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Optimize for superfluous cases of NOT, i.e !!!!x can be simplified to !!x.

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This commit is contained in:
Dale Weiler 2013-09-28 05:34:53 -04:00
parent 0d1f20fea3
commit 2b3663e18d
2 changed files with 37 additions and 1 deletions
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8
gmqcc.h
View file

@ -726,7 +726,13 @@ enum {
VINSTR_BITXOR,
VINSTR_BITXOR_V,
VINSTR_BITXOR_VF,
VINSTR_CROSS
VINSTR_CROSS,
/*
* An instruction that is never emitted, useful for marking ir_instr
* to not be generated (just set the ->opcode member to it).
*/
VINSTR_NOP
};
/* TODO: elide */

30
ir.c
View file

@ -2799,6 +2799,10 @@ static bool gen_blocks_recursive(code_t *code, ir_function *func, ir_block *bloc
{
instr = block->instr[i];
/* Ignore NOP instruction */
if (instr->opcode == VINSTR_NOP)
continue;
if (instr->opcode == VINSTR_PHI) {
irerror(block->context, "cannot generate virtual instruction (phi)");
return false;
@ -3174,6 +3178,32 @@ static bool gen_blocks_recursive(code_t *code, ir_function *func, ir_block *bloc
if (instr->_ops[2])
stmt.o2.u1 = ir_value_code_addr(instr->_ops[2]);
if (stmt.opcode == INSTR_NOT_F) {
/*
* We can optimize for superfluous cases of not. Consider
*/
if (i + 4 <= vec_size(block->instr)) {
for (j = 0; j < 2; j++) {
if (ir_value_code_addr(block->instr[i+j]->_ops[0]) != ir_value_code_addr(block->instr[i+j]->_ops[1]))
break;
}
if (--j && block->instr[i+2]->_ops[0] && block->instr[i+2]->_ops[1]
&& block->instr[i+3]->_ops[0] && block->instr[i+2]->_ops[1]
&& ir_value_code_addr(block->instr[i+2]->_ops[1]) == ir_value_code_addr(block->instr[i+3]->_ops[0])
&& ir_value_code_addr(block->instr[i+2]->_ops[0]) == ir_value_code_addr(block->instr[i+3]->_ops[1]))
{
code_push_statement(code, &stmt, instr->context);
code_push_statement(code, &stmt, instr->context);
for (j = 1; j < 4; j++)
block->instr[i+j]->opcode = VINSTR_NOP;
++opts_optimizationcount[OPTIM_PEEPHOLE];
continue;
}
}
code_push_statement(code, &stmt, instr->context);
continue;
}
if (stmt.opcode == INSTR_RETURN || stmt.opcode == INSTR_DONE)
{
stmt.o1.u1 = stmt.o3.u1;