From b3cd99cdbddd9828860494676262ea45513a7830 Mon Sep 17 00:00:00 2001 From: Eric Botcazou Date: Sat, 25 Oct 2003 14:55:18 +0200 Subject: re PR target/12712 (ICE on short legit C++ code fragment with gcc 3.3.2) PR target/12712 * reg-stack.c (convert_regs_1): Create an arbitrary input stack if the block has no predecessors. (convert_regs_2): Document the problem with successors whose only predecessor is the block to be processed. (convert_regs): Don't create the arbitrary input stack here. From-SVN: r72923 --- gcc/reg-stack.c | 49 ++++++++++++++++++++++++++++++------------------- 1 file changed, 30 insertions(+), 19 deletions(-) (limited to 'gcc/reg-stack.c') diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c index fe1bc23..50bc63f 100644 --- a/gcc/reg-stack.c +++ b/gcc/reg-stack.c @@ -2675,10 +2675,24 @@ convert_regs_1 (FILE *file, basic_block block) beste = e; } - /* Entry block does have stack already initialized. */ + /* Initialize stack at block entry. */ if (bi->stack_in.top == -2) - inserted |= compensate_edge (beste, file); + { + if (beste) + inserted |= compensate_edge (beste, file); + else + { + /* No predecessors. Create an arbitrary input stack. */ + int reg; + + bi->stack_in.top = -1; + for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg) + if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg)) + bi->stack_in.reg[++bi->stack_in.top] = reg; + } + } else + /* Entry blocks do have stack already initialized. */ beste = NULL; current_block = block; @@ -2833,12 +2847,19 @@ convert_regs_2 (FILE *file, basic_block block) block = *--sp; - /* Processing "block" is achieved by convert_regs_1, which may purge - some dead EH outgoing edge after the possible deletion of the - trapping insn inside the block. Since the number of predecessors of - "block"'s successors has been computed based on the initial edge set, - we check for the possibility to process some of these successors - before such an edge deletion may happen. */ + /* Processing BLOCK is achieved by convert_regs_1, which may purge + some dead EH outgoing edge after the deletion of the trapping + insn inside the block. Since the number of predecessors of + BLOCK's successors was computed based on the initial edge set, + we check the necessity to process some of these successors + before such an edge deletion may happen. However, there is + a pitfall: if BLOCK is the only predecessor of a successor and + the edge between them happens to be deleted, the successor + becomes unreachable and should not be processed. The problem + is that there is no way to preventively detect this case so we + stack the successor in all cases and hand over the task of + fixing up the discrepancy to convert_regs_1. */ + for (e = block->succ; e ; e = e->succ_next) if (! (e->flags & EDGE_DFS_BACK)) { @@ -2888,17 +2909,7 @@ convert_regs (FILE *file) block_info bi = BLOCK_INFO (b); if (! bi->done) - { - int reg; - - /* Create an arbitrary input stack. */ - bi->stack_in.top = -1; - for (reg = LAST_STACK_REG; reg >= FIRST_STACK_REG; --reg) - if (TEST_HARD_REG_BIT (bi->stack_in.reg_set, reg)) - bi->stack_in.reg[++bi->stack_in.top] = reg; - - inserted |= convert_regs_2 (file, b); - } + inserted |= convert_regs_2 (file, b); } clear_aux_for_blocks (); -- cgit v1.1