From 6d2cf69f91217e98712bf2c66a1f9fea3271b945 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Sat, 18 Nov 2000 00:13:28 +0000 Subject: * ehopt.c (eh_frame_code_alignment): New arg `in_seg', update all callers. Don't switch segments. Expect CIE == -1 in .debug_frame. (check_eh_frame): Handle .eh_frame and .debug_frame concurrently. --- gas/ehopt.c | 131 ++++++++++++++++++++++++++++++++++-------------------------- 1 file changed, 75 insertions(+), 56 deletions(-) (limited to 'gas/ehopt.c') diff --git a/gas/ehopt.c b/gas/ehopt.c index 03d7a04..6751827 100644 --- a/gas/ehopt.c +++ b/gas/ehopt.c @@ -31,13 +31,17 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA /* Try to optimize gcc 2.8 exception frame information. Exception frame information is emitted for every function in the - .eh_frame section. Simple information for a function with no - exceptions looks like this: + .eh_frame or .debug_frame sections. Simple information for a function + with no exceptions looks like this: __FRAME_BEGIN__: .4byte .LLCIE1 / Length of Common Information Entry .LSCIE1: +#if .eh_frame .4byte 0x0 / CIE Identifier Tag +#elif .debug_frame + .4byte 0xffffffff / CIE Identifier Tag +#endif .byte 0x1 / CIE Version .byte 0x0 / CIE Augmentation (none) .byte 0x1 / ULEB128 0x1 (CIE Code Alignment Factor) @@ -84,30 +88,33 @@ __FRAME_BEGIN__: not know this value, it always uses four bytes. We will know the value at the end of assembly, so we can do better. */ -static int eh_frame_code_alignment PARAMS ((void)); +static int eh_frame_code_alignment PARAMS ((int)); /* Get the code alignment factor from the CIE. */ static int -eh_frame_code_alignment () +eh_frame_code_alignment (in_seg) + int in_seg; { + /* ??? Assume .eh_frame and .debug_frame have the same alignment. */ static int code_alignment; - segT current_seg; - subsegT current_subseg; + fragS *f; fixS *fix; int offset; + char CIE_id; char augmentation[10]; int iaug; if (code_alignment != 0) return code_alignment; - /* We should find the CIE at the start of the .eh_frame section. */ + /* Can't find the alignment if we've changed sections. */ + if (! in_seg) + return -1; + + /* We should find the CIE at the start of the section. */ - current_seg = now_seg; - current_subseg = now_subseg; - subseg_new (".eh_frame", 0); #if defined (BFD_ASSEMBLER) || defined (MANY_SEGMENTS) f = seg_info (now_seg)->frchainP->frch_root; #else @@ -118,11 +125,15 @@ eh_frame_code_alignment () #else fix = *seg_fix_rootP; #endif - subseg_set (current_seg, current_subseg); /* Look through the frags of the section to find the code alignment. */ - /* First make sure that the CIE Identifier Tag is 0. */ + /* First make sure that the CIE Identifier Tag is 0/-1. */ + + if (strcmp (segment_name (now_seg), ".debug_frame") == 0) + CIE_id = (char)0xff; + else + CIE_id = 0; offset = 4; while (f != NULL && offset >= f->fr_fix) @@ -132,10 +143,10 @@ eh_frame_code_alignment () } if (f == NULL || f->fr_fix - offset < 4 - || f->fr_literal[offset] != 0 - || f->fr_literal[offset + 1] != 0 - || f->fr_literal[offset + 2] != 0 - || f->fr_literal[offset + 3] != 0) + || f->fr_literal[offset] != CIE_id + || f->fr_literal[offset + 1] != CIE_id + || f->fr_literal[offset + 2] != CIE_id + || f->fr_literal[offset + 3] != CIE_id) { code_alignment = -1; return -1; @@ -261,33 +272,42 @@ check_eh_frame (exp, pnbytes) expressionS *exp; unsigned int *pnbytes; { - static int saw_size; - static symbolS *size_end_sym; - static int saw_advance_loc4; - static fragS *loc4_frag; - static int loc4_fix; - - if (saw_size - && S_IS_DEFINED (size_end_sym)) + struct frame_data + { + symbolS *size_end_sym; + fragS *loc4_frag; + int saw_size; + int saw_advance_loc4; + int loc4_fix; + }; + + static struct frame_data eh_frame_data; + static struct frame_data debug_frame_data; + struct frame_data *d; + + /* Don't optimize. */ + if (flag_traditional_format) + return 0; + + /* Select the proper section data. */ + if (strcmp (segment_name (now_seg), ".eh_frame") == 0) + d = &eh_frame_data; + else if (strcmp (segment_name (now_seg), ".debug_frame") == 0) + d = &debug_frame_data; + else + return 0; + + if (d->saw_size && S_IS_DEFINED (d->size_end_sym)) { /* We have come to the end of the CIE or FDE. See below where we set saw_size. We must check this first because we may now be looking at the next size. */ - saw_size = 0; - saw_advance_loc4 = 0; + d->saw_size = 0; + d->saw_advance_loc4 = 0; } - if (flag_traditional_format) - { - /* Don't optimize. */ - } - else if (strcmp (segment_name (now_seg), ".eh_frame") != 0) - { - saw_size = 0; - saw_advance_loc4 = 0; - } - else if (! saw_size - && *pnbytes == 4) + if (! d->saw_size + && *pnbytes == 4) { /* This might be the size of the CIE or FDE. We want to know the size so that we don't accidentally optimize across an FDE @@ -301,23 +321,23 @@ check_eh_frame (exp, pnbytes) if ((exp->X_op == O_symbol || exp->X_op == O_subtract) && ! S_IS_DEFINED (exp->X_add_symbol)) { - saw_size = 1; - size_end_sym = exp->X_add_symbol; + d->saw_size = 1; + d->size_end_sym = exp->X_add_symbol; } } - else if (saw_size + else if (d->saw_size && *pnbytes == 1 && exp->X_op == O_constant && exp->X_add_number == DW_CFA_advance_loc4) { /* This might be a DW_CFA_advance_loc4. Record the frag and the position within the frag, so that we can change it later. */ - saw_advance_loc4 = 1; + d->saw_advance_loc4 = 1; frag_grow (1); - loc4_frag = frag_now; - loc4_fix = frag_now_fix (); + d->loc4_frag = frag_now; + d->loc4_fix = frag_now_fix (); } - else if (saw_advance_loc4 + else if (d->saw_advance_loc4 && *pnbytes == 4 && exp->X_op == O_constant) { @@ -328,9 +348,9 @@ check_eh_frame (exp, pnbytes) reduced to a constant. We can do the optimization entirely in this function. */ - saw_advance_loc4 = 0; + d->saw_advance_loc4 = 0; - ca = eh_frame_code_alignment (); + ca = eh_frame_code_alignment (1); if (ca < 0) { /* Don't optimize. */ @@ -338,41 +358,40 @@ check_eh_frame (exp, pnbytes) else if (exp->X_add_number % ca == 0 && exp->X_add_number / ca < 0x40) { - loc4_frag->fr_literal[loc4_fix] + d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc | (exp->X_add_number / ca); /* No more bytes needed. */ return 1; } else if (exp->X_add_number < 0x100) { - loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc1; + d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc1; *pnbytes = 1; } else if (exp->X_add_number < 0x10000) { - loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc2; + d->loc4_frag->fr_literal[d->loc4_fix] = DW_CFA_advance_loc2; *pnbytes = 2; } } - else if (saw_advance_loc4 + else if (d->saw_advance_loc4 && *pnbytes == 4 && exp->X_op == O_subtract) { - /* This is a case we can optimize. The expression was not reduced, so we can not finish the optimization until the end of the assembly. We set up a variant frag which we handle later. */ - saw_advance_loc4 = 0; + d->saw_advance_loc4 = 0; frag_var (rs_cfa, 4, 0, 0, make_expr_symbol (exp), - loc4_fix, (char *) loc4_frag); + d->loc4_fix, (char *) d->loc4_frag); return 1; } else - saw_advance_loc4 = 0; + d->saw_advance_loc4 = 0; return 0; } @@ -389,7 +408,7 @@ eh_frame_estimate_size_before_relax (frag) offsetT diff; int ret; - ca = eh_frame_code_alignment (); + ca = eh_frame_code_alignment (0); diff = resolve_symbol_value (frag->fr_symbol, 0); if (ca < 0) @@ -444,7 +463,7 @@ eh_frame_convert_frag (frag) { int ca; - ca = eh_frame_code_alignment (); + ca = eh_frame_code_alignment (0); assert (ca > 0 && diff % ca == 0 && diff / ca < 0x40); loc4_frag->fr_literal[loc4_fix] = DW_CFA_advance_loc | (diff / ca); } -- cgit v1.1