<2 x s8>)
%v0_ext:_(s16) = G_ANYEXT %v0:_(s8)
$h4 = COPY %v0_ext:_(s16)
)";
setUp(MIRString.rtrim(' '));
if (!TM)
return;
ALegalizerInfo LI(MF->getSubtarget());
LostDebugLocObserver LocObserver(DEBUG_TYPE);
// The events here unfold as follows:
// 1. First, the function is scanned pre-forming the worklist of artifacts:
//
// UNMERGE (1): pushed into the worklist first, will be processed last.
// |
// ANYEXT (2)
//
// 2. Second, the load is scalarized, and then its destination is widened,
// forming the following chain of legalization artifacts:
//
// TRUNC (4): created last, will be processed first.
// |
// BUILD_VECTOR (3)
// |
// UNMERGE (1): pushed into the worklist first, will be processed last.
// |
// ANYEXT (2)
//
// 3. Third, the artifacts are attempted to be combined in pairs, looking
// through the def-use chain from the roots towards the leafs, visiting the
// roots in order they happen to be in the worklist:
// (4) - (trunc): can not be combined;
// (3) - (build_vector (trunc)): can not be combined;
// (2) - (anyext (unmerge)): can not be combined;
// (1) - (unmerge (build_vector)): combined and eliminated;
//
// leaving the function in the following state:
//
// TRUNC (1): moved to non-artifact instructions worklist first.
// |
// ANYEXT (2): also moved to non-artifact instructions worklist.
//
// Every other instruction is successfully legalized in full.
// If combining (unmerge (build_vector)) does not re-insert every artifact
// that had its def-use chain modified (shortened) into the artifact
// worklist (here it's just ANYEXT), the process moves on onto the next
// outer loop iteration of the top-level legalization algorithm here, w/o
// performing all the artifact combines possible. Let's consider this
// scenario first:
// 4.A. Neither TRUNC, nor ANYEXT can be legalized in isolation, both of them
// get moved to the retry worklist, but no additional artifacts were
// created in the process, thus algorithm concludes no progress could be
// made, and fails.
// 4.B. If, however, combining (unmerge (build_vector)) had re-inserted
// ANYEXT into the worklist (as ANYEXT's source changes, not by value,
// but by implementation), (anyext (trunc)) combine happens next, which
// fully eliminates all the artifacts and legalization succeeds.
//
// We're looking into making sure that (4.B) happens here, not (4.A). Note
// that in that case the first scan through the artifacts worklist, while not
// being done in any guaranteed order, only needs to find the innermost
// pair(s) of artifacts that could be immediately combined out. After that
// the process follows def-use chains, making them shorter at each step, thus
// combining everything that can be combined in O(n) time.
Legalizer::MFResult Result = Legalizer::legalizeMachineFunction(
*MF, LI, {&LocObserver}, LocObserver, B);
EXPECT_TRUE(isNullMIPtr(Result.FailedOn));
EXPECT_TRUE(Result.Changed);
StringRef CheckString = R"(
CHECK: %vptr:_(p0) = COPY $x4
CHECK-NEXT: [[LOAD_0:%[0-9]+]]:_(s16) = G_LOAD %vptr:_(p0) :: (load (s8))
CHECK: $h4 = COPY [[LOAD_0]]:_(s16)
)";
EXPECT_TRUE(CheckMachineFunction(*MF, CheckString)) << *MF;
}
TEST_F(AArch64GISelMITest, UnorderedArtifactCombiningManyCopiesTest) {
StringRef MIRString = R"(
%vptr:_(p0) = COPY $x4
%v:_(<2 x s8>) = G_LOAD %vptr:_(p0) :: (load (<2 x s8>), align 1)
%vc0:_(<2 x s8>) = COPY %v:_(<2 x s8>)
%vc1:_(<2 x s8>) = COPY %v:_(<2 x s8>)
%vc00:_(s8), %vc01:_(s8) = G_UNMERGE_VALUES %vc0:_(<2 x s8>)
%vc10:_(s8), %vc11:_(s8) = G_UNMERGE_VALUES %vc1:_(<2 x s8>)
%v0t:_(s8) = COPY %vc00:_(s8)
%v0:_(s8) = COPY %v0t:_(s8)
%v1t:_(s8) = COPY %vc11:_(s8)
%v1:_(s8) = COPY %v1t:_(s8)
%v0_zext:_(s32) = G_ZEXT %v0:_(s8)
%v1_sext:_(s32) = G_SEXT %v1:_(s8)
$w4 = COPY %v0_zext:_(s32)
$w5 = COPY %v1_sext:_(s32)
)";
setUp(MIRString.rtrim(' '));
if (!TM)
return;
ALegalizerInfo LI(MF->getSubtarget());
LostDebugLocObserver LocObserver(DEBUG_TYPE);
Legalizer::MFResult Result = Legalizer::legalizeMachineFunction(
*MF, LI, {&LocObserver}, LocObserver, B);
EXPECT_TRUE(isNullMIPtr(Result.FailedOn));
EXPECT_TRUE(Result.Changed);
StringRef CheckString = R"(
CHECK: %vptr:_(p0) = COPY $x4
CHECK-NEXT: [[LOAD_0:%[0-9]+]]:_(s16) = G_LOAD %vptr:_(p0) :: (load (s8))
CHECK-NEXT: [[OFFSET_1:%[0-9]+]]:_(s64) = G_CONSTANT i64 1
CHECK-NEXT: [[VPTR_1:%[0-9]+]]:_(p0) = G_PTR_ADD %vptr:_, [[OFFSET_1]]:_(s64)
CHECK-NEXT: [[LOAD_1:%[0-9]+]]:_(s16) = G_LOAD [[VPTR_1]]:_(p0) :: (load (s8) from unknown-address + 1)
CHECK-NEXT: [[FF_MASK:%[0-9]+]]:_(s32) = G_CONSTANT i32 255
CHECK-NEXT: [[V0_EXT:%[0-9]+]]:_(s32) = G_ANYEXT [[LOAD_0]]:_(s16)
CHECK-NEXT: %v0_zext:_(s32) = G_AND [[V0_EXT]]:_, [[FF_MASK]]:_
CHECK-NEXT: [[V1_EXT:%[0-9]+]]:_(s32) = G_ANYEXT [[LOAD_1]]:_(s16)
CHECK-NEXT: [[SHAMNT:%[0-9]+]]:_(s32) = G_CONSTANT i32 24
CHECK-NEXT: [[V1_SHL:%[0-9]+]]:_(s32) = G_SHL [[V1_EXT]]:_, [[SHAMNT]]:_(s32)
CHECK-NEXT: %v1_sext:_(s32) = G_ASHR [[V1_SHL]]:_, [[SHAMNT]]:_(s32)
CHECK-NEXT: $w4 = COPY %v0_zext:_(s32)
CHECK-NEXT: $w5 = COPY %v1_sext:_(s32)
)";
EXPECT_TRUE(CheckMachineFunction(*MF, CheckString)) << *MF;
}
} // namespace