[flang] Support -funsafe-cray-pointers

[eugeneepshteyn]

If -funsafe-cray-pointers is passed to flang driver, pass -mmlir -funsafe-cray-pointers to the compiler. This should make it easier to work with the code that relies on behavior before #170908

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[llvmbot]

@llvm/pr-subscribers-flang-driver

@llvm/pr-subscribers-clang-driver

Author: Eugene Epshteyn (eugeneepshteyn)

Changes

If -funsafe-cray-pointers is passed to flang driver, pass '-mmlir -funsafe-cray-pointers' to the compiler.

---

Full diff: https://github.com/llvm/llvm-project/pull/172252.diff

3 Files Affected:

• (modified) clang/include/clang/Options/Options.td (+4)
• (modified) clang/lib/Driver/ToolChains/Flang.cpp (+7)
• (added) flang/test/Driver/unsafe-cray-pointers.f90 (+5)

diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index c38bdd06057a2..9c3b284c4967c 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -7457,6 +7457,10 @@ By default, the heap is used. Allocations of polymorphic types
 are always done on the heap, though this may change in future releases.
   }]>;
 
+defm unsafe_cray_pointers : BoolOptionWithoutMarshalling<"f", "unsafe-cray-pointers",
+  PosFlag<SetTrue, [], [FlangOption, FC1Option], "Optimizations allow for unsafe Cray pointer usages">,
+  NegFlag<SetFalse, [], [FlangOption, FC1Option], "Optimizations don't allow for unsafe Cray pointer usages (default)">>;
+
 def fhermetic_module_files : Flag<["-"], "fhermetic-module-files">, Group<f_Group>,
   HelpText<"Emit hermetic module files (no nested USE association)">;
 
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 2f5e93d139858..4e7ab2cf6edc3 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -201,6 +201,13 @@ void Flang::addCodegenOptions(const ArgList &Args,
       !stackArrays->getOption().matches(options::OPT_fno_stack_arrays))
     CmdArgs.push_back("-fstack-arrays");
 
+  if (Args.hasFlag(options::OPT_funsafe_cray_pointers,
+                   options::OPT_fno_unsafe_cray_pointers, false)) {
+    // TODO: currently passed as MLIR option
+    CmdArgs.push_back("-mmlir");
+    CmdArgs.push_back("-funsafe-cray-pointers");
+  }
+
   Args.addOptInFlag(CmdArgs, options::OPT_fexperimental_loop_fusion,
                     options::OPT_fno_experimental_loop_fusion);
 
diff --git a/flang/test/Driver/unsafe-cray-pointers.f90 b/flang/test/Driver/unsafe-cray-pointers.f90
new file mode 100644
index 0000000000000..bd8cafc1602f3
--- /dev/null
+++ b/flang/test/Driver/unsafe-cray-pointers.f90
@@ -0,0 +1,5 @@
+! RUN: %flang -funsafe-cray-pointers -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-ON
+! RUN: %flang -fno-unsafe-cray-pointers -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-OFF
+
+! CHECK-ON: "-mmlir" "-funsafe-cray-pointers"
+! CHECK-OFF-NOT: "-mmlir" "-funsafe-cray-pointers"

[vzakhari]

LGTM