[FPEnv] [WIP] Verify strictfp attribute correctness

[kpn]

Summary

The strictfp attribute is now defined to require that function definitions be marked strictfp if they contain a strictfp call or a strictfp constrained intrinsic. This patch verifies that all function calls agree with their contained function about the strictfp attribute. It also enforces the attribute if a constrained fp intrinsic is used in a function.

It does _not_ require that all FP instructions in a function be strict if any of this is. That's a later patch.

Note that this patch _cannot_ yet go in the tree because quite a few tests break with this check in place. I'm working on fixing or getting those fixed, and having this patch visible is part of that.

[kpn]

Add strict attribute checks to all function calls.

[arsenm]

Needs tests

[kpn]

Rebase. Add missing tests.

Currently blocked on D70096. Other known/new test failures should be easy to fix.

[arsenm]

llvm/lib/IR/Verifier.cpp

2884

Can check the attribute directly on Call? Also missing tests for this part?

llvm/test/Verifier/fp-intrinsics.ll

94 ↗

(On Diff #233146)

Should have a real call for this, not the constrained intrinsic?

[kbarton]

llvm/lib/IR/Verifier.cpp

358

I don't know how the traversal is done, but is this something that could be done inside visitFunction instead?
That would require all of the instructions have been traversed at that point, and all the intrinsics have been visited, and I'm not sure whether that happens before or ofter visitFunction is called.

[kpn]

llvm/lib/IR/Verifier.cpp

358

Yes, this can be done.

2884

So I can. Thanks for the nudge. And I checked that this is indeed tested.

llvm/test/Verifier/fp-intrinsics.ll

94 ↗

(On Diff #233146)

Well, D70096 will change the "strictfp" to a "nobuiltin" in this case here. I think I'm going to change D70096 so that it leaves strictfp alone on a constrained intrinsic. That way it will fail here with this test. But a real function call will get converted to "nobuiltin" and thus we won't be testing here what we need to be testing.

[kpn]

Address review comments.

[kpn]

Rebase.

We're still not ready to push this, but it can be used to find issues in clang. Once all tests pass with this change we can push it. We're not there yet.

[arsenm]

llvm/lib/IR/Verifier.cpp

2886

I think these Asserts were renamed to Check

2887

Shouldn't require the callsite attributes to match if the underlying declaration is strictfp, your test doesn't cover that case

llvm/test/Verifier/fp-intrinsics.ll

2–9 ↗

(On Diff #345190)

I don't understand the sed usage of this test. Verifier checks can all coexist in the same module. This test only needs a single run line with no sed

llvm/lib/IR/Verifier.cpp

class Verifier : public InstVisitor<Verifier>, VerifierSupport {
 
   /// The result type for a landingpad.
   Type *LandingPadResultTy;
 
   /// Whether we've seen a call to @llvm.localescape in this function
   /// already.
   bool SawFrameEscape;
 
+  /// Whether or not we've seen constrained floating-point intrinsics
+  /// in a function.
+  bool HasConstrainedFP;
+
   /// Whether the current function has a DISubprogram attached to it.
   bool HasDebugInfo = false;
 
   /// Whether source was present on the first DIFile encountered in each CU.
   DenseMap<const DICompileUnit *, bool> HasSourceDebugInfo;
 
   /// Stores the count of how many objects were passed to llvm.localescape for a
   /// given function and the largest index passed to llvm.localrecover.
for (const BasicBlock &BB : F) {
             << "' does not have terminator!\n";
         BB.printAsOperand(*OS, true, MST);
         *OS << "\n";
       }
       return false;
     }
 
     Broken = false;
+    HasConstrainedFP = false;
     // FIXME: We strip const here because the inst visitor strips const.
     visit(const_cast<Function &>(F));
     verifySiblingFuncletUnwinds();
+    verifyFunctionConstrainedFP(F);
     InstsInThisBlock.clear();
     DebugFnArgs.clear();
     LandingPadResultTy = nullptr;
     SawFrameEscape = false;
     SiblingFuncletInfo.clear();
 
     return !Broken;
   }
#include "llvm/IR/Metadata.def"
   void visitResumeInst(ResumeInst &RI);
   void visitCatchPadInst(CatchPadInst &CPI);
   void visitCatchReturnInst(CatchReturnInst &CatchReturn);
   void visitCleanupPadInst(CleanupPadInst &CPI);
   void visitFuncletPadInst(FuncletPadInst &FPI);
   void visitCatchSwitchInst(CatchSwitchInst &CatchSwitch);
   void visitCleanupReturnInst(CleanupReturnInst &CRI);
 
+  void verifyFunctionConstrainedFP(const Function &F);
   void verifySwiftErrorCall(CallBase &Call, const Value *SwiftErrorVal);
   void verifySwiftErrorValue(const Value *SwiftErrorVal);
   void verifyMustTailCall(CallInst &CI);
   bool performTypeCheck(Intrinsic::ID ID, Function *F, Type *Ty, int VT,
                         unsigned ArgNo, std::string &Suffix);
   bool verifyAttributeCount(AttributeList Attrs, unsigned Params);
   void verifyAttributeTypes(AttributeSet Attrs, bool IsFunction,
                             const Value *V);
for (auto &I : BB) {
       if (auto MD = I.getMetadata(LLVMContext::MD_loop))
         for (unsigned i = 1; i < MD->getNumOperands(); ++i)
           VisitDebugLoc(I, dyn_cast_or_null<MDNode>(MD->getOperand(i)));
       if (BrokenDebugInfo)
         return;
     }
 }
 
+
+void Verifier::verifyFunctionConstrainedFP(const Function &F) {
+  if (HasConstrainedFP) {
+    AttributeList Attrs = F.getAttributes();
+    AttributeSet FnAttrs = Attrs.getFnAttributes();
+    Assert (FnAttrs.hasAttribute(Attribute::StrictFP),
+            "Constrained floating point requires function attribute strictfp!",
+            &F);
+  }
+}
+
 // verifyBasicBlock - Verify that a basic block is well formed...
 //
 void Verifier::visitBasicBlock(BasicBlock &BB) {
   InstsInThisBlock.clear();
 
   // Ensure that basic blocks have terminators!
   Assert(BB.getTerminator(), "Basic Block does not have terminator!", &BB);
 
if (Attrs.hasAttribute(AttributeList::FunctionIndex, Attribute::Speculatable)) {
     // declaration is also speculatable.
     Assert(Callee && Callee->isSpeculatable(),
            "speculatable attribute may not apply to call sites", Call);
   }
 
   // Verify call attributes.
   verifyFunctionAttrs(FTy, Attrs, &Call, IsIntrinsic);
 
+  // Verify strictfp attributes match.
+  Function *ContainingF = Call.getFunction();
+  AttributeSet CFnAttrs = ContainingF->getAttributes().getFnAttributes();
+  AttributeSet CallAttrs = Attrs.getFnAttributes();
+  Assert (CFnAttrs.hasAttribute(Attribute::StrictFP) ==
+          CallAttrs.hasAttribute(Attribute::StrictFP),
+            "Functions and their contained calls must match "
+            "in use of attribute strictfp!",
+            ContainingF, &Call);
+
   // Conservatively check the inalloca argument.
   // We have a bug if we can find that there is an underlying alloca without
   // inalloca.
   if (Call.hasInAllocaArgument()) {
     Value *InAllocaArg = Call.getArgOperand(FTy->getNumParams() - 1);
     if (auto AI = dyn_cast<AllocaInst>(InAllocaArg->stripInBoundsOffsets()))
       Assert(AI->isUsedWithInAlloca(),
              "inalloca argument for call has mismatched alloca", AI, Call);
static DISubprogram *getSubprogram(Metadata *LocalScope) {
   assert(!isa<DILocalScope>(LocalScope) && "Unknown type of local scope");
   return nullptr;
 }
 
 void Verifier::visitConstrainedFPIntrinsic(ConstrainedFPIntrinsic &FPI) {
   unsigned NumOperands = FPI.getNumArgOperands();
   bool HasExceptionMD = false;
   bool HasRoundingMD = false;
+  HasConstrainedFP = true;
   switch (FPI.getIntrinsicID()) {
   case Intrinsic::experimental_constrained_sqrt:
   case Intrinsic::experimental_constrained_sin:
   case Intrinsic::experimental_constrained_cos:
   case Intrinsic::experimental_constrained_exp:
   case Intrinsic::experimental_constrained_exp2:
   case Intrinsic::experimental_constrained_log:
   case Intrinsic::experimental_constrained_log10: