Add fneg handling to type analysis (rust-lang#947)

Author: wsmoses

enzyme/Enzyme/TypeAnalysis/TypeAnalysis.cpp

@@ -1151,6 +1151,22 @@ void TypeAnalyzer::visitValue(Value &val) {
   if (!isa<Argument>(&val) && !isa<Instruction>(&val))
     return;
 
+#if LLVM_VERSION_MAJOR >= 10
+  if (auto *FPMO = dyn_cast<FPMathOperator>(&val)) {
+    if (FPMO->getOpcode() == Instruction::FNeg) {
+      Value *op = FPMO->getOperand(0);
+      auto ty = op->getType()->getScalarType();
+      assert(ty->isFloatingPointTy());
+      ConcreteType dt(ty);
+      updateAnalysis(op, TypeTree(ty).Only(-1, nullptr),
+                     cast<Instruction>(&val));
+      updateAnalysis(FPMO, TypeTree(ty).Only(-1, nullptr),
+                     cast<Instruction>(&val));
+      return;
+    }
+  }
+#endif
+
   if (auto inst = dyn_cast<Instruction>(&val)) {
     visit(*inst);
   }

enzyme/test/TypeAnalysis/fneg.ll

@@ -0,0 +1,16 @@
+; RUN: if [ %llvmver -ge 10 ]; then %opt < %s %loadEnzyme -print-type-analysis -type-analysis-func=caller -o /dev/null | FileCheck %s; fi
+
+declare double @f()
+
+define void @caller() {
+entry:
+  %c = call double @f()
+  %n = fneg double %c
+  ret void
+}
+
+; CHECK: caller - {} |
+; CHECK-NEXT: entry
+; CHECK-NEXT:   %c = call double @f(): {[-1]:Float@double}
+; CHECK-NEXT:   %n = fneg double %c: {[-1]:Float@double}
+; CHECK-NEXT:   ret void: {}