[ValueTracking] Make unit tests easier to write; NFC

[nikic]

Summary

This makes unit tests for ValueTracking and in particular computeKnownBits easier to write, by generalizing the existing MatchSelectPatternTest class to also work with other types of tests. It inherits the convention that the function must be @test and the tested instruction %A.

[spatel]

unittests/Analysis/ValueTrackingTest.cpp

61

This shouldn't be duplicated in the base class?

[nikic]

Remove duplicate method.

[nikic]

unittests/Analysis/ValueTrackingTest.cpp

61

Uh, yes, it certainly shouldn't!

[spatel]

LGTM - thanks!

unittests/Analysis/ValueTrackingTest.cpp

 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/KnownBits.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
 
 namespace {
 
-class MatchSelectPatternTest : public testing::Test {
+class ValueTrackingTest : public testing::Test {
 protected:
   void parseAssembly(const char *Assembly) {
     SMDiagnostic Error;
     M = parseAssemblyString(Assembly, Error, Context);
 
     std::string errMsg;
     raw_string_ostream os(errMsg);
     Error.print("", os);
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
         if (I->getName() == "A")
           A = &*I;
       }
     }
     if (A == nullptr)
       report_fatal_error("@test must have an instruction %A");
   }
 
+  LLVMContext Context;
+  std::unique_ptr<Module> M;
+  Instruction *A;
+};
+
+class MatchSelectPatternTest : public ValueTrackingTest {
+protected:
   void expectPattern(const SelectPatternResult &P) {
     Value *LHS, *RHS;
     Instruction::CastOps CastOp;
     SelectPatternResult R = matchSelectPattern(A, LHS, RHS, &CastOp);
     EXPECT_EQ(P.Flavor, R.Flavor);
     EXPECT_EQ(P.NaNBehavior, R.NaNBehavior);
     EXPECT_EQ(P.Ordered, R.Ordered);
   }
+};
 
-  LLVMContext Context;
-  std::unique_ptr<Module> M;
-  Instruction *A, *B;
+class ComputeKnownBitsTest : public ValueTrackingTest {
+protected:
+  void expectKnownBits(uint64_t Zero, uint64_t One) {
+    auto Known = computeKnownBits(A, M->getDataLayout());
+    ASSERT_FALSE(Known.hasConflict());
+    EXPECT_EQ(Known.One.getZExtValue(), One);
+    EXPECT_EQ(Known.Zero.getZExtValue(), Zero);
+  }
 };
 
 }
 
 TEST_F(MatchSelectPatternTest, SimpleFMin) {
   parseAssembly(
       "define float @test(float %a) {\n"
       "  %1 = fcmp ult float %a, 5.0\n"
TEST(ValueTracking, GuaranteedToTransferExecutionToSuccessor) {
   for (auto &I : BB) {
     EXPECT_EQ(isGuaranteedToTransferExecutionToSuccessor(&I),
               ExpectedAnswers[Index])
         << "Incorrect answer at instruction " << Index << " = " << I;
     Index++;
   }
 }
 
-TEST(ValueTracking, ComputeNumSignBits_PR32045) {
-  StringRef Assembly = "define i32 @f(i32 %a) { "
-                       "  %val = ashr i32 %a, -1 "
-                       "  ret i32 %val "
-                       "} ";
-
-  LLVMContext Context;
-  SMDiagnostic Error;
-  auto M = parseAssemblyString(Assembly, Error, Context);
-  assert(M && "Bad assembly?");
-
-  auto *F = M->getFunction("f");
-  assert(F && "Bad assembly?");
-
-  auto *RVal =
-      cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
-  EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
+TEST_F(ValueTrackingTest, ComputeNumSignBits_PR32045) {
+  parseAssembly(
+      "define i32 @test(i32 %a) {\n"
+      "  %A = ashr i32 %a, -1\n"
+      "  ret i32 %A\n"
+      "}\n");
+  EXPECT_EQ(ComputeNumSignBits(A, M->getDataLayout()), 1u);
 }
 
 // No guarantees for canonical IR in this analysis, so this just bails out. 
-TEST(ValueTracking, ComputeNumSignBits_Shuffle) {
-  StringRef Assembly = "define <2 x i32> @f() { "
-                       "  %val = shufflevector <2 x i32> undef, <2 x i32> undef, <2 x i32> <i32 0, i32 0> "
-                       "  ret <2 x i32> %val "
-                       "} ";
-
-  LLVMContext Context;
-  SMDiagnostic Error;
-  auto M = parseAssemblyString(Assembly, Error, Context);
-  assert(M && "Bad assembly?");
-
-  auto *F = M->getFunction("f");
-  assert(F && "Bad assembly?");
-
-  auto *RVal =
-      cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
-  EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
+TEST_F(ValueTrackingTest, ComputeNumSignBits_Shuffle) {
+  parseAssembly(
+      "define <2 x i32> @test() {\n"
+      "  %A = shufflevector <2 x i32> undef, <2 x i32> undef, <2 x i32> <i32 0, i32 0>\n"
+      "  ret <2 x i32> %A\n"
+      "}\n");
+  EXPECT_EQ(ComputeNumSignBits(A, M->getDataLayout()), 1u);
 }
 
 // No guarantees for canonical IR in this analysis, so a shuffle element that
 // references an undef value means this can't return any extra information. 
-TEST(ValueTracking, ComputeNumSignBits_Shuffle2) {
-  StringRef Assembly = "define <2 x i32> @f(<2 x i1> %x) { "
-                       "  %sext = sext <2 x i1> %x to <2 x i32> "
-                       "  %val = shufflevector <2 x i32> %sext, <2 x i32> undef, <2 x i32> <i32 0, i32 2> "
-                       "  ret <2 x i32> %val "
-                       "} ";
-
-  LLVMContext Context;
-  SMDiagnostic Error;
-  auto M = parseAssemblyString(Assembly, Error, Context);
-  assert(M && "Bad assembly?");
-
-  auto *F = M->getFunction("f");
-  assert(F && "Bad assembly?");
-
-  auto *RVal =
-      cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
-  EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
-}
-
-TEST(ValueTracking, ComputeKnownBits) {
-  StringRef Assembly = "define i32 @f(i32 %a, i32 %b) { "
-                       "  %ash = mul i32 %a, 8 "
-                       "  %aad = add i32 %ash, 7 "
-                       "  %aan = and i32 %aad, 4095 "
-                       "  %bsh = shl i32 %b, 4 "
-                       "  %bad = or i32 %bsh, 6 "
-                       "  %ban = and i32 %bad, 4095 "
-                       "  %mul = mul i32 %aan, %ban "
-                       "  ret i32 %mul "
-                       "} ";
-
-  LLVMContext Context;
-  SMDiagnostic Error;
-  auto M = parseAssemblyString(Assembly, Error, Context);
-  assert(M && "Bad assembly?");
-
-  auto *F = M->getFunction("f");
-  assert(F && "Bad assembly?");
-
-  auto *RVal =
-      cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
-  auto Known = computeKnownBits(RVal, M->getDataLayout());
-  ASSERT_FALSE(Known.hasConflict());
-  EXPECT_EQ(Known.One.getZExtValue(), 10u);
-  EXPECT_EQ(Known.Zero.getZExtValue(), 4278190085u);
+TEST_F(ValueTrackingTest, ComputeNumSignBits_Shuffle2) {
+  parseAssembly(
+      "define <2 x i32> @test(<2 x i1> %x) {\n"
+      "  %sext = sext <2 x i1> %x to <2 x i32>\n"
+      "  %A = shufflevector <2 x i32> %sext, <2 x i32> undef, <2 x i32> <i32 0, i32 2>\n"
+      "  ret <2 x i32> %A\n"
+      "}\n");
+  EXPECT_EQ(ComputeNumSignBits(A, M->getDataLayout()), 1u);
+}
+
+TEST_F(ComputeKnownBitsTest, ComputeKnownBits) {
+  parseAssembly(
+      "define i32 @test(i32 %a, i32 %b) {\n"
+      "  %ash = mul i32 %a, 8\n"
+      "  %aad = add i32 %ash, 7\n"
+      "  %aan = and i32 %aad, 4095\n"
+      "  %bsh = shl i32 %b, 4\n"
+      "  %bad = or i32 %bsh, 6\n"
+      "  %ban = and i32 %bad, 4095\n"
+      "  %A = mul i32 %aan, %ban\n"
+      "  ret i32 %A\n"
+      "}\n");
+  expectKnownBits(/*zero*/ 4278190085u, /*one*/ 10u);
 }
 
-TEST(ValueTracking, ComputeKnownMulBits) {
-  StringRef Assembly = "define i32 @f(i32 %a, i32 %b) { "
-                       "  %aa = shl i32 %a, 5 "
-                       "  %bb = shl i32 %b, 5 "
-                       "  %aaa = or i32 %aa, 24 "
-                       "  %bbb = or i32 %bb, 28 "
-                       "  %mul = mul i32 %aaa, %bbb "
-                       "  ret i32 %mul "
-                       "} ";
-
-  LLVMContext Context;
-  SMDiagnostic Error;
-  auto M = parseAssemblyString(Assembly, Error, Context);
-  assert(M && "Bad assembly?");
-
-  auto *F = M->getFunction("f");
-  assert(F && "Bad assembly?");
-
-  auto *RVal =
-      cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
-  auto Known = computeKnownBits(RVal, M->getDataLayout());
-  ASSERT_FALSE(Known.hasConflict());
-  EXPECT_EQ(Known.One.getZExtValue(), 32u);
-  EXPECT_EQ(Known.Zero.getZExtValue(), 95u);
+TEST_F(ComputeKnownBitsTest, ComputeKnownMulBits) {
+  parseAssembly(
+      "define i32 @test(i32 %a, i32 %b) {\n"
+      "  %aa = shl i32 %a, 5\n"
+      "  %bb = shl i32 %b, 5\n"
+      "  %aaa = or i32 %aa, 24\n"
+      "  %bbb = or i32 %bb, 28\n"
+      "  %A = mul i32 %aaa, %bbb\n"
+      "  ret i32 %A\n"
+      "}\n");
+  expectKnownBits(/*zero*/ 95u, /*one*/ 32u);
 }