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* [PATCH][PR65802] Mark ifn_va_arg with ECF_NOTHROW
@ 2015-04-21  7:10 Tom de Vries
  2015-04-21  7:28 ` Richard Biener
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Tom de Vries @ 2015-04-21  7:10 UTC (permalink / raw)
  To: Richard Biener; +Cc: GCC Patches

[-- Attachment #1: Type: text/plain, Size: 3537 bytes --]

Hi,

this patch fixes PR65802.

The problem described in PR65802 is that when compiling the test-case (included 
in the patch below) at -O0, the compiler runs into a gcc_assert ICE in 
redirect_eh_edge_1 during pass_cleanup_eh:
...
	  gcc_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr);
...


In more detail, during compilation the ifn_va_arg is marked at as a throwing 
function. That causes exception handling code to be generated, with exception 
handling edges:
...
;; basic block 2, loop depth 0, count 0, freq 0, maybe hot
;;  prev block 0, next block 3, flags: (NEW, REACHABLE)
;;  pred:       ENTRY (FALLTHRU)
[LP 1] # .MEM_5 = VDEF <.MEM_4(D)>
# USE = anything
# CLB = anything
_6 = VA_ARG (&cD.2333, 0B);
;;  succ:       7 (EH)
;;              3 (FALLTHRU)
...

After pass_lower_vaarg, the expansion of ifn_va_arg is spread over several basic 
blocks:
...
;;   basic block 2, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 0, next block 11, flags: (NEW, REACHABLE)
;;    pred:       ENTRY (FALLTHRU)
;;    succ:       11 [100.0%]  (FALLTHRU)

;;   basic block 11, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 2, next block 12, flags: (NEW)
;;    pred:       2 [100.0%]  (FALLTHRU)
   # VUSE <.MEM_4(D)>
   _22 = cD.2333.gp_offsetD.5;
   if (_22 >= 48)
     goto <bb 13> (<L6>);
   else
     goto <bb 12> (<L5>);
;;    succ:       13 (TRUE_VALUE)
;;                12 (FALSE_VALUE)

;;   basic block 12, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 11, next block 13, flags: (NEW)
;;    pred:       11 (FALSE_VALUE)
<L5>:
   # VUSE <.MEM_4(D)>
   _23 = cD.2333.reg_save_areaD.8;
   # VUSE <.MEM_4(D)>
   _24 = cD.2333.gp_offsetD.5;
   _25 = (sizetype) _24;
   addr.1_26 = _23 + _25;
   # VUSE <.MEM_4(D)>
   _27 = cD.2333.gp_offsetD.5;
   _28 = _27 + 8;
   # .MEM_29 = VDEF <.MEM_4(D)>
   cD.2333.gp_offsetD.5 = _28;
   goto <bb 14> (<L7>);
;;    succ:       14 (FALLTHRU)

;;   basic block 13, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 12, next block 14, flags: (NEW)
;;    pred:       11 (TRUE_VALUE)
<L6>:
   # VUSE <.MEM_4(D)>
   _30 = cD.2333.overflow_arg_areaD.7;
   addr.1_31 = _30;
   _32 = _30 + 8;
   # .MEM_33 = VDEF <.MEM_4(D)>
   cD.2333.overflow_arg_areaD.7 = _32;
;;    succ:       14 (FALLTHRU)

;;   basic block 14, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 13, next block 15, flags: (NEW)
;;    pred:       12 (FALLTHRU)
;;                13 (FALLTHRU)
   # .MEM_20 = PHI <.MEM_29(12), .MEM_33(13)>
   # addr.1_21 = PHI <addr.1_26(12), addr.1_31(13)>
<L7>:
   # VUSE <.MEM_20>
   _6 = MEM[(intD.9 * * {ref-all})addr.1_21];
;;    succ:       15 (FALLTHRU)

;;   basic block 15, loop depth 0, count 0, freq 0, maybe hot
;;    prev block 14, next block 3, flags: (NEW)
;;    pred:       14 (FALLTHRU)
;;    succ:       7 (EH)
;;                3 (FALLTHRU)
...

And an ICE is triggered in redirect_eh_edge_1, because the code expects the last 
statement in a BB with an outgoing EH edge to be a throwing statement.

That's obviously not the case, since bb15 is empty. But also all the other 
statements in the expansion are non-throwing.


Looking at the representation before the ifn_va_arg, VA_ARG_EXPR is non-throwing 
(even with -fnon-call-exceptions).

And looking at the situation before the introduction of ifn_va_arg, the 
expansion of VA_ARG_EXPR also didn't contain any throwing statements.


This patch fixes the ICE by marking ifn_va_arg with ECF_NOTHROW.

Bootstrapped and reg-tested on x86_64.

OK for trunk?

Thanks,
- Tom

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[-- Type: text/x-patch, Size: 1481 bytes --]

Mark ifn_va_arg with ECF_NOTHROW

2015-04-20  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/65802
	* internal-fn.def (VA_ARG): Add ECF_NOTROW to flags.

	* g++.dg/pr65802.C: New test.
---
 gcc/internal-fn.def            |  2 +-
 gcc/testsuite/g++.dg/pr65802.C | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/pr65802.C

diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index f557c64..7e19313 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -62,4 +62,4 @@ DEF_INTERNAL_FN (ADD_OVERFLOW, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL)
 DEF_INTERNAL_FN (SUB_OVERFLOW, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL)
 DEF_INTERNAL_FN (MUL_OVERFLOW, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL)
 DEF_INTERNAL_FN (TSAN_FUNC_EXIT, ECF_NOVOPS | ECF_LEAF | ECF_NOTHROW, NULL)
-DEF_INTERNAL_FN (VA_ARG, 0, NULL)
+DEF_INTERNAL_FN (VA_ARG, ECF_NOTHROW, NULL)
diff --git a/gcc/testsuite/g++.dg/pr65802.C b/gcc/testsuite/g++.dg/pr65802.C
new file mode 100644
index 0000000..26e5317
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr65802.C
@@ -0,0 +1,29 @@
+// { dg-do compile }
+// { dg-options "-O0" }
+
+typedef int tf ();
+
+struct S
+{
+  tf m_fn1;
+} a;
+
+void
+fn1 ()
+{
+  try
+    {
+      __builtin_va_list c;
+      {
+	int *d = __builtin_va_arg (c, int *);
+	int **e = &d;
+	__asm__("" : "=d"(e));
+	a.m_fn1 ();
+      }
+      a.m_fn1 ();
+    }
+  catch (...)
+    {
+
+    }
+}
-- 
1.9.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2015-04-26  7:18 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-04-21  7:10 [PATCH][PR65802] Mark ifn_va_arg with ECF_NOTHROW Tom de Vries
2015-04-21  7:28 ` Richard Biener
2015-04-21  7:48 ` Jan Hubicka
2015-04-21  7:50   ` Richard Biener
2015-04-26  7:18     ` Tom de Vries
2015-04-24  3:25 ` Bin.Cheng
2015-04-24 14:27   ` Tom de Vries

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