[Driver] Default CLANG_DEFAULT_PIE_ON_LINUX to ON

Default the option introduced in D113372 to ON to match all(?) major Linux
distros. This matches GCC and improves consistency with Android and linux-musl
which always default to PIE.
Note: CLANG_DEFAULT_PIE_ON_LINUX will be removed in the future.

Reviewed By: thesamesam

Differential Revision: https://reviews.llvm.org/D120305

clang/CMakeLists.txt

@@ -245,7 +245,7 @@ set(PPC_LINUX_DEFAULT_IEEELONGDOUBLE OFF CACHE BOOL
 set(CLANG_SPAWN_CC1 OFF CACHE BOOL
     "Whether clang should use a new process for the CC1 invocation")
 
-option(CLANG_DEFAULT_PIE_ON_LINUX "Default to -fPIE and -pie on Linux" OFF)
+option(CLANG_DEFAULT_PIE_ON_LINUX "Default to -fPIE and -pie on linux-gnu" ON)
 
 # TODO: verify the values against LangStandards.def?
 set(CLANG_DEFAULT_STD_C "" CACHE STRING

clang/docs/ReleaseNotes.rst

@@ -183,6 +183,12 @@ Internal API Changes
 Build System Changes
 --------------------
 
+* CMake ``-DCLANG_DEFAULT_PIE_ON_LINUX=ON`` is now the default. This is used by
+  linux-gnu systems to decide whether ``-fPIE -pie`` is the default (instead of
+  ``-fno-pic -no-pie``). This matches GCC installations on many Linux distros.
+  Note: linux-android and linux-musl always default to ``-fPIE -pie``, ignoring
+  this variable. ``-DCLANG_DEFAULT_PIE_ON_LINUX`` will be removed in the future.
+
 AST Matchers
 ------------
 

clang/test/Driver/hip-fpie-option.hip

-// REQUIRES: clang-driver, amdgpu-registered-target
+// REQUIRES: clang-driver, amdgpu-registered-target, default-pie-on-linux
 
 // -fPIC and -fPIE only affects host relocation model.
 // device compilation always uses PIC. 
 
 // RUN: %clang -### -target x86_64-unknown-linux-gnu \
 // RUN:   --offload-arch=gfx906 %s -nogpulib -nogpuinc \
-// RUN:   2>&1 | FileCheck -check-prefixes=DEV,HOST-STATIC %s
+// RUN:   2>&1 | FileCheck -check-prefixes=DEV,HOST-PIE %s
 
 // RUN: %clang -### -target x86_64-unknown-linux-gnu \
 // RUN:   -fgpu-rdc --offload-arch=gfx906 %s -nogpulib -nogpuinc \
-// RUN:   2>&1 | FileCheck -check-prefixes=DEV,HOST-STATIC %s
+// RUN:   2>&1 | FileCheck -check-prefixes=DEV,HOST-PIE %s
 
 // RUN: %clang -### -target x86_64-unknown-linux-gnu \
 // RUN:   --offload-arch=gfx906 %s -nogpulib -nogpuinc \
@@ -32,7 +32,6 @@
 // RUN:   2>&1 | FileCheck -check-prefixes=DEV,HOST-PIE %s
 
 // DEV-DAG: {{".*clang.*".* "-triple" "amdgcn-amd-amdhsa".* "-mrelocation-model" "pic" "-pic-level" "[1|2]".* "-mframe-pointer=all"}}
-// HOST-STATIC-DAG: {{".*clang.*".* "-triple" "x86_64-unknown-linux-gnu".* "-mrelocation-model" "static"}}
 // HOST-PIC-DAG: {{".*clang.*".* "-triple" "x86_64-unknown-linux-gnu".* "-mrelocation-model" "pic" "-pic-level" "2"}}
 // HOST-PIC-NOT: "-pic-is-pie"
 // HOST-PIE-DAG: {{".*clang.*".* "-triple" "x86_64-unknown-linux-gnu".* "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie"}}

llvm/utils/gn/secondary/clang/include/clang/Config/BUILD.gn

@@ -9,7 +9,7 @@ write_cmake_config("Config") {
   output = "$target_gen_dir/config.h"
   values = [
     "BUG_REPORT_URL=https://github.com/llvm/llvm-project/issues/",
-    "CLANG_DEFAULT_PIE_ON_LINUX=",
+    "CLANG_DEFAULT_PIE_ON_LINUX=1",
     "CLANG_DEFAULT_LINKER=",
     "CLANG_DEFAULT_STD_C=",
     "CLANG_DEFAULT_STD_CXX=",

utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h

@@ -23,7 +23,7 @@
 #define BUG_REPORT_URL "https://github.com/llvm/llvm-project/issues/"
 
 /* Default to -fPIE and -pie on Linux. */
-#define CLANG_DEFAULT_PIE_ON_LINUX 0
+#define CLANG_DEFAULT_PIE_ON_LINUX 1
 
 /* Default linker to use. */
 #define CLANG_DEFAULT_LINKER ""