[DirectX] initialize registers properties by calling addRegisterClass and computeRegisterProperties

[farzonl]

This fixes #126784 for the DirectX backend.
This bug was marked critical for DX so it is going to go in first. At least one register class needs to be added via addRegisterClass for RegClassForVT to be valid.
Further for costing information used by loop unroll and other optimizations to be valid we need to call computeRegisterProperties. This change does both of these.

The test cases confirm that we can fetch costing information off of getRegisterInfo and that DirectXTargetLowering maps i32 typed registers to DXILClassRegClass.

[llvmbot]

@llvm/pr-subscribers-backend-directx

Author: Farzon Lotfi (farzonl)

Changes

This fixes #126784 for the DirectX backend.
This bug was marked critical for DX so it is going to go in first. At least one register class needs to be added via addRegisterClass for RegClassForVT to be valid.
Further for costing information used by loop unroll and other optimizations to be valid we need to call computeRegisterProperties. This change does both of these.

The test cases confirm that we can fetch costing information off of getRegisterInfo and that DirectXTargetLowering maps i32 typed registers to DXILClassRegClass.

---

Full diff: https://github.com/llvm/llvm-project/pull/128818.diff

3 Files Affected:

• (modified) llvm/lib/Target/DirectX/DirectXTargetMachine.cpp (+4-1)
• (modified) llvm/unittests/Target/DirectX/CMakeLists.txt (+1)
• (added) llvm/unittests/Target/DirectX/RegisterCostTests.cpp (+65)

diff --git a/llvm/lib/Target/DirectX/DirectXTargetMachine.cpp b/llvm/lib/Target/DirectX/DirectXTargetMachine.cpp
index a76c07f784177..dda650b0f6e15 100644
--- a/llvm/lib/Target/DirectX/DirectXTargetMachine.cpp
+++ b/llvm/lib/Target/DirectX/DirectXTargetMachine.cpp
@@ -187,4 +187,7 @@ DirectXTargetMachine::getTargetTransformInfo(const Function &F) const {
 
 DirectXTargetLowering::DirectXTargetLowering(const DirectXTargetMachine &TM,
                                              const DirectXSubtarget &STI)
-    : TargetLowering(TM) {}
+    : TargetLowering(TM) {
+  addRegisterClass(MVT::i32, &dxil::DXILClassRegClass);
+  computeRegisterProperties(STI.getRegisterInfo());
+}
diff --git a/llvm/unittests/Target/DirectX/CMakeLists.txt b/llvm/unittests/Target/DirectX/CMakeLists.txt
index fd0d5a0dd52c1..5087727ff9800 100644
--- a/llvm/unittests/Target/DirectX/CMakeLists.txt
+++ b/llvm/unittests/Target/DirectX/CMakeLists.txt
@@ -16,4 +16,5 @@ add_llvm_target_unittest(DirectXTests
   CBufferDataLayoutTests.cpp
   PointerTypeAnalysisTests.cpp
   UniqueResourceFromUseTests.cpp
+  RegisterCostTests.cpp
   )
diff --git a/llvm/unittests/Target/DirectX/RegisterCostTests.cpp b/llvm/unittests/Target/DirectX/RegisterCostTests.cpp
new file mode 100644
index 0000000000000..ebf740ed73e98
--- /dev/null
+++ b/llvm/unittests/Target/DirectX/RegisterCostTests.cpp
@@ -0,0 +1,65 @@
+//===- llvm/unittests/Target/DirectX/RegisterCostTests.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 "DirectXInstrInfo.h"
+#include "DirectXTargetLowering.h"
+#include "DirectXTargetMachine.h"
+#include "TargetInfo/DirectXTargetInfo.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/MC/MCTargetOptions.h"
+#include "llvm/MC/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::dxil;
+
+namespace {
+class RegisterCostTests : public testing::Test {
+protected:
+  DirectXInstrInfo DXInstInfo;
+  DirectXRegisterInfo RI;
+  DirectXTargetLowering *DL;
+
+  virtual void SetUp() {
+    LLVMInitializeDirectXTargetMC();
+    Target T = getTheDirectXTarget();
+    RegisterTargetMachine<DirectXTargetMachine> X(T);
+    Triple TT("dxil-pc-shadermodel6.3-library");
+    StringRef CPU = "";
+    StringRef FS = "";
+    DirectXTargetMachine TM(T, TT, CPU, FS, TargetOptions(), Reloc::Static,
+                            CodeModel::Small, CodeGenOptLevel::Default, false);
+    LLVMContext Context;
+    Function *F =
+        Function::Create(FunctionType::get(Type::getVoidTy(Context), false),
+                         Function::ExternalLinkage, 0);
+    DL = new DirectXTargetLowering(TM, *TM.getSubtargetImpl(*F));
+    delete F;
+  }
+  virtual void TearDown() { delete DL; }
+};
+
+TEST_F(RegisterCostTests, TestRepRegClassForVTSet) {
+  const TargetRegisterClass *RC = DL->getRepRegClassFor(MVT::i32);
+  EXPECT_EQ(&dxil::DXILClassRegClass, RC);
+}
+
+TEST_F(RegisterCostTests, TestTrivialCopyCostGetter) {
+
+  const TargetRegisterClass *RC = DXInstInfo.getRegisterInfo().getRegClass(0);
+  unsigned Cost = RC->getCopyCost();
+  EXPECT_EQ(1u, Cost);
+
+  RC = RI.getRegClass(0);
+  Cost = RC->getCopyCost();
+  EXPECT_EQ(1u, Cost);
+}
+} // namespace

[joaosaffran]

LGTM

[farzonl]

DirectXTargetLowering does not expose DirectXRegisterInfo so just testing it seperately to confirm we can fetch costing data off of it.

[llvm-ci]

LLVM Buildbot has detected a new failure on builder lld-x86_64-win running on as-worker-93 while building llvm at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/146/builds/2371

Here is the relevant piece of the build log for the reference

Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM-Unit :: Support/./SupportTests.exe/38/87' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:C:\a\lld-x86_64-win\build\unittests\Support\.\SupportTests.exe-LLVM-Unit-15220-38-87.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=87 GTEST_SHARD_INDEX=38 C:\a\lld-x86_64-win\build\unittests\Support\.\SupportTests.exe
--

Script:
--
C:\a\lld-x86_64-win\build\unittests\Support\.\SupportTests.exe --gtest_filter=ProgramEnvTest.CreateProcessLongPath
--
C:\a\lld-x86_64-win\llvm-project\llvm\unittests\Support\ProgramTest.cpp(160): error: Expected equality of these values:
  0
  RC
    Which is: -2

C:\a\lld-x86_64-win\llvm-project\llvm\unittests\Support\ProgramTest.cpp(163): error: fs::remove(Twine(LongPath)): did not return errc::success.
error number: 13
error message: permission denied



C:\a\lld-x86_64-win\llvm-project\llvm\unittests\Support\ProgramTest.cpp:160
Expected equality of these values:
  0
  RC
    Which is: -2

C:\a\lld-x86_64-win\llvm-project\llvm\unittests\Support\ProgramTest.cpp:163
fs::remove(Twine(LongPath)): did not return errc::success.
error number: 13
error message: permission denied




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