144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
#include "mcg.h"
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static PMAPOF(struct basicblock, struct basicblock) graph;
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static ARRAYOF(struct ir) pops;
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static ARRAYOF(struct ir) pushes;
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static struct ir* get_last_push(struct basicblock* bb)
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{
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int i;
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for (i=bb->irs.count-1; i>=0; i--)
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{
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struct ir* ir = bb->irs.item[i];
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if (ir->opcode == IR_PUSH)
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return ir;
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if (ir_find(ir, IR_POP))
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return NULL;
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}
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return NULL;
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}
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static struct ir* get_first_pop(struct basicblock* bb)
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{
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int i;
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for (i=0; i<bb->irs.count; i++)
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{
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struct ir* irr;
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struct ir* ir = bb->irs.item[i];
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if (ir->opcode == IR_PUSH)
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return NULL;
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irr = ir_find(ir, IR_POP);
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if (irr)
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return irr;
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}
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return NULL;
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}
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static bool collect_outputs_cb(struct ir* ir, void* user)
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{
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struct basicblock* caller = user;
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if (ir->opcode == IR_BLOCK)
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pmap_add(&graph, caller, ir->u.bvalue);
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return false;
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}
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static void make_bb_graph(struct procedure* proc)
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{
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int i, j;
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graph.count = 0;
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for (i=0; i<proc->blocks.count; i++)
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{
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struct basicblock* bb = proc->blocks.item[i];
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for (j=0; j<bb->irs.count; j++)
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ir_walk(bb->irs.item[j], collect_outputs_cb, bb);
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}
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}
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static void convert_block(struct procedure* proc, struct basicblock* bb)
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{
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int i, j;
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struct ir* ir;
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pushes.count = pops.count = 0;
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for (;;)
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{
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struct ir* lastpush = get_last_push(bb);
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if (!lastpush)
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return;
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/* Abort unless *every* successor block of this one starts with a pop
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* of the same size... */
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for (i=0; i<graph.count; i++)
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{
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if (graph.item[i].left == bb)
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{
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struct basicblock* outbb = graph.item[i].right;
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ir = get_first_pop(outbb);
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if (!ir || (ir->size != lastpush->size))
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return;
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array_appendu(&pops, ir);
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/* Also abort unless *every* predecessor block of the one we've
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* just found *also* ends in a push of the same size. */
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for (j=0; j<graph.count; j++)
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{
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if (graph.item[j].right == outbb)
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{
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struct basicblock* inbb = graph.item[j].left;
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ir = get_last_push(inbb);
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if (!ir || (ir->size != lastpush->size))
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return;
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array_appendu(&pushes, ir);
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}
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}
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}
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}
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/* Okay, now we can wire them all up. */
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for (i=0; i<pushes.count; i++)
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{
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struct ir* ir = pushes.item[i];
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*ir = *ir->left;
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}
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for (i=0; i<pops.count; i++)
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{
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struct ir* ir = pops.item[i];
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struct ir* phi = new_ir0(IR_PHI, ir->size);
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for (j=0; j<pushes.count; j++)
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array_appendu(&phi->u.phivalue, pushes.item[j]);
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phi->root = phi;
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*ir = *phi;
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array_insert(&bb->irs, ir, 0);
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}
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}
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}
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void pass_convert_stack_ops(struct procedure* proc)
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{
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int i;
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make_bb_graph(proc);
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for (i=0; i<proc->blocks.count; i++)
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convert_block(proc, proc->blocks.item[i]);
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}
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/* vim: set sw=4 ts=4 expandtab : */
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