[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.

2018-07-09  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.

From-SVN: r262510

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8966da1051bd11021254e9c0ca1bbd83f7c164a4..8add29b83a34b589a03cc36cb29acd219cd2e747 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-07-09  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.
+
 2018-07-07  Jim Wilson  <jimw@sifive.com>
 
        * config/riscv/riscv.c (TARGET_CUSTOM_FUNCTION_DESCRIPTORS): New.

diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 9b91279282e1c6956c8b3699f13036c401ea1dcd..d6e3c382085106f698df85e939136ae7d3d196f5 100644 (file)
--- 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/ChangeLog b/gcc/testsuite/ChangeLog
index 04d705d68d2bd325f17b0991f10709fb595f342a..988fac11b05b87e446ce5cce55e19eebb0a881b7 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2018-07-09  Tom de Vries  <tdevries@suse.de>
+
+       * gcc.dg/vla-1.c: New test.
+
 2018-07-07  Tom de Vries  <tdevries@suse.de>
 
        * gcc.misc-tests/options.exp (check_for_all_options): Clean up dump

diff --git a/gcc/testsuite/gcc.dg/vla-1.c b/gcc/testsuite/gcc.dg/vla-1.c
new file mode 100644 (file)
index 0000000..56437ae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-1.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-g -O3 -fdump-tree-optimized -fvar-tracking-assignments -fno-selective-scheduling -fno-selective-scheduling2" } */
+
+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 427ef959740b10d8aebfc33976a7266008fbb0da..45aba8171a638cb58f2f454364c61f4782116274 100644 (file)
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -208,7 +208,8 @@ 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
+             && !(VAR_P (val) && DECL_ABSTRACT_ORIGIN (val)))
            {
              processing_debug_stmt = -1;
              return name;