Hi!
During analysis, we correctly ignore debug stmt uses, but if we don't
release the ssa name we stopped using, the debug stmts uses are left in the
IL. The reset_debug_uses call is needed because the code modifies the
division stmt in place. Perhaps better would be not to do that, i.e.
create a new division and gsi_replace it, then just the release_ssa_name
would be enough and the generic code could add e.g. the 1.0 / _1 replacement
for the debug stmt? Though, in this particular case the sqrt call is
optimized away, so it wouldn't make a difference.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk, or
should I do the gimple_build_assign + gsi_replace change?
2018-11-13 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/87977
* tree-ssa-math-opts.c (optimize_recip_sqrt): Call reset_debug_uses
on stmt before changing the lhs if !has_other_use. Formatting fix.
Call release_ssa_name (x) if !has_other_use and !delete_div.
* gcc.dg/recip_sqrt_mult_1.c: Add -fcompare-debug to dg-options.
* gcc.dg/recip_sqrt_mult_2.c: Likewise.
* gcc.dg/recip_sqrt_mult_3.c: Likewise.
* gcc.dg/recip_sqrt_mult_4.c: Likewise.
* gcc.dg/recip_sqrt_mult_5.c: Likewise.
--- gcc/tree-ssa-math-opts.c.jj 2018-10-23 10:13:22.640922226 +0200
+++ gcc/tree-ssa-math-opts.c 2018-11-12 16:55:45.468734060 +0100
@@ -652,6 +652,8 @@ optimize_recip_sqrt (gimple_stmt_iterato
print_gimple_stmt (dump_file, stmt, 0, TDF_NONE);
fprintf (dump_file, "with new division\n");
}
+ if (!has_other_use)
+ reset_debug_uses (stmt);
gimple_assign_set_lhs (stmt, sqr_ssa_name);
gimple_assign_set_rhs2 (stmt, a);
fold_stmt_inplace (def_gsi);
@@ -704,7 +706,7 @@ optimize_recip_sqrt (gimple_stmt_iterato
gimple *new_stmt
= gimple_build_assign (x, MULT_EXPR,
- orig_sqrt_ssa_name, sqr_ssa_name);
+ orig_sqrt_ssa_name, sqr_ssa_name);
gsi_insert_after (def_gsi, new_stmt, GSI_NEW_STMT);
update_stmt (stmt);
}
@@ -715,6 +717,8 @@ optimize_recip_sqrt (gimple_stmt_iterato
gsi_remove (&gsi2, true);
release_defs (stmt);
}
+ else
+ release_ssa_name (x);
}
/* Look for floating-point divisions among DEF's uses, and try to
--- gcc/testsuite/gcc.dg/recip_sqrt_mult_1.c.jj 2018-09-11 18:12:24.876207127
+0200
+++ gcc/testsuite/gcc.dg/recip_sqrt_mult_1.c 2018-11-12 16:57:53.301634244
+0100
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-Ofast -fdump-tree-recip" } */
+/* { dg-options "-Ofast -fdump-tree-recip -fcompare-debug" } */
double res, res2, tmp;
void
--- gcc/testsuite/gcc.dg/recip_sqrt_mult_2.c.jj 2018-09-11 18:12:24.876207127
+0200
+++ gcc/testsuite/gcc.dg/recip_sqrt_mult_2.c 2018-11-12 16:58:01.250503686
+0100
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-Ofast -fdump-tree-optimized" } */
+/* { dg-options "-Ofast -fdump-tree-optimized -fcompare-debug" } */
float
foo (float a)
--- gcc/testsuite/gcc.dg/recip_sqrt_mult_3.c.jj 2018-09-11 18:12:24.876207127
+0200
+++ gcc/testsuite/gcc.dg/recip_sqrt_mult_3.c 2018-11-12 16:58:12.302322133
+0100
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-Ofast -fdump-tree-optimized" } */
+/* { dg-options "-Ofast -fdump-tree-optimized -fcompare-debug" } */
double
foo (double a)
--- gcc/testsuite/gcc.dg/recip_sqrt_mult_4.c.jj 2018-09-11 18:12:24.877207110
+0200
+++ gcc/testsuite/gcc.dg/recip_sqrt_mult_4.c 2018-11-12 16:58:35.748936997
+0100
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-Ofast -fdump-tree-recip" } */
+/* { dg-options "-Ofast -fdump-tree-recip -fcompare-debug" } */
/* The main path doesn't have any multiplications.
Avoid introducing them in the recip pass. */
--- gcc/testsuite/gcc.dg/recip_sqrt_mult_5.c.jj 2018-09-11 18:12:24.875207143
+0200
+++ gcc/testsuite/gcc.dg/recip_sqrt_mult_5.c 2018-11-12 16:58:41.950835127
+0100
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-Ofast -fdump-tree-recip" } */
+/* { dg-options "-Ofast -fdump-tree-recip -fcompare-debug" } */
/* We want to do the recip_sqrt transformations here there is already
a multiplication on the main path. */
Jakub
