From 113d06a486475c8c1682771a392fdb056685cf01 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Fri, 23 Sep 2016 12:39:05 +0000 Subject: [PATCH] tree-ssa-sccvn.c (visit_reference_op_call): Value number virtual definition to virtual use if... 2016-09-23 Richard Biener * tree-ssa-sccvn.c (visit_reference_op_call): Value number virtual definition to virtual use if the call devirtualizes to a const or pure function. (visit_use): Also visit calls we can devirtualize to a const or pure function. * gcc.dg/tree-ssa/ssa-fre-56.c: New testcase. From-SVN: r240431 --- gcc/ChangeLog | 8 ++++++ gcc/testsuite/ChangeLog | 4 +++ gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-56.c | 26 +++++++++++++++++ gcc/tree-ssa-sccvn.c | 33 ++++++++++++++++++++-- 4 files changed, 68 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-56.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 2c4cf4328c2..914624d3f82 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2016-09-23 Richard Biener + + * tree-ssa-sccvn.c (visit_reference_op_call): Value number + virtual definition to virtual use if the call devirtualizes + to a const or pure function. + (visit_use): Also visit calls we can devirtualize to a + const or pure function. + 2016-09-23 Richard Biener PR tree-optimization/77697 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 8305520fbdd..7a87fea6a71 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2016-09-23 Richard Biener + + * gcc.dg/tree-ssa/ssa-fre-56.c: New testcase. + 2016-09-23 Matthew Wahab * gcc.target/advsimd-intrinsics/advsimd-intrinsics.exp: Enable diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-56.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-56.c new file mode 100644 index 00000000000..49c6fa1d6b3 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-56.c @@ -0,0 +1,26 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-fre1" } */ + +int x = 1; +int __attribute__((noinline,noclone)) fn () +{ + return x; +} +int (*f)(); +int main () +{ + int res; + f = fn; + x = 0; + res = f (); + res += x; + if (res != 0) + __builtin_abort (); + return 0; +} + +/* We should be able to optimize the load from x in main and thus the + addition. */ + +/* { dg-final { scan-tree-dump-times "= x;" 1 "fre1" } } */ +/* { dg-final { scan-tree-dump-times " \\\+ " 0 "fre1" } } */ diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 21cc54e60b6..7f44ec8a241 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -3484,8 +3484,24 @@ visit_reference_op_call (tree lhs, gcall *stmt) { vn_reference_t vr2; vn_reference_s **slot; + tree vdef_val = vdef; if (vdef) - changed |= set_ssa_val_to (vdef, vdef); + { + /* If we value numbered an indirect functions function to + one not clobbering memory value number its VDEF to its + VUSE. */ + tree fn = gimple_call_fn (stmt); + if (fn && TREE_CODE (fn) == SSA_NAME) + { + fn = SSA_VAL (fn); + if (TREE_CODE (fn) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL + && (flags_from_decl_or_type (TREE_OPERAND (fn, 0)) + & (ECF_CONST | ECF_PURE))) + vdef_val = vuse_ssa_val (gimple_vuse (stmt)); + } + changed |= set_ssa_val_to (vdef, vdef_val); + } if (lhs) changed |= set_ssa_val_to (lhs, lhs); vr2 = current_info->references_pool->allocate (); @@ -3498,7 +3514,7 @@ visit_reference_op_call (tree lhs, gcall *stmt) vr2->set = vr1.set; vr2->hashcode = vr1.hashcode; vr2->result = lhs; - vr2->result_vdef = vdef; + vr2->result_vdef = vdef_val; slot = current_info->references->find_slot_with_hash (vr2, vr2->hashcode, INSERT); gcc_assert (!*slot); @@ -3912,11 +3928,22 @@ visit_use (tree use) } } + /* Pick up flags from a devirtualization target. */ + tree fn = gimple_call_fn (stmt); + int extra_fnflags = 0; + if (fn && TREE_CODE (fn) == SSA_NAME) + { + fn = SSA_VAL (fn); + if (TREE_CODE (fn) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL) + extra_fnflags = flags_from_decl_or_type (TREE_OPERAND (fn, 0)); + } if (!gimple_call_internal_p (call_stmt) && (/* Calls to the same function with the same vuse and the same operands do not necessarily return the same value, unless they're pure or const. */ - gimple_call_flags (call_stmt) & (ECF_PURE | ECF_CONST) + ((gimple_call_flags (call_stmt) | extra_fnflags) + & (ECF_PURE | ECF_CONST)) /* If calls have a vdef, subsequent calls won't have the same incoming vuse. So, if 2 calls with vdef have the same vuse, we know they're not subsequent. -- 2.30.2