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tree-optimization/109046 - re-combine complex loads

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The following addresses PR109046 by adding an optimization to forwprop
to combine a piecewise complex load to a complex load when there are
no other uses of the components.  That's something useful in general and
easier to do than avoiding the splitting in complex lowering.

The testcase exercises both the manual and the complex lowering case.

	PR tree-optimization/109046
	* tree-ssa-forwprop.cc (pass_forwprop::execute): Combine
	piecewise complex loads.

	* gcc.dg/tree-ssa/forwprop-39.c: New testcase.
This commit is contained in:
Richard Biener 2023-03-07 11:04:55 +01:00
parent 44ea73185a
commit eb337d28c3
2 changed files with 47 additions and 1 deletions
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15
gcc/testsuite/gcc.dg/tree-ssa/forwprop-39.c Normal file
View file

@ -0,0 +1,15 @@
/* { dg-do compile } */
/* { dg-options "-std=c11 -O2 -fdump-tree-forwprop1 -fdump-tree-optimized" } */
#include <complex.h>
extern void push1(void *p, float _Complex x);
void foo (void *q, float _Complex *x)
{
float r = __real *x;
float i = __imag *x;
push1 (q, CMPLXF (r, i));
}
/* { dg-final { scan-tree-dump-not "COMPLEX_EXPR" "forwprop1" } } */
/* { dg-final { scan-tree-dump-not "REALPART_EXPR" "optimized" } } */

33
gcc/tree-ssa-forwprop.cc
View file

@ -3669,7 +3669,8 @@ pass_forwprop::execute (function *fun)
/* Rewrite stores of a single-use complex build expression
to component-wise stores. */
use_operand_p use_p;
gimple *use_stmt;
gimple *use_stmt, *def1, *def2;
tree rhs2;
if (single_imm_use (lhs, &use_p, &use_stmt)
&& gimple_store_p (use_stmt)
&& !gimple_has_volatile_ops (use_stmt)
@ -3703,6 +3704,36 @@ pass_forwprop::execute (function *fun)
release_defs (stmt);
gsi_remove (&gsi, true);
}
/* Rewrite a component-wise load of a complex to a complex
load if the components are not used separately. */
else if (TREE_CODE (rhs) == SSA_NAME
&& has_single_use (rhs)
&& ((rhs2 = gimple_assign_rhs2 (stmt)), true)
&& TREE_CODE (rhs2) == SSA_NAME
&& has_single_use (rhs2)
&& (def1 = SSA_NAME_DEF_STMT (rhs),
gimple_assign_load_p (def1))
&& (def2 = SSA_NAME_DEF_STMT (rhs2),
gimple_assign_load_p (def2))
&& (gimple_vuse (def1) == gimple_vuse (def2))
&& !gimple_has_volatile_ops (def1)
&& !gimple_has_volatile_ops (def2)
&& gimple_assign_rhs_code (def1) == REALPART_EXPR
&& gimple_assign_rhs_code (def2) == IMAGPART_EXPR
&& operand_equal_p (TREE_OPERAND (gimple_assign_rhs1
(def1), 0),
TREE_OPERAND (gimple_assign_rhs1
(def2), 0)))
{
tree cl = TREE_OPERAND (gimple_assign_rhs1 (def1), 0);
gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (cl));
gcc_assert (gsi_stmt (gsi) == stmt);
gimple_set_vuse (stmt, gimple_vuse (def1));
gimple_set_modified (stmt, true);
gimple_stmt_iterator gsi2 = gsi_for_stmt (def1);
gsi_remove (&gsi, false);
gsi_insert_after (&gsi2, stmt, GSI_SAME_STMT);
}
else
gsi_next (&gsi);
}