From 529f304811542ca34030b0dc0a7621503998da66 Mon Sep 17 00:00:00 2001 From: Matthew Beliveau Date: Tue, 20 Aug 2019 13:23:01 +0000 Subject: [PATCH] tree-ssa-dse.c (dse_optimize_redundant_stores): Improved check to catch more redundant zero initialization cases. 2019-08-19 Matthew Beliveau * tree-ssa-dse.c (dse_optimize_redundant_stores): Improved check to catch more redundant zero initialization cases. (dse_dom_walker::dse_optimize_stmt): Likewise. From-SVN: r274749 --- gcc/ChangeLog | 6 +++++ gcc/testsuite/ChangeLog | 5 +++++ .../gcc.dg/tree-ssa/redundant-assign-zero-1.c | 13 +++++++++++ .../gcc.dg/tree-ssa/redundant-assign-zero-2.c | 18 +++++++++++++++ gcc/tree-ssa-dse.c | 22 ++++++------------- 5 files changed, 49 insertions(+), 15 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-1.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-2.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 353429d0f17..ecb7c06507c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2019-08-20 Matthew Beliveau + + * tree-ssa-dse.c (dse_optimize_redundant_stores): Improved check to + catch more redundant zero initialization cases. + (dse_dom_walker::dse_optimize_stmt): Likewise. + 2019-08-20 Richard Biener PR lto/91307 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 5316e07a434..0512a60019d 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2019-08-20 Matthew Beliveau + + * gcc.dg/tree-ssa/redundant-assign-zero-1.c: New test. + * gcc.dg/tree-ssa/redundant-assign-zero-2.c: New test. + 2019-08-20 Richard Biener PR tree-optimization/37242 diff --git a/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-1.c b/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-1.c new file mode 100644 index 00000000000..b8d01d1644b --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-1.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-dse-details" } */ + +void blah (char *); + +void bar () +{ + char a[256] = ""; + a[3] = 0; + blah (a); +} + +/* { dg-final { scan-tree-dump-times "Deleted redundant store" 1 "dse1"} } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-2.c b/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-2.c new file mode 100644 index 00000000000..8cefa6f0cb7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-2.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-dse-details" } */ + +#include + +void blahd (double *); + +void fubar () +{ + double d; + double *x = &d; + + memset (&d, 0 , sizeof d); + *x = 0.0; + blahd (x); +} + +/* { dg-final { scan-tree-dump-times "Deleted redundant store" 1 "dse1"} } */ diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 5b7c4fc6d1a..ba67884a825 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -628,11 +628,8 @@ dse_optimize_redundant_stores (gimple *stmt) tree fndecl; if ((is_gimple_assign (use_stmt) && gimple_vdef (use_stmt) - && ((gimple_assign_rhs_code (use_stmt) == CONSTRUCTOR - && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (use_stmt)) == 0 - && !gimple_clobber_p (stmt)) - || (gimple_assign_rhs_code (use_stmt) == INTEGER_CST - && integer_zerop (gimple_assign_rhs1 (use_stmt))))) + && (gimple_assign_single_p (use_stmt) + && initializer_zerop (gimple_assign_rhs1 (use_stmt)))) || (gimple_call_builtin_p (use_stmt, BUILT_IN_NORMAL) && (fndecl = gimple_call_fndecl (use_stmt)) != NULL && (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMSET @@ -1027,16 +1024,11 @@ dse_dom_walker::dse_optimize_stmt (gimple_stmt_iterator *gsi) { bool by_clobber_p = false; - /* First see if this store is a CONSTRUCTOR and if there - are subsequent CONSTRUCTOR stores which are totally - subsumed by this statement. If so remove the subsequent - CONSTRUCTOR store. - - This will tend to make fewer calls into memset with longer - arguments. */ - if (gimple_assign_rhs_code (stmt) == CONSTRUCTOR - && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt)) == 0 - && !gimple_clobber_p (stmt)) + /* Check if this statement stores zero to a memory location, + and if there is a subsequent store of zero to the same + memory location. If so, remove the subsequent store. */ + if (gimple_assign_single_p (stmt) + && initializer_zerop (gimple_assign_rhs1 (stmt))) dse_optimize_redundant_stores (stmt); /* Self-assignments are zombies. */ -- 2.30.2