The sibling call optimisation shouldn't prevent functions from being
lazily bound. This was a problem for n32 and n64 PIC, because MIPS
lazy binding stubs require $gp to be valid on entry, and because $gp
is a call-saved register. (o32 is OK because $gp is call-clobbered.)
I was going to remove the MIPS_CALL_SIBCALL check in:
/* If we're generating PIC, and this call is to a global function,
try to allow its address to be resolved lazily. This isn't
possible for sibcalls when $gp is call-saved because the value
of $gp on entry to the stub would be our caller's gp, not ours. */
if (TARGET_EXPLICIT_RELOCS
&& !(type == MIPS_CALL_SIBCALL && TARGET_CALL_SAVED_GP)
&& mips_ok_for_lazy_binding_p (addr))
{
addr = mips_got_load (dest, addr, SYMBOL_GOTOFF_CALL);
emit_insn (gen_rtx_SET (VOIDmode, dest, addr));
return true;
}
but it is also used for sibling-style calls in C++ thunks. I think
it's valid to override lazy binding in that case, since vtables
prevent lazy binding anyway.
Tested on mips64-linux-gnu and applied.
Richard
gcc/
PR target/57260
* config/mips/mips.c (mips_function_ok_for_sibcall): Don't allow
sibling calls to functions that would normally be lazily bound,
unless $gp is call-clobbered.
gcc/testsuite/
PR target/57260
* gcc.target/mips/call-1.c: Restrict to o32.
* gcc.target/mips/call-5.c, gcc.target/mips/call-6.c: New test.
Index: gcc/config/mips/mips.c
===================================================================
--- gcc/config/mips/mips.c 2013-05-14 19:25:06.061932211 +0100
+++ gcc/config/mips/mips.c 2013-05-14 20:21:56.647243683 +0100
@@ -6995,6 +6995,15 @@ mips_function_ok_for_sibcall (tree decl,
&& mips_call_may_need_jalx_p (decl))
return false;
+ /* Sibling calls should not prevent lazy binding. Lazy-binding stubs
+ require $gp to be valid on entry, so sibcalls can only use stubs
+ if $gp is call-clobbered. */
+ if (decl
+ && TARGET_CALL_SAVED_GP
+ && !TARGET_ABICALLS_PIC0
+ && !targetm.binds_local_p (decl))
+ return false;
+
/* Otherwise OK. */
return true;
}
Index: gcc/testsuite/gcc.target/mips/call-1.c
===================================================================
--- gcc/testsuite/gcc.target/mips/call-1.c 2012-08-27 17:27:13.000000000
+0100
+++ gcc/testsuite/gcc.target/mips/call-1.c 2013-05-14 19:51:06.188573399
+0100
@@ -1,10 +1,12 @@
-/* { dg-options "-mrelax-pic-calls -mshared -foptimize-sibling-calls" } */
+/* { dg-options "-mrelax-pic-calls -mshared -foptimize-sibling-calls -mabi=32"
} */
/* { dg-skip-if "requires -foptimize-sibling-calls" { *-*-* } { "-O0" } { "" }
} */
/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal\n1:\tjalr\t" }
} */
/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal2\n1:\tjalr\t"
} } */
/* { dg-final { scan-assembler
"\\.reloc\t1f,R_MIPS_JALR,staticfunc\n1:\tjalr\t" } } */
/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail\n1:\tjr\t" } } */
/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail2\n1:\tjr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail3\n1:\tjr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail4\n1:\tjr\t" } }
*/
__attribute__ ((noinline)) static void staticfunc () { asm (""); }
int normal ();
@@ -31,3 +33,17 @@ NOMIPS16 void g ()
{
tail2 ();
}
+
+__attribute__ ((visibility ("hidden"))) void tail3 ();
+
+NOMIPS16 void j ()
+{
+ tail3 ();
+}
+
+__attribute__ ((noinline)) static void tail4 () { asm (""); }
+
+NOMIPS16 void k ()
+{
+ tail4 ();
+}
Index: gcc/testsuite/gcc.target/mips/call-5.c
===================================================================
--- /dev/null 2013-05-10 09:05:06.836922288 +0100
+++ gcc/testsuite/gcc.target/mips/call-5.c 2013-05-14 19:51:01.492525330
+0100
@@ -0,0 +1,51 @@
+/* Like call-1.c, but for n32. We cannot use sibling calls for tail and tail2
+ in this case (PR target/57260). */
+/* { dg-options "-mrelax-pic-calls -mshared -foptimize-sibling-calls
-mabi=n32" } */
+/* { dg-skip-if "requires -foptimize-sibling-calls" { *-*-* } { "-O0" } { "" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal\n1:\tjalr\t" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal2\n1:\tjalr\t"
} } */
+/* { dg-final { scan-assembler
"\\.reloc\t1f,R_MIPS_JALR,staticfunc\n1:\tjalr\t" } } */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail\n1:\tjalr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail2\n1:\tjalr\t" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail3\n1:\tjr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail4\n1:\tjr\t" } }
*/
+
+__attribute__ ((noinline)) static void staticfunc () { asm (""); }
+int normal ();
+void normal2 ();
+
+NOMIPS16 f (int *p)
+{
+ *p = normal ();
+ normal2 ();
+ staticfunc ();
+ return 1;
+}
+
+int tail ();
+
+NOMIPS16 h ()
+{
+ return tail ();
+}
+
+void tail2 ();
+
+NOMIPS16 void g ()
+{
+ tail2 ();
+}
+
+__attribute__ ((visibility ("hidden"))) void tail3 ();
+
+NOMIPS16 void j ()
+{
+ tail3 ();
+}
+
+__attribute__ ((noinline)) static void tail4 () { asm (""); }
+
+NOMIPS16 void k ()
+{
+ tail4 ();
+}
Index: gcc/testsuite/gcc.target/mips/call-6.c
===================================================================
--- /dev/null 2013-05-10 09:05:06.836922288 +0100
+++ gcc/testsuite/gcc.target/mips/call-6.c 2013-05-14 20:15:08.281988889
+0100
@@ -0,0 +1,50 @@
+/* Like call-5.c, but for n64. */
+/* { dg-options "-mrelax-pic-calls -mshared -foptimize-sibling-calls -mabi=64"
} */
+/* { dg-skip-if "requires -foptimize-sibling-calls" { *-*-* } { "-O0" } { "" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal\n1:\tjalr\t" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,normal2\n1:\tjalr\t"
} } */
+/* { dg-final { scan-assembler
"\\.reloc\t1f,R_MIPS_JALR,staticfunc\n1:\tjalr\t" } } */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail\n1:\tjalr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail2\n1:\tjalr\t" }
} */
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail3\n1:\tjr\t" } }
*/
+/* { dg-final { scan-assembler "\\.reloc\t1f,R_MIPS_JALR,tail4\n1:\tjr\t" } }
*/
+
+__attribute__ ((noinline)) static void staticfunc () { asm (""); }
+int normal ();
+void normal2 ();
+
+NOMIPS16 f (int *p)
+{
+ *p = normal ();
+ normal2 ();
+ staticfunc ();
+ return 1;
+}
+
+int tail ();
+
+NOMIPS16 h ()
+{
+ return tail ();
+}
+
+void tail2 ();
+
+NOMIPS16 void g ()
+{
+ tail2 ();
+}
+
+__attribute__ ((visibility ("hidden"))) void tail3 ();
+
+NOMIPS16 void j ()
+{
+ tail3 ();
+}
+
+__attribute__ ((noinline)) static void tail4 () { asm (""); }
+
+NOMIPS16 void k ()
+{
+ tail4 ();
+}
