Refactor VRP threading code into vrp_jump_threader class.
gcc/ChangeLog: * tree-vrp.c (identify_jump_threads): Refactor to.. (vrp_jump_threader::vrp_jump_threader): ...here (vrp_jump_threader::~vrp_jump_threader): ...and here. (vrp_jump_threader::after_dom_children): Rename vr_values to m_vr_values. (execute_vrp): Use vrp_jump_threader.
This commit is contained in:
Aldy Hernandez
parent
2efb9eaaed
commit
7cc52bc85e
144
gcc/tree-vrp.c
144
gcc/tree-vrp.c
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@ -4152,32 +4152,87 @@ vrp_prop::finalize ()
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}
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}
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/* Blocks which have more than one predecessor and more than
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one successor present jump threading opportunities, i.e.,
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when the block is reached from a specific predecessor, we
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may be able to determine which of the outgoing edges will
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be traversed. When this optimization applies, we are able
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to avoid conditionals at runtime and we may expose secondary
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optimization opportunities.
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This class is effectively a driver for the generic jump
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threading code. It basically just presents the generic code
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with edges that may be suitable for jump threading.
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Unlike DOM, we do not iterate VRP if jump threading was successful.
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While iterating may expose new opportunities for VRP, it is expected
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those opportunities would be very limited and the compile time cost
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to expose those opportunities would be significant.
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As jump threading opportunities are discovered, they are registered
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for later realization. */
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class vrp_jump_threader : public dom_walker
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{
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public:
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vrp_jump_threader (cdi_direction direction,
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class const_and_copies *const_and_copies,
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class avail_exprs_stack *avail_exprs_stack)
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: dom_walker (direction, REACHABLE_BLOCKS),
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m_const_and_copies (const_and_copies),
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m_avail_exprs_stack (avail_exprs_stack),
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m_dummy_cond (NULL) {}
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vrp_jump_threader (struct function *, vr_values *);
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~vrp_jump_threader ();
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virtual edge before_dom_children (basic_block);
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virtual void after_dom_children (basic_block);
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class vr_values *vr_values;
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void thread_jumps ()
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{
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walk (m_fun->cfg->x_entry_block_ptr);
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}
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private:
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static tree simplify_stmt (gimple *stmt, gimple *within_stmt,
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avail_exprs_stack *, basic_block);
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virtual edge before_dom_children (basic_block);
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virtual void after_dom_children (basic_block);
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class const_and_copies *m_const_and_copies;
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class avail_exprs_stack *m_avail_exprs_stack;
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function *m_fun;
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vr_values *m_vr_values;
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const_and_copies *m_const_and_copies;
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avail_exprs_stack *m_avail_exprs_stack;
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hash_table<expr_elt_hasher> *m_avail_exprs;
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gcond *m_dummy_cond;
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};
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vrp_jump_threader::vrp_jump_threader (struct function *fun, vr_values *v)
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: dom_walker (CDI_DOMINATORS, REACHABLE_BLOCKS)
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{
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/* Ugh. When substituting values earlier in this pass we can wipe
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the dominance information. So rebuild the dominator information
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as we need it within the jump threading code. */
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calculate_dominance_info (CDI_DOMINATORS);
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/* We do not allow VRP information to be used for jump threading
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across a back edge in the CFG. Otherwise it becomes too
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difficult to avoid eliminating loop exit tests. Of course
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EDGE_DFS_BACK is not accurate at this time so we have to
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recompute it. */
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mark_dfs_back_edges ();
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/* Allocate our unwinder stack to unwind any temporary equivalences
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that might be recorded. */
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m_const_and_copies = new const_and_copies ();
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m_dummy_cond = NULL;
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m_fun = fun;
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m_vr_values = v;
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m_avail_exprs = new hash_table<expr_elt_hasher> (1024);
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m_avail_exprs_stack = new avail_exprs_stack (m_avail_exprs);
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}
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vrp_jump_threader::~vrp_jump_threader ()
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{
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/* We do not actually update the CFG or SSA graphs at this point as
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ASSERT_EXPRs are still in the IL and cfg cleanup code does not
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yet handle ASSERT_EXPRs gracefully. */
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delete m_const_and_copies;
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delete m_avail_exprs;
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delete m_avail_exprs_stack;
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}
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/* Called before processing dominator children of BB. We want to look
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at ASSERT_EXPRs and record information from them in the appropriate
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tables.
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@ -4295,7 +4350,7 @@ vrp_jump_threader::after_dom_children (basic_block bb)
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integer_zero_node, integer_zero_node,
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NULL, NULL);
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x_vr_values = vr_values;
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x_vr_values = m_vr_values;
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thread_outgoing_edges (bb, m_dummy_cond, m_const_and_copies,
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m_avail_exprs_stack, NULL,
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simplify_stmt);
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@ -4305,62 +4360,6 @@ vrp_jump_threader::after_dom_children (basic_block bb)
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m_const_and_copies->pop_to_marker ();
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}
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/* Blocks which have more than one predecessor and more than
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one successor present jump threading opportunities, i.e.,
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when the block is reached from a specific predecessor, we
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may be able to determine which of the outgoing edges will
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be traversed. When this optimization applies, we are able
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to avoid conditionals at runtime and we may expose secondary
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optimization opportunities.
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This routine is effectively a driver for the generic jump
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threading code. It basically just presents the generic code
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with edges that may be suitable for jump threading.
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Unlike DOM, we do not iterate VRP if jump threading was successful.
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While iterating may expose new opportunities for VRP, it is expected
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those opportunities would be very limited and the compile time cost
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to expose those opportunities would be significant.
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As jump threading opportunities are discovered, they are registered
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for later realization. */
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static void
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identify_jump_threads (struct function *fun, class vr_values *vr_values)
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{
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/* Ugh. When substituting values earlier in this pass we can
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wipe the dominance information. So rebuild the dominator
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information as we need it within the jump threading code. */
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calculate_dominance_info (CDI_DOMINATORS);
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/* We do not allow VRP information to be used for jump threading
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across a back edge in the CFG. Otherwise it becomes too
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difficult to avoid eliminating loop exit tests. Of course
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EDGE_DFS_BACK is not accurate at this time so we have to
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recompute it. */
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mark_dfs_back_edges ();
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/* Allocate our unwinder stack to unwind any temporary equivalences
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that might be recorded. */
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const_and_copies *equiv_stack = new const_and_copies ();
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hash_table<expr_elt_hasher> *avail_exprs
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= new hash_table<expr_elt_hasher> (1024);
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avail_exprs_stack *avail_exprs_stack
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= new class avail_exprs_stack (avail_exprs);
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vrp_jump_threader walker (CDI_DOMINATORS, equiv_stack, avail_exprs_stack);
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walker.vr_values = vr_values;
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walker.walk (fun->cfg->x_entry_block_ptr);
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/* We do not actually update the CFG or SSA graphs at this point as
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ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
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handle ASSERT_EXPRs gracefully. */
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delete equiv_stack;
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delete avail_exprs;
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delete avail_exprs_stack;
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}
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/* STMT is a conditional at the end of a basic block.
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If the conditional is of the form SSA_NAME op constant and the SSA_NAME
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@ -4516,7 +4515,8 @@ execute_vrp (struct function *fun, bool warn_array_bounds_p)
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/* We must identify jump threading opportunities before we release
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the datastructures built by VRP. */
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identify_jump_threads (fun, &vrp_prop.vr_values);
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vrp_jump_threader threader (fun, &vrp_prop.vr_values);
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threader.thread_jumps ();
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/* A comparison of an SSA_NAME against a constant where the SSA_NAME
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was set by a type conversion can often be rewritten to use the
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