[llvm] add GenericFloatingPointPredicateUtils (#140254)

add `GenericFloatingPointPredicateUtils` in order to generalize
effects of floating point comparisons on `KnownFPClass` for both IR and
MIR.

---------

Co-authored-by: Matt Arsenault <arsenm2@gmail.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineFloatingPointPredicateUtils.cpp b/llvm/lib/CodeGen/MachineFloatingPointPredicateUtils.cpp
new file mode 100644
index 0000000..3f640de
--- /dev/null
+++ b/llvm/lib/CodeGen/MachineFloatingPointPredicateUtils.cpp
@@ -0,0 +1,48 @@
+//===- MachineFloatingPointPredicateUtils.cpp -----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineFloatingPointPredicateUtils.h"
+#include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"
+#include "llvm/CodeGen/LowLevelTypeUtils.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineSSAContext.h"
+#include "llvm/IR/Constants.h"
+#include <optional>
+
+namespace llvm {
+
+using namespace MIPatternMatch;
+
+template <>
+DenormalMode
+MachineFloatingPointPredicateUtils::queryDenormalMode(const MachineFunction &MF,
+                                                      Register Val) {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  LLT Ty = MRI.getType(Val).getScalarType();
+  return MF.getDenormalMode(getFltSemanticForLLT(Ty));
+}
+
+template <>
+bool MachineFloatingPointPredicateUtils::lookThroughFAbs(
+    const MachineFunction &MF, Register LHS, Register &Src) {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  return mi_match(LHS, MRI, m_GFabs(m_Reg(Src)));
+}
+
+template <>
+std::optional<APFloat> MachineFloatingPointPredicateUtils::matchConstantFloat(
+    const MachineFunction &MF, Register Val) {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  const ConstantFP *ConstVal;
+  if (mi_match(Val, MRI, m_GFCst(ConstVal)))
+    return ConstVal->getValueAPF();
+
+  return std::nullopt;
+}
+
+} // namespace llvm