Set contract flag when setting unsafe algebra flag

[yuyichao]

Summary

I assume this was a oversight in D31164

[spatel]

This is correct, but I've proposed to remove UnsafeAlgebra in D39304. Do you need this right away, or can we wait for that change to proceed? Another possibility if we need this fixed immediately is to split up my patch so that the 'trans' bit is a follow-up.

[yuyichao]

Do you need this right away, or can we wait for that change to proceed?

Nah, I just notice this by accident when trying to workaround https://bugs.llvm.org/show_bug.cgi?id=35091 I noticed that you fix it too so I will just close this.

include/llvm/IR/Operator.h

SubclassOptionalData =
       (B * FastMathFlags::UnsafeAlgebra);
 
     // Unsafe algebra implies all the others
     if (B) {
       setHasNoNaNs(true);
       setHasNoInfs(true);
       setHasNoSignedZeros(true);
       setHasAllowReciprocal(true);
+      setHasAllowContract(true);
     }
   }
 
   void setHasNoNaNs(bool B) {
     SubclassOptionalData =
       (SubclassOptionalData & ~FastMathFlags::NoNaNs) |
       (B * FastMathFlags::NoNaNs);
   }

unittests/IR/IRBuilderTest.cpp

TEST_F(IRBuilderTest, FastMathFlags) {
   EXPECT_TRUE(Builder.getFastMathFlags().any());
   EXPECT_TRUE(Builder.getFastMathFlags().AllowContract);
   ASSERT_TRUE(isa<Instruction>(FC));
   FAdd = cast<Instruction>(FC);
   EXPECT_TRUE(FAdd->hasAllowContract());
 
   Builder.clearFastMathFlags();
 
+  FC = Builder.CreateFAdd(F, F);
+  EXPECT_FALSE(Builder.getFastMathFlags().any());
+  ASSERT_TRUE(isa<Instruction>(FC));
+  FAdd = cast<Instruction>(FC);
+  EXPECT_FALSE(FAdd->hasNoNaNs());
+  EXPECT_FALSE(FAdd->hasNoInfs());
+  EXPECT_FALSE(FAdd->hasNoSignedZeros());
+  EXPECT_FALSE(FAdd->hasAllowReciprocal());
+  EXPECT_FALSE(FAdd->hasAllowContract());
+  EXPECT_FALSE(FAdd->hasUnsafeAlgebra());
+  FAdd->setHasUnsafeAlgebra(true);
+  EXPECT_TRUE(FAdd->hasNoNaNs());
+  EXPECT_TRUE(FAdd->hasNoInfs());
+  EXPECT_TRUE(FAdd->hasNoSignedZeros());
+  EXPECT_TRUE(FAdd->hasAllowReciprocal());
+  EXPECT_TRUE(FAdd->hasAllowContract());
+  EXPECT_TRUE(FAdd->hasUnsafeAlgebra());
+
   // Test a call with FMF.
   auto CalleeTy = FunctionType::get(Type::getFloatTy(Ctx),
                                     /*isVarArg=*/false);
   auto Callee =
       Function::Create(CalleeTy, Function::ExternalLinkage, "", M.get());
 
   FCall = Builder.CreateCall(Callee, None);
   EXPECT_FALSE(FCall->hasNoNaNs());