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author | jdp <jdp@FreeBSD.org> | 1996-10-03 17:49:35 +0000 |
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committer | jdp <jdp@FreeBSD.org> | 1996-10-03 17:49:35 +0000 |
commit | b400b72e469a93b88555a568b89989a3fe8f3918 (patch) | |
tree | 37756f861451aa0a35128d1865b1e2285b2876c4 /contrib/gcc | |
parent | 5a3d59963e84a76fc6922009cb9032a42d5d0e88 (diff) | |
download | FreeBSD-src-b400b72e469a93b88555a568b89989a3fe8f3918.zip FreeBSD-src-b400b72e469a93b88555a568b89989a3fe8f3918.tar.gz |
Fix a bug that caused incorrect PIC code to be generated for exceptions.
The symptom was an assembler warning
"GOT relocation burb: `___EXCEPTION_TABLE__' should be global"
followed (sometimes) by a core dump. The fix makes the compiler
generate the correct GOTOFF addressing for that symbol, rather than the
GOT addressing it was emitting before.
Warning: There is still at least one serious bug in the i386 exception
code for PIC. The exception code that is generated clobbers the GOT
register (%ebx) and then tries to use it later. That leads to core
dumps at program execution time. I know where the problem is, but I do
not have a fix for it at this time. Until it is fixed, exceptions will
not work in PIC code. This is a general problem for all i386 platforms;
it is not specific to FreeBSD.
Diffstat (limited to 'contrib/gcc')
-rw-r--r-- | contrib/gcc/config/i386/i386.h | 16 | ||||
-rw-r--r-- | contrib/gcc/cp/except.c | 8 |
2 files changed, 23 insertions, 1 deletions
diff --git a/contrib/gcc/config/i386/i386.h b/contrib/gcc/config/i386/i386.h index b00b0e5..efc956a 100644 --- a/contrib/gcc/config/i386/i386.h +++ b/contrib/gcc/config/i386/i386.h @@ -1286,6 +1286,22 @@ do \ } \ while (0) +/* Define this macro if a SYMBOL_REF representing a non-global + address must be marked specially. This is called for + compiler-generated local symbols, such as "__EXCEPTION_TABLE__". + + On i386, if using PIC, we use this to set the rtx's + SYMBOL_REF_FLAG, so that we may access it directly as + an offset from the GOT register. */ + +#define MARK_LOCAL_ADDRESS(X) \ +do \ + { \ + if (flag_pic && GET_CODE (X) == SYMBOL_REF) \ + SYMBOL_REF_FLAG (X) = 1; \ + } \ +while (0) + /* Initialize data used by insn expanders. This is called from init_emit, once for each function, before code is generated. For 386, clear stack slot assignments remembered from previous diff --git a/contrib/gcc/cp/except.c b/contrib/gcc/cp/except.c index 51577f8..4443b98 100644 --- a/contrib/gcc/cp/except.c +++ b/contrib/gcc/cp/except.c @@ -1614,9 +1614,15 @@ emit_exception_table () void register_exception_table () { + rtx addr = gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__"); + +#ifdef MARK_LOCAL_ADDRESS + MARK_LOCAL_ADDRESS(addr); +#endif + emit_library_call (gen_rtx (SYMBOL_REF, Pmode, "__register_exceptions"), 0, VOIDmode, 1, - gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__"), + addr, Pmode); } |