[clang] [llvm] [IR] Add getelementptr nusw and nuw flags (PR #90824)

[via cfe-commits]

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@@ -0,0 +1,93 @@
+//===-- llvm/GEPNoWrapFlags.h - NoWrap flags for GEPs -----------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the nowrap flags for getelementptr operators.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_GEPNOWRAPFLAGS_H
+#define LLVM_IR_GEPNOWRAPFLAGS_H
+
+namespace llvm {
+
+/// Represents flags for the getelementptr instruction/expression.
+/// The following flags are supported:
+///  * inbounds (implies nusw)
+///  * nusw (no unsigned signed wrap)
+///  * nuw (no unsigned wrap)
+/// See LangRef for a description of their semantics.
+class GEPNoWrapFlags {
+  enum : unsigned {
+    InBoundsFlag = (1 << 0),
+    NUSWFlag = (1 << 1),
+    NUWFlag = (1 << 2),
+  };
+
+  unsigned Flags;
+  GEPNoWrapFlags(unsigned Flags) : Flags(Flags) {
+    assert((!isInBounds() || hasNoUnsignedSignedWrap()) &&
+           "inbounds implies nusw");
+  }
+
+public:
+  GEPNoWrapFlags() : Flags(0) {}
+  // For historical reasons, interpret plain boolean as InBounds.
+  // TODO: Migrate users to pass explicit GEPNoWrapFlags and remove this ctor.
+  GEPNoWrapFlags(bool IsInBounds)
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goldsteinn wrote:

Why do we need this CTOR? Seems to be entirely encapsulated with `inBounds` which is more expressive. Seems a bit non-intuitive to only have 1 bool constructor for a flags class that represents 3...

https://github.com/llvm/llvm-project/pull/90824