[Flang][Driver] Predefine pic/pie macros based on configured level (#153449)

Predefine the `__pic__/__pie__/__PIC__/__PIE__` macros based on the
configured relocation level. This logic mirrors that of the clang
driver, where `__pic__/__PIC__` are defined for both PIC and PIE modes,
but `__pie__/__PIE__` are only defined for PIE mode.

Fixes https://github.com/llvm/llvm-project/issues/135275

1 files changed, 14 insertions, 0 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 708fb7f..3811a87 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -1703,6 +1703,20 @@ void CompilerInvocation::setDefaultPredefinitions() {
   fortranOptions.predefinitions.emplace_back("__flang_patchlevel__",
                                              FLANG_VERSION_PATCHLEVEL_STRING);
 
+  // Add predefinitions based on the relocation model
+  if (unsigned PICLevel = getCodeGenOpts().PICLevel) {
+    fortranOptions.predefinitions.emplace_back("__PIC__",
+                                               std::to_string(PICLevel));
+    fortranOptions.predefinitions.emplace_back("__pic__",
+                                               std::to_string(PICLevel));
+    if (getCodeGenOpts().IsPIE) {
+      fortranOptions.predefinitions.emplace_back("__PIE__",
+                                                 std::to_string(PICLevel));
+      fortranOptions.predefinitions.emplace_back("__pie__",
+                                                 std::to_string(PICLevel));
+    }
+  }
+
   // Add predefinitions based on extensions enabled
   if (frontendOptions.features.IsEnabled(
           Fortran::common::LanguageFeature::OpenACC)) {