From cc788fcc70a93b25b78cb72f31da3a2159930824 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Mon, 8 Mar 2010 13:30:27 +0000 Subject: [PATCH] re PR tree-optimization/43269 (removing non dead store) 2010-03-08 Richard Guenther PR tree-optimization/43269 * tree-ssa-dse.c (dse_possible_dead_store_p): Fix post-dom region detection. * gcc.c-torture/execute/pr43269.c: New testcase. From-SVN: r157276 --- gcc/ChangeLog | 6 ++++ gcc/testsuite/ChangeLog | 5 +++ gcc/testsuite/gcc.c-torture/execute/pr43269.c | 31 +++++++++++++++++++ gcc/tree-ssa-dse.c | 27 +++++++++------- 4 files changed, 58 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr43269.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index bc6d1e0851f..b84da2f86dc 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2010-03-08 Richard Guenther + + PR tree-optimization/43269 + * tree-ssa-dse.c (dse_possible_dead_store_p): Fix post-dom + region detection. + 2010-03-08 Martin Jambor * ipa-prop.h (struct ipa_param_descriptor): Removed the called field. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index edd3648604c..197d695a84e 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2010-03-08 Richard Guenther + + PR tree-optimization/43269 + * gcc.c-torture/execute/pr43269.c: New testcase. + 2010-03-08 Janus Weil PR fortran/43256 diff --git a/gcc/testsuite/gcc.c-torture/execute/pr43269.c b/gcc/testsuite/gcc.c-torture/execute/pr43269.c new file mode 100644 index 00000000000..9f599a2dd5d --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr43269.c @@ -0,0 +1,31 @@ +int g_21; +int g_211; +int g_261; + +static void __attribute__((noinline,noclone)) +func_32 (int b) +{ + if (b) { +lbl_370: + g_21 = 1; + } + + for (g_261 = -1; g_261 > -2; g_261--) { + if (g_211 + 1) { + return; + } else { + g_21 = 1; + goto lbl_370; + } + } +} + +extern void abort (void); + +int main(void) +{ + func_32(0); + if (g_261 != -1) + abort (); + return 0; +} diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 37a548189a4..b678a8f829f 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -161,7 +161,7 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt) temp = stmt; do { - gimple prev, use_stmt; + gimple use_stmt; imm_use_iterator ui; bool fail = false; tree defvar; @@ -175,28 +175,33 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt) defvar = PHI_RESULT (temp); else defvar = gimple_vdef (temp); - prev = temp; temp = NULL; FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar) { cnt++; + /* If we ever reach our DSE candidate stmt again fail. We + cannot handle dead stores in loops. */ + if (use_stmt == stmt) + { + fail = true; + BREAK_FROM_IMM_USE_STMT (ui); + } /* In simple cases we can look through PHI nodes, but we have to be careful with loops and with memory references containing operands that are also operands of PHI nodes. See gcc.c-torture/execute/20051110-*.c. */ - if (gimple_code (use_stmt) == GIMPLE_PHI) + else if (gimple_code (use_stmt) == GIMPLE_PHI) { if (temp - /* We can look through PHIs to post-dominated regions - without worrying if the use not also dominates prev - (in which case it would be a loop PHI with the use - in a latch block). */ - || gimple_bb (prev) == gimple_bb (use_stmt) - || !dominated_by_p (CDI_POST_DOMINATORS, - gimple_bb (prev), gimple_bb (use_stmt)) + /* Make sure we are not in a loop latch block. */ + || gimple_bb (stmt) == gimple_bb (use_stmt) || dominated_by_p (CDI_DOMINATORS, - gimple_bb (prev), gimple_bb (use_stmt))) + gimple_bb (stmt), gimple_bb (use_stmt)) + /* We can look through PHIs to regions post-dominating + the DSE candidate stmt. */ + || !dominated_by_p (CDI_POST_DOMINATORS, + gimple_bb (stmt), gimple_bb (use_stmt))) { fail = true; BREAK_FROM_IMM_USE_STMT (ui);