From b673e7547fb95d1f0d5cd17ae9e3874742cade66 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 16 Jan 2021 09:17:38 +0100 Subject: [PATCH] cd_dce: Return TODO_update_address_taken from last cd_dce [PR96271] On the following testcase, handle_builtin_memcmp in the strlen pass folds the memcmp into comparison of two MEM_REFs. But nothing triggers updating of addressable vars afterwards, so even when the parameters are no longer address taken, we force the parameters to stack and back anyway. This patch causes TODO_update_address_taken to happen right before last forwprop pass (at the end of last cd_dce), so after strlen1 too. 2021-01-16 Jakub Jelinek PR tree-optimization/96271 * passes.def: Pass false argument to first two pass_cd_dce instances and true to last instance. Add comment that last instance rewrites no longer addressed locals. * tree-ssa-dce.c (pass_cd_dce): Add update_address_taken_p member and initialize it. (pass_cd_dce::set_pass_param): New method. (pass_cd_dce::execute): Return TODO_update_address_taken from last cd_dce instance. * gcc.target/i386/pr96271.c: New test. --- gcc/passes.def | 8 +++++--- gcc/testsuite/gcc.target/i386/pr96271.c | 11 +++++++++++ gcc/tree-ssa-dce.c | 15 +++++++++++++-- 3 files changed, 29 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr96271.c diff --git a/gcc/passes.def b/gcc/passes.def index c8e01ae055d..e9ed3c7bc57 100644 --- a/gcc/passes.def +++ b/gcc/passes.def @@ -90,7 +90,7 @@ along with GCC; see the file COPYING3. If not see NEXT_PASS (pass_early_vrp); NEXT_PASS (pass_merge_phi); NEXT_PASS (pass_dse); - NEXT_PASS (pass_cd_dce); + NEXT_PASS (pass_cd_dce, false /* update_address_taken_p */); NEXT_PASS (pass_phiopt, true /* early_p */); NEXT_PASS (pass_modref); NEXT_PASS (pass_tail_recursion); @@ -272,7 +272,7 @@ along with GCC; see the file COPYING3. If not see NEXT_PASS (pass_loop_jam); /* All unswitching, final value replacement and splitting can expose empty loops. Remove them now. */ - NEXT_PASS (pass_cd_dce); + NEXT_PASS (pass_cd_dce, false /* update_address_taken_p */); NEXT_PASS (pass_iv_canon); NEXT_PASS (pass_loop_distribution); NEXT_PASS (pass_linterchange); @@ -336,7 +336,9 @@ along with GCC; see the file COPYING3. If not see NEXT_PASS (pass_copy_prop); NEXT_PASS (pass_warn_restrict); NEXT_PASS (pass_dse); - NEXT_PASS (pass_cd_dce); + NEXT_PASS (pass_cd_dce, true /* update_address_taken_p */); + /* After late CD DCE we rewrite no longer addressed locals into SSA + form if possible. */ NEXT_PASS (pass_forwprop); NEXT_PASS (pass_phiopt, false /* early_p */); NEXT_PASS (pass_fold_builtins); diff --git a/gcc/testsuite/gcc.target/i386/pr96271.c b/gcc/testsuite/gcc.target/i386/pr96271.c new file mode 100644 index 00000000000..b916bd1e0a1 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr96271.c @@ -0,0 +1,11 @@ +/* PR tree-optimization/96271 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -mtune=intel -msse2 -masm=att" } */ +/* { dg-final { scan-assembler "movq\t%xmm0, %r" { target { ! ia32 } } } } */ +/* { dg-final { scan-assembler "movq\t%xmm1, %r" { target { ! ia32 } } } } */ + +int +foo (double a, double b) +{ + return __builtin_memcmp (&a, &b, sizeof (double)) == 0; +} diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c index 51d4fcbb1c8..c027230acdc 100644 --- a/gcc/tree-ssa-dce.c +++ b/gcc/tree-ssa-dce.c @@ -1787,14 +1787,25 @@ class pass_cd_dce : public gimple_opt_pass { public: pass_cd_dce (gcc::context *ctxt) - : gimple_opt_pass (pass_data_cd_dce, ctxt) + : gimple_opt_pass (pass_data_cd_dce, ctxt), update_address_taken_p (false) {} /* opt_pass methods: */ opt_pass * clone () { return new pass_cd_dce (m_ctxt); } + void set_pass_param (unsigned n, bool param) + { + gcc_assert (n == 0); + update_address_taken_p = param; + } virtual bool gate (function *) { return flag_tree_dce != 0; } - virtual unsigned int execute (function *) { return tree_ssa_cd_dce (); } + virtual unsigned int execute (function *) + { + return (tree_ssa_cd_dce () + | (update_address_taken_p ? TODO_update_address_taken : 0)); + } +private: + bool update_address_taken_p; }; // class pass_cd_dce } // anon namespace