[Driver] Add options to control workaround for Cortex-A53 Erratum 843419 (#143915)

Implement the -mfix-cortex-a53-843419 and -mno-fix-cortex-a53-843419 options,
which have been introduced to GCC to allow the user to control the workaround
for the erratum. If the option is enabled (which is the default, unchanged by
this patch), Clang passes --fix-cortex-a53-843419 to the linker when it cannot
ensure that the target is not a Cortex A53, otherwise it doesn't.

See https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html#index-mfix-cortex-a53-843419
for information on the GCC options.

Author: bryanpkc

clang/include/clang/Driver/Options.td

@@ -5150,10 +5150,16 @@ def mno_fix_cortex_a72_aes_1655431 : Flag<["-"], "mno-fix-cortex-a72-aes-1655431
   Alias<mno_fix_cortex_a57_aes_1742098>;
 def mfix_cortex_a53_835769 : Flag<["-"], "mfix-cortex-a53-835769">,
   Group<m_aarch64_Features_Group>,
-  HelpText<"Workaround Cortex-A53 erratum 835769 (AArch64 only)">;
+  HelpText<"Work around Cortex-A53 erratum 835769 (AArch64 only)">;
 def mno_fix_cortex_a53_835769 : Flag<["-"], "mno-fix-cortex-a53-835769">,
   Group<m_aarch64_Features_Group>,
-  HelpText<"Don't workaround Cortex-A53 erratum 835769 (AArch64 only)">;
+  HelpText<"Don't work around Cortex-A53 erratum 835769 (AArch64 only)">;
+def mfix_cortex_a53_843419 : Flag<["-"], "mfix-cortex-a53-843419">,
+  Group<m_aarch64_Features_Group>,
+  HelpText<"Work around Cortex-A53 erratum 843419 (AArch64 only)">;
+def mno_fix_cortex_a53_843419 : Flag<["-"], "mno-fix-cortex-a53-843419">,
+  Group<m_aarch64_Features_Group>,
+  HelpText<"Don't work around Cortex-A53 erratum 843419 (AArch64 only)">;
 def mmark_bti_property : Flag<["-"], "mmark-bti-property">,
   Group<m_aarch64_Features_Group>,
   HelpText<"Add .note.gnu.property with BTI to assembly files (AArch64 only)">;

clang/lib/Driver/ToolChains/Fuchsia.cpp

@@ -91,7 +91,9 @@ void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("--execute-only");
 
     std::string CPU = getCPUName(D, Args, Triple);
-    if (CPU.empty() || CPU == "generic" || CPU == "cortex-a53")
+    if (Args.hasFlag(options::OPT_mfix_cortex_a53_843419,
+                     options::OPT_mno_fix_cortex_a53_843419, true) &&
+        (CPU.empty() || CPU == "generic" || CPU == "cortex-a53"))
       CmdArgs.push_back("--fix-cortex-a53-843419");
   }
 

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -402,7 +402,9 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   // Most Android ARM64 targets should enable the linker fix for erratum
   // 843419. Only non-Cortex-A53 devices are allowed to skip this flag.
-  if (Arch == llvm::Triple::aarch64 && (isAndroid || isOHOSFamily)) {
+  if (Arch == llvm::Triple::aarch64 && (isAndroid || isOHOSFamily) &&
+      Args.hasFlag(options::OPT_mfix_cortex_a53_843419,
+                   options::OPT_mno_fix_cortex_a53_843419, true)) {
     std::string CPU = getCPUName(D, Args, Triple);
     if (CPU.empty() || CPU == "generic" || CPU == "cortex-a53")
       CmdArgs.push_back("--fix-cortex-a53-843419");

clang/test/Driver/android-link.cpp

@@ -16,6 +16,16 @@
 // RUN: FileCheck -check-prefix=CORTEX-A57 < %t %s
 
 // RUN: %clang --target=aarch64-none-linux-android \
+// RUN:   -mno-fix-cortex-a53-843419 \
+// RUN:   -### -v %s 2> %t
+// RUN: FileCheck -check-prefix=OVERRIDDEN < %t %s
+//
+// RUN: %clang -target aarch64-none-linux-android \
+// RUN:   -mno-fix-cortex-a53-843419 -mfix-cortex-a53-843419 \
+// RUN:   -### -v %s 2> %t
+// RUN: FileCheck -check-prefix=OVERRIDDEN2 < %t %s
+//
+// RUN: %clang -target aarch64-none-linux-android \
 // RUN:   -### -v %s 2> %t
 // RUN: FileCheck -check-prefix=MAX-PAGE-SIZE-16KB < %t %s
 
@@ -31,6 +41,8 @@
 // GENERIC-ARM: --fix-cortex-a53-843419
 // CORTEX-A53: --fix-cortex-a53-843419
 // CORTEX-A57-NOT: --fix-cortex-a53-843419
+// OVERRIDDEN-NOT: --fix-cortex-a53-843419
+// OVERRIDDEN2: --fix-cortex-a53-843419
 // MAX-PAGE-SIZE-4KB: "-z" "max-page-size=4096"
 // MAX-PAGE-SIZE-16KB: "-z" "max-page-size=16384"
 // NO-MAX-PAGE-SIZE-16KB-NOT: "-z" "max-page-size=16384"