I noticed we don't handle secondary effects of restrict in FRE when
looking at another testcase from PR48885:
int
f (int *__restrict__ &__restrict__ p, int *p2)
{
*p = 1;
*p2 = 2;
return *p;
}
with the previously posted patch to improve the handling for p2
we should be able to optimize the return stmt to return 1
in FRE1. Without the following patch we remove the redundant
load of 'p' but not the load from *p. This is because the SCCVN
IL didn't record dependence info and did not reconstruct it for
the alias walks or final PRE insert.
The following fixes that - bootstrap and regtest running on
x86_64-unknown-linux-gnu.
Richard.
2015-09-23 Richard Biener <rguent...@suse.de>
* tree-ssa-sccvn.h (vn_reference_op_struct): Add clique and base
members.
* tree-ssa-sccvn.c (copy_reference_ops_from_ref): Record clique
and base for MEM_REF and TARGET_MEM_REF. Handle BIT_FIELD_REF
offset.
(ao_ref_init_from_vn_reference): Record clique and base in the
built base.
* tree-ssa-pre.c (create_component_ref_by_pieces_1): Likewise
* g++.dg/tree-ssa/restrict3.C: New testcase.
Index: gcc/tree-ssa-sccvn.h
===================================================================
*** gcc/tree-ssa-sccvn.h (revision 228037)
--- gcc/tree-ssa-sccvn.h (working copy)
*************** typedef struct vn_reference_op_struct
*** 83,88 ****
--- 83,91 ----
ENUM_BITFIELD(tree_code) opcode : 16;
/* 1 for instrumented calls. */
unsigned with_bounds : 1;
+ /* Dependence info, used for [TARGET_]MEM_REF only. */
+ unsigned short clique;
+ unsigned short base;
/* Constant offset this op adds or -1 if it is variable. */
HOST_WIDE_INT off;
tree type;
Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c (revision 228037)
--- gcc/tree-ssa-sccvn.c (working copy)
*************** copy_reference_ops_from_ref (tree ref, v
*** 773,778 ****
--- 783,790 ----
temp.op1 = TMR_STEP (ref);
temp.op2 = TMR_OFFSET (ref);
temp.off = -1;
+ temp.clique = MR_DEPENDENCE_CLIQUE (ref);
+ temp.base = MR_DEPENDENCE_BASE (ref);
result->quick_push (temp);
memset (&temp, 0, sizeof (temp));
*************** copy_reference_ops_from_ref (tree ref, v
*** 816,826 ****
--- 828,846 ----
temp.op0 = TREE_OPERAND (ref, 1);
if (tree_fits_shwi_p (TREE_OPERAND (ref, 1)))
temp.off = tree_to_shwi (TREE_OPERAND (ref, 1));
+ temp.clique = MR_DEPENDENCE_CLIQUE (ref);
+ temp.base = MR_DEPENDENCE_BASE (ref);
break;
case BIT_FIELD_REF:
/* Record bits and position. */
temp.op0 = TREE_OPERAND (ref, 1);
temp.op1 = TREE_OPERAND (ref, 2);
+ if (tree_fits_shwi_p (TREE_OPERAND (ref, 2)))
+ {
+ HOST_WIDE_INT off = tree_to_shwi (TREE_OPERAND (ref, 2));
+ if (off % BITS_PER_UNIT == 0)
+ temp.off = off / 8;
+ }
break;
case COMPONENT_REF:
/* The field decl is enough to unambiguously specify the field,
*************** ao_ref_init_from_vn_reference (ao_ref *r
*** 1017,1022 ****
--- 1037,1044 ----
base_alias_set = get_deref_alias_set (op->op0);
*op0_p = build2 (MEM_REF, op->type,
NULL_TREE, op->op0);
+ MR_DEPENDENCE_CLIQUE (*op0_p) = op->clique;
+ MR_DEPENDENCE_BASE (*op0_p) = op->base;
op0_p = &TREE_OPERAND (*op0_p, 0);
break;
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c (revision 228037)
--- gcc/tree-ssa-pre.c (working copy)
*************** create_component_ref_by_pieces_1 (basic_
*** 2531,2537 ****
off));
baseop = build_fold_addr_expr (base);
}
! return fold_build2 (MEM_REF, currop->type, baseop, offset);
}
case TARGET_MEM_REF:
--- 2531,2540 ----
off));
baseop = build_fold_addr_expr (base);
}
! genop = build2 (MEM_REF, currop->type, baseop, offset);
! MR_DEPENDENCE_CLIQUE (genop) = currop->clique;
! MR_DEPENDENCE_BASE (genop) = currop->base;
! return genop;
}
case TARGET_MEM_REF:
*************** create_component_ref_by_pieces_1 (basic_
*** 2554,2561 ****
if (!genop1)
return NULL_TREE;
}
! return build5 (TARGET_MEM_REF, currop->type,
! baseop, currop->op2, genop0, currop->op1, genop1);
}
case ADDR_EXPR:
--- 2557,2568 ----
if (!genop1)
return NULL_TREE;
}
! genop = build5 (TARGET_MEM_REF, currop->type,
! baseop, currop->op2, genop0, currop->op1, genop1);
!
! MR_DEPENDENCE_CLIQUE (genop) = currop->clique;
! MR_DEPENDENCE_BASE (genop) = currop->base;
! return genop;
}
case ADDR_EXPR:
Index: gcc/testsuite/g++.dg/tree-ssa/restrict3.C
===================================================================
*** gcc/testsuite/g++.dg/tree-ssa/restrict3.C (revision 0)
--- gcc/testsuite/g++.dg/tree-ssa/restrict3.C (working copy)
***************
*** 0 ****
--- 1,12 ----
+ // { dg-do compile }
+ // { dg-options "-O -fdump-tree-fre1" }
+
+ int
+ f (int *__restrict__ &__restrict__ p, int *p2)
+ {
+ *p = 1;
+ *p2 = 2;
+ return *p;
+ }
+
+ // { dg-final { scan-tree-dump "return 1;" "fre1" } }
