[debug] Reuse debug exprs generated in remap_ssa_name

When compiling gcc.dg/vla-1.c with -O3 -g, vla a and b in f1 are optimized
away, and f1 is cloned to a version f1.constprop with no parameters, eliminating
parameter i.  Debug info is generated to describe the sizes of a and b, but
that process generates debug expressions that are not reused.

Fix the duplication by saving and reusing the generated debug expressions in
remap_ssa_name.  Concretely: reuse D#7 here instead of generating D#8:
...
 __attribute__((noinline))
 f1.constprop ()
 {
   intD.6 iD.1935;

   <bb 3>
   # DEBUG D#10 s=> iD.1897
   # DEBUG iD.1935 => D#10

   <bb 2>
-  # DEBUG D#8 s=> iD.1935
   # DEBUG D#7 s=> iD.1935
   saved_stack.2_1 = __builtin_stack_save ();
   # DEBUG BEGIN_STMT
   # DEBUG D#6 => D#7 + 1
   # DEBUG D#5 => (long intD.8) D#6
   # DEBUG D#4 => D#5 + -1
   # DEBUG D.1937 => (sizetype) D#4
   # DEBUG a.0D.1942 => NULL
   # DEBUG BEGIN_STMT
-  # DEBUG D#3 => D#8 + 2
+  # DEBUG D#3 => D#7 + 2
   # DEBUG D#2 => (long intD.8) D#3
   # DEBUG D#1 => D#2 + -1
   # DEBUG D.1944 => (sizetype) D#1
   # DEBUG b.1D.1949 => NULL
...

Bootstrapped and reg-tested on x86_64.

2018-07-13  Tom de Vries  <tdevries@suse.de>

	* tree-inline.c (remap_ssa_name): Save and reuse debug exprs generated
	in remap_ssa_name.

	* gcc.dg/vla-1.c: Update.

From-SVN: r262628

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b97ebca58c735f748584141e560e13c1f3b930b6..3f70e46d19333fcd0a833953fb08453e9ee70bb8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-07-13  Tom de Vries  <tdevries@suse.de>
+
+       * tree-inline.c (remap_ssa_name): Save and reuse debug exprs generated
+       in remap_ssa_name.
+
 2018-07-13  Jackson Woodruff  <jackson.woodruff@arm.com>
 
        * config/aarch64/aarch64.c (aarch64_operands_adjust_ok_for_ldpstp): Use

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fd47f3d4c271dc3a72aec0125ded068452173007..49ca6c527dd51d4eb1daa8b295a42f3de56f56ad 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2018-07-13  Tom de Vries  <tdevries@suse.de>
+
+       * gcc.dg/vla-1.c: Update.
+
 2018-07-13  Tom de Vries  <tdevries@suse.de>
 
        * gcc.src/maintainers.exp: New file.

diff --git a/gcc/testsuite/gcc.dg/vla-1.c b/gcc/testsuite/gcc.dg/vla-1.c
index 56437ae44deb7cee27160a6bc404c6952c32e0ea..902166cb18c964ad9d52e95aa68e2447b3deb668 100644 (file)
--- a/gcc/testsuite/gcc.dg/vla-1.c
+++ b/gcc/testsuite/gcc.dg/vla-1.c
@@ -20,6 +20,7 @@ main ()
   return 0;
 }
 
-/* One debug source bind is generated for the parameter, and two to describe the
+/* One debug source bind is generated for the parameter, and one to describe the
    sizes of a and b.  */
-/* { dg-final { scan-tree-dump-times " s=> i" 3 "optimized" } } */
+/* { dg-final { scan-tree-dump-times " s=> i" 2 "optimized" } } */
+

diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 45aba8171a638cb58f2f454364c61f4782116274..6a16ce546cb04d5a858def36612cc1028a5a22c2 100644 (file)
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -214,12 +214,16 @@ remap_ssa_name (tree name, copy_body_data *id)
              processing_debug_stmt = -1;
              return name;
            }
+         n = id->decl_map->get (val);
+         if (n && TREE_CODE (*n) == DEBUG_EXPR_DECL)
+           return *n;
          def_temp = gimple_build_debug_source_bind (vexpr, val, NULL);
          DECL_ARTIFICIAL (vexpr) = 1;
          TREE_TYPE (vexpr) = TREE_TYPE (name);
          SET_DECL_MODE (vexpr, DECL_MODE (SSA_NAME_VAR (name)));
          gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
          gsi_insert_before (&gsi, def_temp, GSI_SAME_STMT);
+         insert_decl_map (id, val, vexpr);
          return vexpr;
        }