[PATCH] D142046: [BPF][clang] Ignore stack protector options for BPF target

[Eduard Zingerman via Phabricator via cfe-commits]

eddyz87 created this revision.
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Stack protector builtin functions are not implemented for BPF target,
thus compiling programs with one of the following options would result
in an error:

  -fstack-protector
  -fstack-protector-all
  -fstack-protector-strong

This commit adds logic to ignore these options for BPF target.
Searching through DiagnosticDriverKinds.td shows that all messages for
such kind of behavior are implemented as warnings, this commit follows
the suit.

Here is an example of the diagnostic message:

clang-16: warning: ignoring '-fstack-protector' option \

  as it is not currently supported for target 'bpf' [-Woption-ignored]


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142046

Files:
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/test/CodeGen/bpf-stack-protector.c


Index: clang/test/CodeGen/bpf-stack-protector.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/bpf-stack-protector.c
@@ -0,0 +1,34 @@
+// REQUIRES: bpf-registered-target
+
+// RUN %clang -target bpf -S -emit-llvm -o - %s -fno-stack-protector 2>&1 \
+// RUN        | FileCheck -check-prefix=OFF -check-prefix=COMMON %s
+
+// RUN: %clang -target bpf -S -emit-llvm -o - %s -fstack-protector 2>&1 \
+// RUN:        | FileCheck -check-prefix=ON -check-prefix=COMMON %s
+
+// RUN: %clang -target bpf -S -emit-llvm -o - %s -fstack-protector-all 2>&1 \
+// RUN:        | FileCheck -check-prefix=ALL -check-prefix=COMMON %s
+
+// RUN: %clang -target bpf -S -emit-llvm -o - %s -fstack-protector-strong 2>&1 \
+// RUN:        | FileCheck -check-prefix=STRONG -check-prefix=COMMON %s
+
+typedef __SIZE_TYPE__ size_t;
+
+int printf(const char * _Format, ...);
+size_t strlen(const char *s);
+char *strcpy(char *s1, const char *s2);
+
+//     OFF-NOT: warning
+//          ON: warning: ignoring '-fstack-protector'
+//         ALL: warning: ignoring '-fstack-protector-all'
+//      STRONG: warning: ignoring '-fstack-protector-strong'
+// COMMON-SAME: option as it is not currently supported for target 'bpf'
+
+// COMMON: define {{.*}}void @test1(ptr noundef %msg) #[[A:.*]] {
+void test1(const char *msg) {
+  char a[strlen(msg) + 1];
+  strcpy(a, msg);
+  printf("%s\n", a);
+}
+
+// COMMON-NOT: attributes #[[A]] = {{.*}} ssp
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -3239,6 +3239,12 @@
       StackProtectorLevel = LangOptions::SSPStrong;
     else if (A->getOption().matches(options::OPT_fstack_protector_all))
       StackProtectorLevel = LangOptions::SSPReq;
+
+    if (EffectiveTriple.isBPF() && StackProtectorLevel != LangOptions::SSPOff) {
+      D.Diag(diag::warn_drv_unsupported_option_for_target)
+          << A->getSpelling() << EffectiveTriple.getTriple();
+      StackProtectorLevel = DefaultStackProtectorLevel;
+    }
   } else {
     StackProtectorLevel = DefaultStackProtectorLevel;
   }


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