[PATCH] D128333: [clang][flang] Disable defaulting to `-fpie` for LLVM Flang

[Andrzej Warzynski via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGb405407a4899: [clang][flang] Disable defaulting to `-fpie` for LLVM Flang (authored by awarzynski).

Changed prior to commit:
  https://reviews.llvm.org/D128333?vs=440874&id=440884#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D128333/new/

https://reviews.llvm.org/D128333

Files:
  clang/lib/Driver/ToolChains/Linux.cpp
  flang/docs/ReleaseNotes.md
  flang/test/Driver/pic-flags.f90


Index: flang/test/Driver/pic-flags.f90
===================================================================
--- /dev/null
+++ flang/test/Driver/pic-flags.f90
@@ -0,0 +1,24 @@
+! Verify that in contrast to Clang, Flang does not default to generating position independent executables/code
+
+!-------------
+! RUN COMMANDS
+!-------------
+! RUN: %flang -### %s --target=aarch64-linux-gnu 2>&1 | FileCheck %s --check-prefix=CHECK-NOPIE
+! RUN: %flang -### %s --target=aarch64-linux-gnu -fno-pie 2>&1 | FileCheck %s --check-prefix=CHECK-NOPIE
+
+! RUN: %flang -### %s --target=aarch64-linux-gnu -fpie 2>&1 | FileCheck %s --check-prefix=CHECK-PIE
+
+!----------------
+! EXPECTED OUTPUT
+!----------------
+! CHECK-NOPIE: "-fc1"
+! CHECk-NOPIE-NOT: "-fpic"
+! CHECK-NOPIE: "{{.*}}ld"
+! CHECK-NOPIE-NOT: "-pie"
+
+! CHECK-PIE: "-fc1"
+!! TODO Once Flang supports `-fpie`, it //should// use -fpic when invoking `flang -fc1`. Update the following line once `-fpie` is
+! available.
+! CHECk-PIE-NOT: "-fpic"
+! CHECK-PIE: "{{.*}}ld"
+! CHECK-PIE-NOT: "-pie"
Index: flang/docs/ReleaseNotes.md
===================================================================
--- flang/docs/ReleaseNotes.md
+++ flang/docs/ReleaseNotes.md
@@ -28,6 +28,13 @@
 
 ## Non-comprehensive list of changes in this release
 * The bash wrapper script, `flang`, is renamed as `flang-to-external-fc`.
+* In contrast to Clang, Flang will not default to using `-fpie` when linking
+  executables. This is only a temporary solution and the goal is to align with
+  Clang in the near future. First, however, the frontend driver needs to be
+  extended so that it can generate position independent code (that requires
+  adding support for e.g. `-fpic` and `-mrelocation-model` in `flang-new
+  -fc1`). Once that is available, support for the `-fpie` can officially be
+  added and the default behaviour updated.
 
 ## New Compiler Flags
 * Refined how `-f{no-}color-diagnostics` is treated to better align with Clang.
Index: clang/lib/Driver/ToolChains/Linux.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Linux.cpp
+++ clang/lib/Driver/ToolChains/Linux.cpp
@@ -699,8 +699,11 @@
 }
 
 bool Linux::isPIEDefault(const llvm::opt::ArgList &Args) const {
-  return CLANG_DEFAULT_PIE_ON_LINUX || getTriple().isAndroid() ||
-         getTriple().isMusl() || getSanitizerArgs(Args).requiresPIE();
+  // TODO: Remove the special treatment for Flang once its frontend driver can
+  // generate position independent code.
+  return !getDriver().IsFlangMode() &&
+         (CLANG_DEFAULT_PIE_ON_LINUX || getTriple().isAndroid() ||
+          getTriple().isMusl() || getSanitizerArgs(Args).requiresPIE());
 }
 
 bool Linux::IsAArch64OutlineAtomicsDefault(const ArgList &Args) const {


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