forked from Mirrors/tinycc
a lot simpler VLA code
Author: Philip <pipcet@gmail.com>
Our VLA code can be made a lot simpler (simple enough for
even me to understand it) by giving up on the optimization idea, which
is very tempting. There's a patch to do that attached, feel free to
test and commit it if you like. (It passes all the tests, at least
master
seyko
parent
fca58734fb
commit
999274ca90
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@ -1126,11 +1126,7 @@ ST_FUNC void gen_vla_alloc(CType *type, int align) {
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/* We align to 16 bytes rather than align */
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/* and ~15, %esp */
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o(0xf0e483);
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/* mov %esp, r */
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o(0x89);
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o(0xe0 | r);
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vpop();
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vset(type, r, 0);
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#endif
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}
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6
tcc.h
6
tcc.h
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@ -464,12 +464,6 @@ typedef struct DLLReference {
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#define SYM_FIELD 0x20000000 /* struct/union field symbol space */
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#define SYM_FIRST_ANOM 0x10000000 /* first anonymous sym */
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#define VLA_SP_LOC_SET 0x01 /* Location of SP on stack has been allocated */
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#define VLA_SP_SAVED 0x02 /* SP has been saved to slot already */
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#define VLA_NEED_NEW_FRAME 0x04 /* Needs new frame for next VLA */
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#define VLA_IN_SCOPE 0x08 /* One or more VLAs are in scope */
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#define VLA_SCOPE_FLAGS (VLA_SP_SAVED|VLA_NEED_NEW_FRAME|VLA_IN_SCOPE) /* Flags which are saved and restored upon entering and exiting a block */
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/* stored in 'Sym.c' field */
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#define FUNC_NEW 1 /* ansi function prototype */
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#define FUNC_OLD 2 /* old function prototype */
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113
tccgen.c
113
tccgen.c
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@ -55,10 +55,9 @@ ST_DATA Sym *define_stack;
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ST_DATA Sym *global_label_stack;
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ST_DATA Sym *local_label_stack;
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ST_DATA int vla_sp_loc_tmp; /* vla_sp_loc is set to this when the value won't be needed later */
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ST_DATA int vlas_in_scope; /* number of VLAs that are currently in scope */
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ST_DATA int vla_sp_root_loc; /* vla_sp_loc for SP before any VLAs were pushed */
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ST_DATA int *vla_sp_loc; /* Pointer to variable holding location to store stack pointer on the stack when modifying stack pointer */
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ST_DATA int vla_flags; /* VLA_* flags */
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ST_DATA int vla_sp_loc; /* Pointer to variable holding location to store stack pointer on the stack when modifying stack pointer */
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ST_DATA SValue __vstack[1+VSTACK_SIZE], *vtop;
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@ -87,7 +86,8 @@ static int decl0(int l, int is_for_loop_init);
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static void expr_eq(void);
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static void unary_type(CType *type);
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static void vla_runtime_type_size(CType *type, int *a);
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static void vla_sp_save(void);
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static void vla_sp_restore(void);
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static void vla_sp_restore_root(void);
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static int is_compatible_parameter_types(CType *type1, CType *type2);
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static void expr_type(CType *type);
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ST_FUNC void vpush64(int ty, unsigned long long v);
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@ -2223,14 +2223,15 @@ ST_FUNC void vla_runtime_type_size(CType *type, int *a)
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}
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}
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static void vla_sp_save(void) {
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if (!(vla_flags & VLA_SP_LOC_SET)) {
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*vla_sp_loc = (loc -= PTR_SIZE);
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vla_flags |= VLA_SP_LOC_SET;
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static void vla_sp_restore(void) {
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if (vlas_in_scope) {
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gen_vla_sp_restore(vla_sp_loc);
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}
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if (!(vla_flags & VLA_SP_SAVED)) {
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gen_vla_sp_save(*vla_sp_loc);
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vla_flags |= VLA_SP_SAVED;
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}
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static void vla_sp_restore_root(void) {
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if (vlas_in_scope) {
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gen_vla_sp_restore(vla_sp_root_loc);
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}
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}
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@ -4794,10 +4795,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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} else if (tok == TOK_WHILE) {
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next();
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d = ind;
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if (vla_flags & VLA_IN_SCOPE) {
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gen_vla_sp_restore(*vla_sp_loc);
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vla_flags |= VLA_NEED_NEW_FRAME;
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}
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vla_sp_restore();
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skip('(');
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gexpr();
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skip(')');
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@ -4809,7 +4807,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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gsym_addr(b, d);
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} else if (tok == '{') {
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Sym *llabel;
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int block_vla_sp_loc, *saved_vla_sp_loc, saved_vla_flags, *orig_vla_sp_loc;
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int block_vla_sp_loc = vla_sp_loc, saved_vlas_in_scope = vlas_in_scope;
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next();
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/* record local declaration stack position */
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@ -4819,15 +4817,6 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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scope_stack_bottom = frame_bottom;
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llabel = local_label_stack;
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/* save VLA state */
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block_vla_sp_loc = *(saved_vla_sp_loc = vla_sp_loc);
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if (saved_vla_sp_loc != &vla_sp_root_loc)
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vla_sp_loc = &block_vla_sp_loc;
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orig_vla_sp_loc = vla_sp_loc;
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saved_vla_flags = vla_flags;
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vla_flags |= VLA_NEED_NEW_FRAME;
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/* handle local labels declarations */
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if (tok == TOK_LABEL) {
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next();
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@ -4877,13 +4866,11 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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sym_pop(&local_stack, s);
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/* Pop VLA frames and restore stack pointer if required */
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if (saved_vla_sp_loc != &vla_sp_root_loc)
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*saved_vla_sp_loc = block_vla_sp_loc;
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if (vla_sp_loc != orig_vla_sp_loc) {
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gen_vla_sp_restore(*saved_vla_sp_loc);
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if (vlas_in_scope > saved_vlas_in_scope) {
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vla_sp_loc = saved_vlas_in_scope ? block_vla_sp_loc : vla_sp_root_loc;
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vla_sp_restore();
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}
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vla_sp_loc = saved_vla_sp_loc;
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vla_flags = (vla_flags & ~VLA_SCOPE_FLAGS) | (saved_vla_flags & VLA_SCOPE_FLAGS);
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vlas_in_scope = saved_vlas_in_scope;
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next();
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} else if (tok == TOK_RETURN) {
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@ -4964,13 +4951,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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/* compute jump */
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if (!csym)
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tcc_error("cannot continue");
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if (vla_flags & VLA_IN_SCOPE) {
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/* If VLAs are in use, save the current stack pointer and
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reset the stack pointer to what it was at function entry
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(label will restore stack pointer in inner scopes) */
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vla_sp_save();
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gen_vla_sp_restore(vla_sp_root_loc);
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}
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vla_sp_restore_root();
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*csym = gjmp(*csym);
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next();
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skip(';');
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@ -4993,10 +4974,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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skip(';');
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d = ind;
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c = ind;
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if (vla_flags & VLA_IN_SCOPE) {
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gen_vla_sp_restore(*vla_sp_loc);
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vla_flags |= VLA_NEED_NEW_FRAME;
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}
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vla_sp_restore();
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a = 0;
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b = 0;
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if (tok != ';') {
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@ -5007,10 +4985,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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if (tok != ')') {
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e = gjmp(0);
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c = ind;
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if (vla_flags & VLA_IN_SCOPE) {
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gen_vla_sp_restore(*vla_sp_loc);
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vla_flags |= VLA_NEED_NEW_FRAME;
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}
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vla_sp_restore();
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gexpr();
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vpop();
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gjmp_addr(d);
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@ -5029,10 +5004,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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a = 0;
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b = 0;
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d = ind;
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if (vla_flags & VLA_IN_SCOPE) {
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gen_vla_sp_restore(*vla_sp_loc);
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vla_flags |= VLA_NEED_NEW_FRAME;
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}
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vla_sp_restore();
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block(&a, &b, case_sym, def_sym, case_reg, 0);
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skip(TOK_WHILE);
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skip('(');
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@ -5130,14 +5102,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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if (s->r == LABEL_DECLARED)
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s->r = LABEL_FORWARD;
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}
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/* label already defined */
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if (vla_flags & VLA_IN_SCOPE) {
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/* If VLAs are in use, save the current stack pointer and
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reset the stack pointer to what it was at function entry
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(label will restore stack pointer in inner scopes) */
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vla_sp_save();
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gen_vla_sp_restore(vla_sp_root_loc);
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}
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vla_sp_restore_root();
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if (s->r & LABEL_FORWARD)
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s->jnext = gjmp(s->jnext);
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else
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@ -5153,12 +5118,6 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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b = is_label();
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if (b) {
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/* label case */
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if (vla_flags & VLA_IN_SCOPE) {
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/* save/restore stack pointer across label
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this is a no-op when combined with the load immediately
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after the label unless we arrive via goto */
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vla_sp_save();
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}
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s = label_find(b);
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if (s) {
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if (s->r == LABEL_DEFINED)
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@ -5169,10 +5128,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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s = label_push(&global_label_stack, b, LABEL_DEFINED);
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}
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s->jnext = ind;
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if (vla_flags & VLA_IN_SCOPE) {
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gen_vla_sp_restore(*vla_sp_loc);
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vla_flags |= VLA_NEED_NEW_FRAME;
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}
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vla_sp_restore();
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/* we accept this, but it is a mistake */
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block_after_label:
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if (tok == '}') {
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@ -5476,20 +5432,17 @@ static void decl_initializer(CType *type, Section *sec, unsigned long c,
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int a;
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/* save current stack pointer */
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if (vla_flags & VLA_NEED_NEW_FRAME) {
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vla_sp_save();
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vla_flags = VLA_IN_SCOPE;
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vla_sp_loc = &vla_sp_loc_tmp;
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if (vlas_in_scope == 0) {
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if (vla_sp_root_loc == -1)
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vla_sp_root_loc = (loc -= PTR_SIZE);
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gen_vla_sp_save(vla_sp_root_loc);
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}
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vla_runtime_type_size(type, &a);
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gen_vla_alloc(type, a);
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vla_flags = VLA_IN_SCOPE;
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vla_sp_save();
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vset(type, VT_LOCAL|VT_LVAL, c);
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vswap();
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vstore();
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vpop();
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gen_vla_sp_save(c);
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vla_sp_loc = c;
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vlas_in_scope++;
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} else if (type->t & VT_ARRAY) {
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s = type->ref;
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n = s->c;
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@ -6072,8 +6025,8 @@ static void gen_function(Sym *sym)
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funcname = get_tok_str(sym->v, NULL);
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func_ind = ind;
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/* Initialize VLA state */
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vla_sp_loc = &vla_sp_root_loc;
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vla_flags = VLA_NEED_NEW_FRAME;
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vla_sp_loc = -1;
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vla_sp_root_loc = -1;
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/* put debug symbol */
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if (tcc_state->do_debug)
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put_func_debug(sym);
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@ -2240,11 +2240,7 @@ ST_FUNC void gen_vla_alloc(CType *type, int align) {
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/* We align to 16 bytes rather than align */
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/* and ~15, %rsp */
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o(0xf0e48348);
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/* mov %rsp, r */
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o(0x8948);
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o(0xe0 | REG_VALUE(r));
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vpop();
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vset(type, r, 0);
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#endif
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}
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