[llvm] r314312 - [Support] mapped_file_region: store size as size_t

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Wed Sep 27 08:59:16 2017
New Revision: 314312

URL: http://llvm.org/viewvc/llvm-project?rev=314312&view=rev
Log:
[Support] mapped_file_region: store size as size_t

Summary:
Found when testing stage-2 build with D38101.

```
In file included from /build/llvm/lib/Support/Path.cpp:1045:
/build/llvm/lib/Support/Unix/Path.inc:648:14: error: comparison 'uint64_t' (aka 'unsigned long') > 18446744073709551615 is always false [-Werror,-Wtautological-constant-compare]
  if (length > std::numeric_limits<size_t>::max()) {
      ~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

`size_t` is `uint64_t` here, apparently, thus any `uint64_t` value
always fits into `size_t`.

Initial patch was to use some preprocessor logic to
not check if the size is known to fit at compile time.
But Zachary Turner suggested using this approach.

Reviewers: Bigcheese, rafael, zturner, mehdi_amini

Reviewed by (via email): zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38132

Modified:
    llvm/trunk/include/llvm/Support/FileSystem.h
    llvm/trunk/lib/Support/Unix/Path.inc

Modified: llvm/trunk/include/llvm/Support/FileSystem.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/FileSystem.h?rev=314312&r1=314311&r2=314312&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/FileSystem.h (original)
+++ llvm/trunk/include/llvm/Support/FileSystem.h Wed Sep 27 08:59:16 2017
@@ -745,7 +745,7 @@ public:
 
 private:
   /// Platform-specific mapping state.
-  uint64_t Size;
+  size_t Size;
   void *Mapping;
 
   std::error_code init(int FD, uint64_t Offset, mapmode Mode);
@@ -758,12 +758,12 @@ public:
   /// \param fd An open file descriptor to map. mapped_file_region takes
   ///   ownership if closefd is true. It must have been opended in the correct
   ///   mode.
-  mapped_file_region(int fd, mapmode mode, uint64_t length, uint64_t offset,
+  mapped_file_region(int fd, mapmode mode, size_t length, uint64_t offset,
                      std::error_code &ec);
 
   ~mapped_file_region();
 
-  uint64_t size() const;
+  size_t size() const;
   char *data() const;
 
   /// Get a const view of the data. Modifying this memory has undefined

Modified: llvm/trunk/lib/Support/Unix/Path.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/Path.inc?rev=314312&r1=314311&r2=314312&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Unix/Path.inc (original)
+++ llvm/trunk/lib/Support/Unix/Path.inc Wed Sep 27 08:59:16 2017
@@ -641,15 +641,9 @@ std::error_code mapped_file_region::init
   return std::error_code();
 }
 
-mapped_file_region::mapped_file_region(int fd, mapmode mode, uint64_t length,
+mapped_file_region::mapped_file_region(int fd, mapmode mode, size_t length,
                                        uint64_t offset, std::error_code &ec)
     : Size(length), Mapping() {
-  // Make sure that the requested size fits within SIZE_T.
-  if (length > std::numeric_limits<size_t>::max()) {
-    ec = make_error_code(errc::invalid_argument);
-    return;
-  }
-
   ec = init(fd, offset, mode);
   if (ec)
     Mapping = nullptr;