[llvm] [mlir] [CMake] Do not set CMP0116 explicitly to old (PR #90385)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 updated https://github.com/llvm/llvm-project/pull/90385

>From c4d53f34c7d9ad96a4d0b7c58971bc4d596565ab Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Sun, 28 Apr 2024 08:34:53 +0000
Subject: [PATCH] [CMake] Do not set CMP0116 explicitly to old

CMP0116 was originally set to old to get rid of warnings. However, this
behavior is now set to new by default with the minimum CMake version that LLVM
requires so does not produce any warnings, and setting it explicitly to old
does produce a warning in newer CMake versions. Due to these reasons, remove
this check for now.

Splitting off from removing the CMP0114 check just in case something breaks.

This also removes two instances of a workaround related to the old
behavior of CMP0116.

Partially fixes #83727.
---
 cmake/Modules/CMakePolicy.cmake   |  6 ------
 llvm/cmake/modules/TableGen.cmake | 15 +++++----------
 mlir/cmake/modules/AddMLIR.cmake  | 13 +++++--------
 3 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/cmake/Modules/CMakePolicy.cmake b/cmake/Modules/CMakePolicy.cmake
index f19dfd71657171..f6ecc40d8f1279 100644
--- a/cmake/Modules/CMakePolicy.cmake
+++ b/cmake/Modules/CMakePolicy.cmake
@@ -1,11 +1,5 @@
 # CMake policy settings shared between LLVM projects
 
-# CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
-# New in CMake 3.20. https://cmake.org/cmake/help/latest/policy/CMP0116.html
-if(POLICY CMP0116)
-  cmake_policy(SET CMP0116 OLD)
-endif()
-
 # MSVC debug information format flags are selected via
 # CMAKE_MSVC_DEBUG_INFORMATION_FORMAT, instead of
 # embedding flags in e.g. CMAKE_CXX_FLAGS_RELEASE.
diff --git a/llvm/cmake/modules/TableGen.cmake b/llvm/cmake/modules/TableGen.cmake
index ffcc718b47775f..d2ff1cfa553b39 100644
--- a/llvm/cmake/modules/TableGen.cmake
+++ b/llvm/cmake/modules/TableGen.cmake
@@ -23,18 +23,13 @@ function(tablegen project ofn)
 
   # Use depfile instead of globbing arbitrary *.td(s) for Ninja.
   if(CMAKE_GENERATOR MATCHES "Ninja")
-    # Make output path relative to build.ninja, assuming located on
-    # ${CMAKE_BINARY_DIR}.
     # CMake emits build targets as relative paths but Ninja doesn't identify
-    # absolute path (in *.d) as relative path (in build.ninja)
-    # Note that tblgen is executed on ${CMAKE_BINARY_DIR} as working directory.
-    file(RELATIVE_PATH ofn_rel
-      ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR}/${ofn})
+    # absolute path (in *.d) as relative path (in build.ninja). Post CMP0116,
+    # CMake handles this discrepancy for us.
     set(additional_cmdline
-      -o ${ofn_rel}
-      -d ${ofn_rel}.d
-      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
-      DEPFILE ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.d
+      -o ${ofn}
+      -d ${ofn}.d
+      DEPFILE ${ofn}.d
       )
     set(local_tds)
     set(global_tds)
diff --git a/mlir/cmake/modules/AddMLIR.cmake b/mlir/cmake/modules/AddMLIR.cmake
index a3324705c525ce..bbe5976d7a3e76 100644
--- a/mlir/cmake/modules/AddMLIR.cmake
+++ b/mlir/cmake/modules/AddMLIR.cmake
@@ -47,15 +47,12 @@ function(_pdll_tablegen project ofn)
     # Make output path relative to build.ninja, assuming located on
     # ${CMAKE_BINARY_DIR}.
     # CMake emits build targets as relative paths but Ninja doesn't identify
-    # absolute path (in *.d) as relative path (in build.ninja)
-    # Note that tblgen is executed on ${CMAKE_BINARY_DIR} as working directory.
-    file(RELATIVE_PATH ofn_rel
-      ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR}/${ofn})
+    # absolute path (in *.d) as relative path (in build.ninja). Post CMP0116,
+    # CMake handles this discrepancy for us.
     set(additional_cmdline
-      -o ${ofn_rel}
-      -d ${ofn_rel}.d
-      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
-      DEPFILE ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.d
+      -o ${ofn}
+      -d ${ofn}.d
+      DEPFILE ${ofn}.d
       )
     set(local_tds)
     set(global_tds)