Commit 67aaf700 authored by Matthias Braun's avatar Matthias Braun
Browse files

Liebe part3: mux lowerer (with minimal changes)

[r26919]
parent f1b4ef67
......@@ -305,6 +305,26 @@ void ir_lower_mode_b(ir_graph *irg, const lower_mode_b_config_t *config);
ir_graph_pass_t *ir_lower_mode_b_pass(
const char *name, const lower_mode_b_config_t *config);
/**
* Used as callback, whenever a lowerable mux is found. The return value
* indicates, whether the mux should be lowered. This may be used, to lower
* floating point muxes, while keeping mux nodes for integers, for example.
*
* @param mux The mux node that may be lowered.
* @return A non-zero value indicates that the mux should be lowered.
*/
typedef int lower_mux_callback(ir_node* mux);
/**
* Lowers all mux nodes in the given graph. A callback function may be
* given, to select the mux nodes to lower.
*
* @param irg The graph to lower mux nodes in.
* @param cb_func The callback function for mux selection. Can be NULL,
* to lower all mux nodes.
*/
void lower_mux(ir_graph *irg, lower_mux_callback *cb_func);
/**
* An intrinsic mapper function.
*
......
......@@ -192,6 +192,7 @@ libfirm_la_SOURCES = \
lower/lower_hl.c \
lower/lower_intrinsics.c \
lower/lower_mode_b.c \
lower/lower_mux.c \
lower/lower_switch.c \
obstack/obstack.c \
obstack/obstack_printf.c \
......
......@@ -32,7 +32,8 @@
* - The only nodes producing mode_b are: Proj(Cmp) and ConvB(X) (where X
* is some mode that can be converted to the lowered mode).
* ConvB will usually be implemented by a comparison with 0 producing some
* flags in the backends.
* flags in the backends. It's debatable wether ConvB(X) is a goode idea.
* Maybe we should rather introduce a Test node.
* All other former uses should be converted to manipulations with an integer
* mode that was specified in the pass configuration.
*/
......
/*
* Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
*
* This file is part of libFirm.
*
* This file may be distributed and/or modified under the terms of the
* GNU General Public License version 2 as published by the Free Software
* Foundation and appearing in the file LICENSE.GPL included in the
* packaging of this file.
*
* Licensees holding valid libFirm Professional Edition licenses may use
* this file in accordance with the libFirm Commercial License.
* Agreement provided with the Software.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE.
*/
/**
* @file
* @brief Replaces Mux nodes with control-flow
* @author Olaf Liebe
* @version $Id$
*/
#include "config.h"
#include <assert.h>
#include "lowering.h"
#include "array.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irgwalk.h"
#include "irgmod.h"
#include "ircons.h"
#include "irvrfy.h"
typedef struct walk_env {
lower_mux_callback *cb_func;
ir_node **muxes;
} walk_env_t;
static void find_mux_nodes(ir_node *mux, void *ctx)
{
walk_env_t *env = ctx;
/* Skip non-mux nodes. */
if (!is_Mux(mux))
return;
/* Skip nodes, depending on the callback function. */
if (env->cb_func != NULL && !env->cb_func(mux)) {
return;
}
/* Store the node. */
ARR_APP1(ir_node*, env->muxes, mux);
}
static void lower_mux_node(ir_node* mux)
{
ir_node *upper_block;
ir_node *lower_block;
ir_node *cond;
ir_node *trueProj;
ir_node *falseProj;
ir_node *falseBlock;
ir_node *mux_jmps[2];
ir_node *mux_values[2];
ir_node *phi;
ir_node *mbh;
/* Split the block in two halfs, with the mux in the upper block. */
lower_block = get_nodes_block(mux);
assert(lower_block != 0);
part_block(mux);
upper_block = get_cur_block();
/* Create a cond node with two projs and a phi as mux replacement. The
* true proj jumps directly to the lower block, the false proj uses a
* block in-between, so that the phi can be used to select the result
* value from the old mux node in the lower block. */
cond = new_Cond(get_Mux_sel(mux));
trueProj = new_Proj(cond, mode_X, pn_Cond_true);
falseProj = new_Proj(cond, mode_X, pn_Cond_false);
falseBlock = new_Block(1, &falseProj);
mux_jmps[0] = trueProj;
mux_jmps[1] = new_r_Jmp(falseBlock);
/* Kill the jump from upper to lower block and replace the in array. */
assert(get_Block_n_cfgpreds(lower_block) == 1);
kill_node(get_Block_cfgpred(lower_block, 0));
set_irn_in(lower_block, 2, mux_jmps);
/* Combine the two control flows with a phi to select the correct value
* and use it to replace the mux. */
set_cur_block(lower_block);
mux_values[0] = get_Mux_true(mux);
mux_values[1] = get_Mux_false(mux);
phi = new_Phi(2, mux_values, get_irn_mode(mux));
exchange(mux, phi);
/* Add links and update phi node lists, for the next part_block() call.
* lower_block and upper_block have been updated by part_block(). Link
* the projs with the cond, and the new block with the macroblock. */
set_irn_link(trueProj, get_irn_link(cond));
set_irn_link(falseProj, get_irn_link(cond));
set_irn_link(cond, trueProj);
set_irn_link(cond, falseProj);
mbh = get_Block_MacroBlock(falseBlock);
set_irn_link(falseBlock, get_irn_link(mbh));
set_irn_link(mbh, falseBlock);
add_Block_phi(lower_block, phi);
}
void lower_mux(ir_graph *irg, lower_mux_callback *cb_func)
{
int i;
walk_env_t env;
ir_resources_t resources = IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST;
/* Scan the graph for mux nodes to lower. */
env.cb_func = cb_func;
env.muxes = NEW_ARR_F(ir_node*, 0);
irg_walk_graph(irg, find_mux_nodes, 0, &env);
/* This is required by part_block() later. */
ir_reserve_resources(irg, resources);
collect_phiprojs(irg);
for (i = 0; i < ARR_LEN(env.muxes); i++) {
lower_mux_node(env.muxes[i]);
}
/* Cleanup, verify the graph. */
ir_free_resources(irg, resources);
set_irg_outs_inconsistent(irg);
set_irg_doms_inconsistent(irg);
set_irg_extblk_inconsistent(irg);
set_irg_loopinfo_inconsistent(irg);
}
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