| Message ID | CAFULd4arq=O1_3pOFXFTzQ16DH=ZZyA8mnT00KDNSo73OteQCQ@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Nov 25, 2014 at 09:13:10AM +0100, Uros Bizjak wrote: > On Tue, Nov 25, 2014 at 8:40 AM, Uros Bizjak <ubizjak@gmail.com> wrote: > > On Tue, Nov 25, 2014 at 12:25 AM, Jakub Jelinek <jakub@redhat.com> wrote: > > > >> The fallback delegitimization I've added as last option mainly for > >> debug info purposes, when we don't know if the base is a PIC register > >> or say a PIC register plus some addend, unfortunately in some tests > >> broke find_base_term, which for PLUS looks only at the first operand > >> and recursion on it finds a base term, it returns it immediately. > >> So, it found base term of _GLOBAL_OFFSET_TABLE_, when the right base > >> term is actually in the second operand. > >> > >> This patch fixes it by swapping the operands, debug info doesn't care about > >> the order, it won't match in any instruction anyway, but helps alias.c. > >> > >> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > >> > >> 2014-11-24 Jakub Jelinek <jakub@redhat.com> > >> > >> PR lto/64025 > >> * config/i386/i386.c (ix86_delegitimize_address): Ensure result > >> comes before (addend - _GLOBAL_OFFSET_TABLE_) term. > > > > Can you also swap operands of (%ecx - %ebx) + foo? There is no point > > digging into RTX involving registers only when we know that we are > > looking for foo. This will also be consistent with the code you > > patched below. > > Something like attached prototype patch. Actually, thinking about it more, at least according to commutative_operand_precedence the canonical order is what we used to return (i.e. (something - _G_O_T_) + (symbol_ref) or (something - _G_O_T_) + (const (symbol_ref +- const)) So perhaps better fix is to follow find_base_value, which does something like: /* Guess which operand is the base address: If either operand is a symbol, then it is the base. If either operand is a CONST_INT, then the other is the base. */ if (CONST_INT_P (src_1) || CONSTANT_P (src_0)) return find_base_value (src_0); else if (CONST_INT_P (src_0) || CONSTANT_P (src_1)) return find_base_value (src_1); and do something similar in find_base_term too. I.e. perhaps even with higher precedence over REG_P with REG_POINTER (or lower, in these cases it doesn't really matter, neither argument is REG_P), choose first operand that is CONSTANT_P and not CONST_INT_P. Jakub
Index: i386.c =================================================================== --- i386.c (revision 218037) +++ i386.c (working copy) @@ -14847,19 +14847,20 @@ ix86_delegitimize_address (rtx x) leal (%ebx, %ecx, 4), %ecx ... movl foo@GOTOFF(%ecx), %edx - in which case we return (%ecx - %ebx) + foo - or (%ecx - _GLOBAL_OFFSET_TABLE_) + foo if pseudo_pic_reg + in which case we return foo + (%ecx - %ebx) + or foo + (%ecx - _GLOBAL_OFFSET_TABLE_) if pseudo_pic_reg and reload has completed. */ if (pic_offset_table_rtx && (!reload_completed || !ix86_use_pseudo_pic_reg ())) - result = gen_rtx_PLUS (Pmode, gen_rtx_MINUS (Pmode, copy_rtx (addend), - pic_offset_table_rtx), - result); + result = gen_rtx_PLUS (Pmode, result, + gen_rtx_MINUS (Pmode, copy_rtx (addend), + pic_offset_table_rtx)); else if (pic_offset_table_rtx && !TARGET_MACHO && !TARGET_VXWORKS_RTP) { rtx tmp = gen_rtx_SYMBOL_REF (Pmode, GOT_SYMBOL_NAME); - tmp = gen_rtx_MINUS (Pmode, copy_rtx (addend), tmp); - result = gen_rtx_PLUS (Pmode, tmp, result); + result = gen_rtx_PLUS (Pmode, result, + gen_rtx_MINUS (Pmode, copy_rtx (addend), + tmp)); } else return orig_x;