[FuzzMutate] Correct type cast and add unit test for FCmp

[oakrc]

Summary

This revision fixes an incorrect type cast from Instruction to ICmpInstr, which should have been to FCmpInstr instead. It turns out that StrategiesTest.cpp was missing a test case for InstModificationIRStrategy and FCmp, which is also now implemented in this revision. After this revision, llvm-stress in D148854 no longer crashes randomly.

[MaskRay]

The commit does not list the original author as the author.

If a patch is not uploaded with arc diff 'HEAD^', arc patch D148972 does not have the author information. You'll need to fix it with git commit --amend --author=

[Peter]

In D148972#4289158, @MaskRay wrote:

The commit does not list the original author as the author.

If a patch is not uploaded with arc diff 'HEAD^', arc patch D148972 does not have the author information. You'll need to fix it with git commit --amend --author=

Thanks, it's my first time to commit for someone, I am working on it. It's already pushed to main, so can I revert that change and push a new commit again?

[Peter]

In D148972#4289158, @MaskRay wrote:

The commit does not list the original author as the author.

If a patch is not uploaded with arc diff 'HEAD^', arc patch D148972 does not have the author information. You'll need to fix it with git commit --amend --author=

Done.

llvm/lib/FuzzMutate/IRMutator.cpp

void InstModificationIRStrategy::mutate(Instruction &Inst,
   case Instruction::UDiv:
   case Instruction::SDiv:
   case Instruction::LShr:
   case Instruction::AShr:
     Modifications.push_back([&Inst] { Inst.setIsExact(!Inst.isExact()); });
     break;
 
   case Instruction::FCmp:
-    CI = cast<ICmpInst>(&Inst);
+    CI = cast<FCmpInst>(&Inst);
     for (unsigned p = CmpInst::FIRST_FCMP_PREDICATE;
          p <= CmpInst::LAST_FCMP_PREDICATE; p++) {
       Modifications.push_back(
           [CI, p]() { CI->setPredicate(static_cast<CmpInst::Predicate>(p)); });
     }
     break;
   }
 

llvm/unittests/FuzzMutate/StrategiesTest.cpp

for (int i = 0; i < 100; ++i) {
     Mutator->mutateModule(*M, Seed + i, Source.size(), Source.size() + 100);
     EXPECT_TRUE(!verifyModule(*M, &errs()));
     FoundNE |= CI->getPredicate() == CmpInst::ICMP_NE;
   }
 
   EXPECT_TRUE(FoundNE);
 }
 
+TEST(InstModificationIRStrategyTest, FCmp) {
+  LLVMContext Ctx;
+  StringRef Source = "\n\
+      define i1 @test(float %x) {\n\
+        %a = fcmp oeq float %x, 10.0\n\
+        ret i1 %a\n\
+      }";
+
+  auto Mutator = createMutator<InstModificationIRStrategy>();
+  ASSERT_TRUE(Mutator);
+
+  auto M = parseAssembly(Source.data(), Ctx);
+  auto &F = *M->begin();
+  CmpInst *CI = cast<CmpInst>(&*F.begin()->begin());
+  ASSERT_TRUE(M && !verifyModule(*M, &errs()));
+  bool FoundONE = false;
+  for (int i = 0; i < 100; ++i) {
+    Mutator->mutateModule(*M, Seed + i, Source.size(), Source.size() + 100);
+    EXPECT_TRUE(!verifyModule(*M, &errs()));
+    FoundONE |= CI->getPredicate() == CmpInst::FCMP_ONE;
+  }
+
+  EXPECT_TRUE(FoundONE);
+}
+
 TEST(InstModificationIRStrategyTest, GEP) {
   LLVMContext Ctx;
   StringRef Source = "\n\
       define i32* @test(i32* %ptr) {\n\
         %gep = getelementptr i32, i32* %ptr, i32 10\n\
         ret i32* %gep\n\
       }";