This patch enables errors when external calls are created.

When architectural limitations or usage of builtins implies the compiler
to create function calls to external libraries that implement the
functionality, GCC will now report an error claiming that this function
calls are not compatible with eBPF target.
Examples of those are the usage of __builtin_memmove and a sign division
in BPF ISA v3 or below that will require to call __divdi3.
This is currently an eBPF limitation which does not support linking of
object files but rather "raw" non linked ones. Those object files are
loaded and relocated by libbpf and the kernel.

gcc/ChangeLog:
	* config/bpf/bpf.cc (bpf_output_call): Report error in case the
	function call is for a builtin.
	(bpf_external_libcall): Added target hook to detect and report
	error when other external calls that are not builtins.

gcc/testsuite/ChangeLog:
	* gcc.target/bpf/atomic-cmpxchg-2.c: Adapted.
	* gcc.target/bpf/atomic-fetch-op-3.c: Adapted.
	* gcc.target/bpf/atomic-op-3.c: Adapted.
	* gcc.target/bpf/atomic-xchg-2.c: Adapted.
	* gcc.target/bpf/diag-sdiv.c: Adapted.
	* gcc.target/bpf/diag-smod.c: Adapted.

diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
index 4bfba289546cac9b208e37ea32337ac4a55382d9..80108018c24fde1ee3cec5209364359cb4855616 100644 (file)
--- a/gcc/config/bpf/bpf.cc
+++ b/gcc/config/bpf/bpf.cc
@@ -746,6 +746,15 @@ bpf_output_call (rtx target)
            xops[0] = GEN_INT (TREE_INT_CST_LOW (TREE_VALUE (attr_args)));
            output_asm_insn ("call\t%0", xops);
          }
+       else if (fndecl_built_in_p (decl))
+         {
+           /* For now lets report this as an error while we are not able to
+              link eBPF object files.  In particular with libgcc.  */
+           tree name = DECL_NAME (decl);
+           error ("call to external builtin %s in function, which is not supported by "
+                  "eBPF", name != NULL_TREE ? IDENTIFIER_POINTER (name) : "(anon)");
+           output_asm_insn ("call 0", NULL);
+         }
        else
          output_asm_insn ("call\t%0", &target);
 
@@ -765,6 +774,18 @@ bpf_output_call (rtx target)
   return "";
 }
 
+static void
+bpf_external_libcall (rtx fun)
+{
+  tree decl = SYMBOL_REF_DECL (fun);
+  tree name = DECL_NAME (decl);
+  error ("call to external libcall %s in function, which is not supported by "
+        "eBPF", name != NULL_TREE ? IDENTIFIER_POINTER (name) : "(anon)");
+}
+
+#undef  TARGET_ASM_EXTERNAL_LIBCALL
+#define TARGET_ASM_EXTERNAL_LIBCALL bpf_external_libcall
+
 /* Print register name according to assembly dialect.  In normal
    syntax registers are printed like %rN where N is the register
    number.

diff --git a/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c b/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
index 4036570ac6015f956741f56a7090d41c02c86163..fec720584e48aac303a2252f7b96e2dc4e970d6c 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
+++ b/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
@@ -6,7 +6,7 @@ foo (int *p, int *expected, int desired)
 {
   return __atomic_compare_exchange (p, expected, &desired, 0,
                                    __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
-}
+} /* { dg-error "call to external builtin" } */
 
 int
 foo64 (long *p, long *expected, long desired)

diff --git a/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c b/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
index 044a2f76474b8a086cb185f926766d0607c4e973..ea1b8e48928a83b0967008ec3ddd34b92673f5b4 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
+++ b/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
@@ -9,7 +9,7 @@ long
 test_atomic_fetch_add (long x)
 {
   return __atomic_fetch_add (&val, x, __ATOMIC_ACQUIRE);
-}
+} /* { dg-error "call to external builtin" } */
 
 long
 test_atomic_fetch_sub (long x)

diff --git a/gcc/testsuite/gcc.target/bpf/atomic-op-3.c b/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
index b2ce28926347b7956040f61b5e273fec6b657c6c..fefafd6b748f8d41faaf6be694c7478c3a97cf69 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
+++ b/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
@@ -20,7 +20,7 @@ void
 test_atomic_and (int x)
 {
   __atomic_and_fetch (&val, x, __ATOMIC_ACQUIRE);
-}
+} /* { dg-error "call to external builtin" } */
 
 void
 test_atomic_nand (int x)

diff --git a/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c b/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
index 3b6324e966b85bd31613fb9000e7bcc022f52020..eab695bf388cdb7482f6308a831b13a2b63bb18f 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
+++ b/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
@@ -7,7 +7,7 @@ int foo (int *p, int *new)
   int old;
   __atomic_exchange (p, new, &old, __ATOMIC_RELAXED);
   return old;
-}
+} /* { dg-error "call to external builtin" } */
 
 int foo64 (long *p, long *new)
 {

diff --git a/gcc/testsuite/gcc.target/bpf/diag-sdiv.c b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
index c48bbf03df976ef8ce875fa9692fc1396fecfd1e..c3332558e7d265dd71d4baf8351764c4958d939c 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
+++ b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
@@ -7,6 +7,6 @@ foo ()
 {
   signed int x = 5;
   signed int y = 2;
-  signed int z = x / y;
+  signed int z = x / y; /* { dg-error "call to external libcall" } */
 }
 /* { dg-final { scan-assembler-not "sdiv(32)?\t%r" } } */

diff --git a/gcc/testsuite/gcc.target/bpf/diag-smod.c b/gcc/testsuite/gcc.target/bpf/diag-smod.c
index d3df308217f3322ecb0c97599c0ad604a218fc3e..25bcb1e4ffdb9e7d5493537fcc4642f0f1081238 100644 (file)
--- a/gcc/testsuite/gcc.target/bpf/diag-smod.c
+++ b/gcc/testsuite/gcc.target/bpf/diag-smod.c
@@ -7,6 +7,6 @@ foo ()
 {
   signed int x = 5;
   signed int y = 2;
-  signed int z = x % y;
+  signed int z = x % y; /* { dg-error "call to external libcall" } */
 }
 /* { dg-final { scan-assembler-not "smod(32)?\t%r" } } */