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[PATCH][debug] Handle debug references to skipped params
On Fri, Jul 06, 2018 at 04:38:50PM +0200, Richard Biener wrote:
> On Fri, Jul 6, 2018 at 12:47 PM Tom de Vries <tdevries@suse.de> wrote:
> > On 07/05/2018 01:39 PM, Richard Biener wrote:
<SNIP>
> I now also spotted the code in remap_ssa_name that is supposed to handle
> this it seems and for the testcase we only give up because the PARM_DECL is
> remapped to a VAR_DECL. So I suppose it is to be handled via the
> debug-args stuff
> which probably lacks in the area of versioning.
>
> Your patch feels like it adds stuff ontop of existing mechanisms that
> should "just work"
> with the correct setup at the correct places...
>
Hmm, I realized that I may be complicating things, by trying to do an
optimal fix in a single patch, so I decided to write two patches, one
with a fix, and then one improving the fix to be more optimal.
Also, I suspect that the "just work" approach is this:
...
# DEBUG D#8 s=> iD.1900
# DEBUG iD.1949 => D#8
# DEBUG D#6 s=> iD.1949
...
whereas previously I tried to map 'D#6' on iD.1900 directly.
First patch OK for trunk?
[debug] Handle debug references to skipped params
When compiling guality/vla-1.c with -O3 -g, vla a in f1 is optimized away, but
f1 still contains a debug expression describing the upper bound of the vla
(D.1914):
...
__attribute__((noinline))
f1 (intD.6 iD.1900)
{
<bb 2>
saved_stack.1_2 = __builtin_stack_save ();
# DEBUG BEGIN_STMT
# DEBUG D#3 => i_1(D) + 1
# DEBUG D#2 => (long intD.8) D#3
# DEBUG D#1 => D#2 + -1
# DEBUG D.1914 => (sizetype) D#1
...
Then f1 is cloned to a version f1.constprop with no parameters, eliminating
parameter i, and 'DEBUG D#3 => i_1(D) + 1' turns into 'D#3 => NULL'.
This patch fixes that by defining debug expressions for default defs of
eliminated parameters in remap_ssa_name:
...
__attribute__((noinline))
f1.constprop ()
{
intD.6 iD.1949;
<bb 3>
# DEBUG D#8 s=> iD.1900
# DEBUG iD.1949 => D#8
<bb 2>
+ # DEBUG D#6 s=> iD.1949
saved_stack.1_1 = __builtin_stack_save ();
# DEBUG BEGIN_STMT
- # DEBUG D#3 => NULL
+ # DEBUG D#3 => D#6 + 1
# DEBUG D#2 => (long intD.8) D#3
# DEBUG D#1 => D#2 + -1
# DEBUG D.1951 => (sizetype) D#1
...
Bootstrapped and reg-tested on x86_64.
2018-07-07 Tom de Vries <tdevries@suse.de>
* cfgexpand.c (expand_debug_source_expr): Handle VAR_DECL.
* tree-inline.c (remap_ssa_name): Handle default def ssa_name mapping
onto VAR_DECL with abstract origin.
* gcc.dg/vla-1.c: New test.
---
gcc/cfgexpand.c | 4 ++++
gcc/testsuite/gcc.dg/vla-1.c | 25 +++++++++++++++++++++++++
gcc/tree-inline.c | 4 +++-
3 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 9b91279282e..d6e3c382085 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -5141,6 +5141,10 @@ expand_debug_source_expr (tree exp)
switch (TREE_CODE (exp))
{
+ case VAR_DECL:
+ if (DECL_ABSTRACT_ORIGIN (exp))
+ return expand_debug_source_expr (DECL_ABSTRACT_ORIGIN (exp));
+ break;
case PARM_DECL:
{
mode = DECL_MODE (exp);
diff --git a/gcc/testsuite/gcc.dg/vla-1.c b/gcc/testsuite/gcc.dg/vla-1.c
new file mode 100644
index 00000000000..0c19feffd2b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-1.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-g -O3 -fdump-tree-optimized" } */
+
+int __attribute__((noinline))
+f1 (int i)
+{
+ char a[i + 1];
+ char b[i + 2];
+ b[1] = 3;
+ a[0] = 5;
+ return a[0] + b[1];
+}
+
+int
+main ()
+{
+ volatile int j;
+ int x = 5;
+ j = f1 (x);
+ return 0;
+}
+
+/* One debug source bind is generated for the parameter, and two to describe the
+ sizes of a and b. */
+/* { dg-final { scan-tree-dump-times " s=> i" 3 "optimized" } } */
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 427ef959740..6fbd8c3ca61 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -208,7 +208,9 @@ remap_ssa_name (tree name, copy_body_data *id)
n = id->decl_map->get (val);
if (n != NULL)
val = *n;
- if (TREE_CODE (val) != PARM_DECL)
+ if (TREE_CODE (val) != PARM_DECL
+ && !(TREE_CODE (val) == VAR_DECL
+ && DECL_ABSTRACT_ORIGIN (val)))
{
processing_debug_stmt = -1;
return name;