[PATCH] D121983: Driver: Don't warn on -mbranch-protection when linking

[Tom Stellard via Phabricator via cfe-commits]

tstellar created this revision.
tstellar added reviewers: chill, vhscampos, stuij, amilendra.
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tstellar requested review of this revision.
Herald added a project: clang.

The -mbranch-protection definition in Options.td was not given a Group,
so this was causing clang to emit a -Wunused-command-line-argument
warning when this flag was passed to the linker driver.  This was a
problem, because some build systems, like cmake, automatically pass the
C flags to the linker.  Therefore, any program that was compiled with
-Werror and -mbranch-protection would fail to link with the error:

argument unused during compilation: '-mbranch-protection=standard' [-Werror,-Wunused-command-line-argument]


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D121983

Files:
  clang/include/clang/Driver/Options.td
  clang/test/Driver/Inputs/main.c
  clang/test/Driver/aarch64-security-options.c


Index: clang/test/Driver/aarch64-security-options.c
===================================================================
--- clang/test/Driver/aarch64-security-options.c
+++ clang/test/Driver/aarch64-security-options.c
@@ -27,6 +27,10 @@
 // RUN: %clang -target aarch64--none-eabi -c %s -### -mbranch-protection=bar     2>&1 | \
 // RUN: FileCheck %s --check-prefix=BAD-BP-PROTECTION --check-prefix=WARN
 
+// RUN: %clang -target aarch64--none-eabi -o %t-main.o -mbranch-protection=standard -c %S/Inputs/main.c
+// RUN: %clang -target aarch64--none-eabi -o %t-main -mbranch-protection=standard %t-main.o 2>&1 | \
+// RUN: FileCheck --allow-empty %s --check-prefix=LINKER-DRIVER
+
 // WARN-NOT: warning: ignoring '-mbranch-protection=' option because the 'aarch64' architecture does not support it [-Wbranch-protection]
 
 // RA-OFF: "-msign-return-address=none"
@@ -46,3 +50,7 @@
 
 // BAD-B-KEY-COMBINATION: invalid branch protection option 'b-key' in '-mbranch-protection={{.*}}'
 // BAD-LEAF-COMBINATION: invalid branch protection option 'leaf' in '-mbranch-protection={{.*}}'
+
+// Check that the linker driver doesn't warn about -mbranch-protection=standard
+// as an unused option.
+// LINKER-DRIVER-NOT: warning:
Index: clang/test/Driver/Inputs/main.c
===================================================================
--- /dev/null
+++ clang/test/Driver/Inputs/main.c
@@ -0,0 +1,3 @@
+int main(int argc, char **argv) {
+  return 0;
+}
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -3442,6 +3442,7 @@
   Flags<[CC1Option]>, Group<m_Group>, Values<"none,all,non-leaf">,
   HelpText<"Select return address signing scope">;
 def mbranch_protection_EQ : Joined<["-"], "mbranch-protection=">,
+  Group<m_Group>,
   HelpText<"Enforce targets of indirect branches and function returns">;
 
 def mharden_sls_EQ : Joined<["-"], "mharden-sls=">,


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