Set some fast math attributes in setFunctionAttributes

[arsenm]

Summary

This will provide a more consistent view to codegen for these
attributes. The current system is somewhat awkward, and the fields in
TargetOptions are reset based on the command line flag if the
attribute isn't set. By forcing these attributes with the flag, there
can never be an inconsistency in the behavior if code directly
inspects the attribute on the function without considering the command
line flags.

[arsenm]

ping

[arsenm]

ping

[arsenm]

ping

[echristo]

It'd be much nicer to get rid of resetTargetOptions here? Can we do that yet?

[arsenm]

In D71258#1823070, @echristo wrote:

It'd be much nicer to get rid of resetTargetOptions here? Can we do that yet?

I've thought about putting a bit in the function/MachineFunction for these, partly as an aid to writing IR-free MIR tests. I think that's the next step

[echristo]

OK.

[arsenm]

c378e52cb9d1197bd828008ffdeaf3cebdca1506

llvm/include/llvm/CodeGen/CommandFlags.inc

LLVM_ATTRIBUTE_UNUSED static std::vector<std::string> getFeatureList() {
   }
 
   for (unsigned i = 0; i != MAttrs.size(); ++i)
     Features.AddFeature(MAttrs[i]);
 
   return Features.getFeatures();
 }
 
+static void renderBoolStringAttr(AttrBuilder &B, StringRef Name, bool Val) {
+  B.addAttribute(Name, Val ? "true" : "false");
+}
+
+#define HANDLE_BOOL_ATTR(CL, AttrName)                              \
+  do {                                                              \
+    if (CL.getNumOccurrences() > 0 && !F.hasFnAttribute(AttrName))  \
+      renderBoolStringAttr(NewAttrs, AttrName, CL);                 \
+  } while (0)
+
+
 /// Set function attributes of function \p F based on CPU, Features, and command
 /// line flags.
 LLVM_ATTRIBUTE_UNUSED static void
 setFunctionAttributes(StringRef CPU, StringRef Features, Function &F) {
   auto &Ctx = F.getContext();
   AttributeList Attrs = F.getAttributes();
   AttrBuilder NewAttrs;
 
else if (FramePointerUsage == llvm::FramePointer::None)
       NewAttrs.addAttribute("frame-pointer", "none");
   }
   if (DisableTailCalls.getNumOccurrences() > 0)
     NewAttrs.addAttribute("disable-tail-calls",
                           toStringRef(DisableTailCalls));
   if (StackRealign)
     NewAttrs.addAttribute("stackrealign");
 
+  HANDLE_BOOL_ATTR(EnableUnsafeFPMath, "unsafe-fp-math");
+  HANDLE_BOOL_ATTR(EnableNoInfsFPMath, "no-infs-fp-math");
+  HANDLE_BOOL_ATTR(EnableNoNaNsFPMath, "no-nans-fp-math");
+  HANDLE_BOOL_ATTR(EnableNoSignedZerosFPMath, "no-signed-zeros-fp-math");
+
   if (TrapFuncName.getNumOccurrences() > 0)
     for (auto &B : F)
       for (auto &I : B)
         if (auto *Call = dyn_cast<CallInst>(&I))
           if (const auto *F = Call->getCalledFunction())
             if (F->getIntrinsicID() == Intrinsic::debugtrap ||
                 F->getIntrinsicID() == Intrinsic::trap)
               Call->addAttribute(

llvm/lib/Target/TargetMachine.cpp

 
 TargetMachine::~TargetMachine() = default;
 
 bool TargetMachine::isPositionIndependent() const {
   return getRelocationModel() == Reloc::PIC_;
 }
 
 /// Reset the target options based on the function's attributes.
+/// setFunctionAttributes should have made the raw attribute value consistent
+/// with the command line flag if used.
+//
 // FIXME: This function needs to go away for a number of reasons:
 // a) global state on the TargetMachine is terrible in general,
 // b) these target options should be passed only on the function
 //    and not on the TargetMachine (via TargetOptions) at all.
 void TargetMachine::resetTargetOptions(const Function &F) const {
-#define RESET_OPTION(X, Y)                                                     \
-  do {                                                                         \
-    if (F.hasFnAttribute(Y))                                                   \
-      Options.X = (F.getFnAttribute(Y).getValueAsString() == "true");          \
-    else                                                                       \
-      Options.X = DefaultOptions.X;                                            \
+#define RESET_OPTION(X, Y)                                              \
+  do {                                                                  \
+    Options.X = (F.getFnAttribute(Y).getValueAsString() == "true");     \
   } while (0)
 
   RESET_OPTION(UnsafeFPMath, "unsafe-fp-math");
   RESET_OPTION(NoInfsFPMath, "no-infs-fp-math");
   RESET_OPTION(NoNaNsFPMath, "no-nans-fp-math");
   RESET_OPTION(NoSignedZerosFPMath, "no-signed-zeros-fp-math");
 }