| Message ID | 201006180402.05708.zorry@gentoo.org |
|---|---|
| State | New |
| Headers | show |
Magnus, Was this reviewed? If nobody offers to commit it, I will try to find some time to do it. Cheers, Manuel. On 18 June 2010 04:02, Magnus Granberg <zorry@gentoo.org> wrote: > söndag 30 maj 2010 02.21.53 skrev Magnus Granberg: >> torsdag 06 maj 2010 09.24.46 skrev Eric Botcazou: >> > It would be better to issue it from >> > >> > tree-nested.c:convert_tramp_reference_op so that it is attached to the >> > token that causes it to be created. For extra points, you could even >> > make >> > >> > it reference the nested function: >> > p2.adb: In function 'P2': >> > p2.adb:17:12: warning: trampoline generated for 'P2.F' >> > p2.adb:26:11: warning: address taken from here >> >> Have updated the patch to make two warnings one for the trampoline and the >> second one for makeing the stack executable. Did't add the reference to the >> nested function for extra points. Could not get the testcase ignore the >> second warning in the same line. >> > Have updated the patch. Can some one review it and commit it. > If the patch is okey. Tested on x86_64-unknown-linux-gnu > > /Magnus > ---- > 2010-06-18 Magnus Granberg <zorry@gentoo.org>, Kevin F. Quinn <kevquinn@gentoo.org> > > * builtins.c: (expand_builtin_init_trampoline): if warn_trampolines make a warning. > * common.opt: Add -Wtrampolines. > * varasm.c: (file_end_indicate_exec_stack): if warn_trampolines make a warning. > > gcc/doc > > 2010-06-18 Magnus Granberg <zorry@gentoo.org> > > * invoke.texi: Add -Wtrampolines. > > gcc/testsuite/ > > 2010-06-18 Magnus Granberg <zorry@gentoo.org> > > * gcc.dg/Wtrampolines.c: New. >
On Thu, Jun 17, 2010 at 9:02 PM, Magnus Granberg <zorry@gentoo.org> wrote: > söndag 30 maj 2010 02.21.53 skrev Magnus Granberg: >> torsdag 06 maj 2010 09.24.46 skrev Eric Botcazou: >> > It would be better to issue it from >> > >> > tree-nested.c:convert_tramp_reference_op so that it is attached to the >> > token that causes it to be created. For extra points, you could even >> > make >> > >> > it reference the nested function: >> > p2.adb: In function 'P2': >> > p2.adb:17:12: warning: trampoline generated for 'P2.F' >> > p2.adb:26:11: warning: address taken from here >> >> Have updated the patch to make two warnings one for the trampoline and the >> second one for makeing the stack executable. Did't add the reference to the >> nested function for extra points. Could not get the testcase ignore the >> second warning in the same line. >> > Have updated the patch. Can some one review it and commit it. > If the patch is okey. Tested on x86_64-unknown-linux-gnu > > /Magnus > ---- > 2010-06-18 Magnus Granberg <zorry@gentoo.org>, Kevin F. Quinn <kevquinn@gentoo.org> > > * builtins.c: (expand_builtin_init_trampoline): if warn_trampolines make a warning. > * common.opt: Add -Wtrampolines. > * varasm.c: (file_end_indicate_exec_stack): if warn_trampolines make a warning. > > gcc/doc > > 2010-06-18 Magnus Granberg <zorry@gentoo.org> > > * invoke.texi: Add -Wtrampolines. > > gcc/testsuite/ > > 2010-06-18 Magnus Granberg <zorry@gentoo.org> > > * gcc.dg/Wtrampolines.c: New. > Hi, I guess a question I have had since the beginning is: Why are you warning all the time a trampoline is generated, and not just for the case where the trampoline would require an executable stack?
gcc/ --- gcc/builtins.c.zorry 2010-04-13 15:47:11.000000000 +0200 +++ gcc/builtins.c 2010-06-16 12:33:54.000000000 +0200 @@ -5150,6 +5150,10 @@ targetm.calls.trampoline_init (m_tramp, t_func, r_chain); trampolines_created = 1; + + if (warn_trampolines) + warning (OPT_Wtrampolines, "trampoline generated for nested function %s", (IDENTIFIER_POINTER(DECL_NAME(t_func)))); + return const0_rtx; } --- gcc/common.opt.zorry 2010-03-18 04:01:09.000000000 +0100 +++ gcc/common.opt 2010-05-06 00:44:18.000000000 +0200 @@ -192,6 +192,10 @@ Common Var(warn_system_headers) Warning Do not suppress warnings from system headers +Wtrampolines +Common Var(warn_trampolines) Warnings +Warn whenever a trampoline is generated and warn if it requires executable stack to + Wtype-limits Common Var(warn_type_limits) Init(-1) Warning Warn if a comparison is always true or always false due to the limited range of the data type --- gcc/varasm.c.zorry 2010-03-27 12:56:30.000000000 +0100 +++ gcc/varasm.c 2010-05-29 15:06:33.000000000 +0200 @@ -6768,7 +6768,11 @@ { unsigned int flags = SECTION_DEBUG; if (trampolines_created) + { flags |= SECTION_CODE; + if (warn_trampolines) + warning (OPT_Wtrampolines, "setting the stack as executable stack"); + } switch_to_section (get_section (".note.GNU-stack", flags, NULL)); } --- gcc/doc/invoke.texi.zorry 2010-04-06 16:02:22.000000000 +0200 +++ gcc/doc/invoke.texi 2010-05-06 00:20:25.000000000 +0200 @@ -258,8 +258,8 @@ -Wstrict-aliasing -Wstrict-aliasing=n @gol -Wstrict-overflow -Wstrict-overflow=@var{n} @gol -Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand @gol --Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized @gol --Wunknown-pragmas -Wno-pragmas @gol +-Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef @gol +-Wuninitialized -Wunknown-pragmas -Wno-pragmas @gol -Wunsuffixed-float-constants -Wunused -Wunused-function @gol -Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol -Wvariadic-macros -Wvla @gol @@ -3603,6 +3603,19 @@ option will @emph{not} warn about unknown pragmas in system headers---for that, @option{-Wunknown-pragmas} must also be used. +@item -Wtrampolines +@opindex Wtrampolines +@opindex Wno-trampolines + Warn about trampolines generated for pointers to nested functions. + Warn when the trampoline requires the stack to be made executable. + + A trampoline is a small piece of data or code that is created at run + time on the stack when the address of a nested function is taken, and + is used to call the nested function indirectly. For some targets, it + is made up of data only and thus requires no special treatment. But, + for most targets, it is made up of code and thus requires the stack + to be made executable in order for the program to work properly. + @item -Wfloat-equal @opindex Wfloat-equal @opindex Wno-float-equal --- gcc/testsuite/gcc.dg/Wtrampolines.c.zorry 2010-05-05 12:53:11.000000000 +0200 +++ gcc/testsuite/gcc.dg/Wtrampolines.c 2010-05-06 00:26:05.000000000 +0200 @@ -0,0 +1,59 @@ +/* Origin: trampoline-1.c Waldek Hebisch <hebisch@math.uni.wroc.pl> */ +/* Ported to test -Wtrampolines Magnus Granberg <zorry@gentoo.org> */ + +/* { dg-do compile } */ +/* { dg-require-effective-target trampolines } */ +/* { dg-options "-O2 -Wtrampolines" } */ +/* { dg-warning "trampoline" "" { target *-*-* } 31 } */ +/* { dg-prune-output "stack" } */ + +#ifndef NO_TRAMPOLINES + +/* This used to fail on various versions of Solaris 2 because the + trampoline couldn't be made executable. */ + +extern void abort(void); +extern double fabs(double); + +void foo (void) +{ + const int correct[1100] = {1, 0, -2, 0, 1, 0, 1, -1, -10, -30, -67}; + int i; + + double x1 (void) {return 1; } + double x2 (void) {return -1;} + double x3 (void) {return -1;} + double x4 (void) {return 1; } + double x5 (void) {return 0; } + + typedef double pfun(void); + + double a (int k, pfun x1, pfun x2, pfun x3, pfun x4, pfun x5) + { + double b (void) + { + k = k - 1; + return a (k, b, x1, x2, x3, x4 ); + } + + if (k <= 0) + return x4 () + x5 (); + else + return b (); + } + + for (i=0; i<=10; i++) + { + if (fabs(a( i, x1, x2, x3, x4, x5 ) - correct [i]) > 0.1) + abort(); + } +} +#endif + +int main (void) +{ +#ifndef NO_TRAMPOLINES + foo (); +#endif + return 0; +}