[gcc r12-2254] tree-optimization/101373 - avoid PRE across externally throwing call

[gcc r12-2254] tree-optimization/101373 - avoid PRE across externally throwing call

[Richard Biener]

https://gcc.gnu.org/g:fedcf3c476aff7533741a1c61071200f0a38cf83

commit r12-2254-gfedcf3c476aff7533741a1c61071200f0a38cf83
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jul 8 09:52:49 2021 +0200

    tree-optimization/101373 - avoid PRE across externally throwing call
    
    PRE already tries to avoid hoisting possibly trapping expressions
    across calls that might not return normally but fails to consider
    const calls that throw externally.  The following fixes that and
    also plugs the hole of trapping references not pruned in case
    they are not catched by the actuall call clobbering it.
    
    At -Os we hit the same issue in RTL PRE and postreload-gcse has
    even more incomplete checks so the patch adjusts both of those
    as well.
    
    2021-07-08  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/101373
            * tree-ssa-pre.c (prune_clobbered_mems): Also prune trapping
            references when the BB may not return.
            (compute_avail): Pass in the function we're working on and
            replace cfun references with it.  Externally throwing
            const calls also possibly terminate the function.
            (pass_pre::execute): Pass down the function we're working on.
            * gcse.c (compute_hash_table_work): Externally throwing
            const/pure calls also need record_last_mem_set_info.
            * postreload-gcse.c (record_opr_changes): Looping or externally
            throwing const/pure calls also need record_last_mem_set_info.
    
            * g++.dg/torture/pr101373.C: New testcase, XFAILed.
            * gnat.dg/opt95.adb: Likewise.

Diff:
---
 gcc/gcse.c                              |  3 ++-
 gcc/postreload-gcse.c                   |  4 +++-
 gcc/testsuite/g++.dg/torture/pr101373.C | 33 +++++++++++++++++++++++++++
 gcc/testsuite/gnat.dg/opt95.adb         | 40 +++++++++++++++++++++++++++++++++
 gcc/tree-ssa-pre.c                      | 34 +++++++++++++++++-----------
 5 files changed, 99 insertions(+), 15 deletions(-)

diff --git a/gcc/gcse.c b/gcc/gcse.c
index ecf7e51aac5..ccd33664af5 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -1537,7 +1537,8 @@ compute_hash_table_work (struct gcse_hash_table_d *table)
 		record_last_reg_set_info (insn, regno);
 
 	      if (! RTL_CONST_OR_PURE_CALL_P (insn)
-		  || RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))
+		  || RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
+		  || can_throw_external (insn))
 		record_last_mem_set_info (insn);
 	    }
 
diff --git a/gcc/postreload-gcse.c b/gcc/postreload-gcse.c
index 0b28247e299..6c95d09a1e5 100644
--- a/gcc/postreload-gcse.c
+++ b/gcc/postreload-gcse.c
@@ -779,7 +779,9 @@ record_opr_changes (rtx_insn *insn)
       EXECUTE_IF_SET_IN_HARD_REG_SET (callee_clobbers, 0, regno, hrsi)
 	record_last_reg_set_info_regno (insn, regno);
 
-      if (! RTL_CONST_OR_PURE_CALL_P (insn))
+      if (! RTL_CONST_OR_PURE_CALL_P (insn)
+	  || RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
+	  || can_throw_external (insn))
 	record_last_mem_set_info (insn);
     }
 }
diff --git a/gcc/testsuite/g++.dg/torture/pr101373.C b/gcc/testsuite/g++.dg/torture/pr101373.C
new file mode 100644
index 00000000000..f8c809739e2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr101373.C
@@ -0,0 +1,33 @@
+// { dg-do run }
+// { dg-xfail-run-if "PR100409" { *-*-* } }
+
+int __attribute__((const,noipa)) foo (int j)
+{
+  if (j != 0)
+    throw 1;
+  return 0;
+}
+
+int __attribute__((noipa)) bar (int *p, int n)
+{
+  int ret = 0;
+  if (n)
+    {
+       foo (n);
+       ret = *p;
+    }
+  ret += *p;
+  return ret;
+}
+
+int main()
+{
+  try
+    {
+      return bar (nullptr, 1);
+    }
+  catch (...)
+    {
+      return 0;
+    }
+}
diff --git a/gcc/testsuite/gnat.dg/opt95.adb b/gcc/testsuite/gnat.dg/opt95.adb
new file mode 100644
index 00000000000..2c72582b3f1
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt95.adb
@@ -0,0 +1,40 @@
+-- { dg-do run }
+-- { dg-options "-O2 -gnatp" }
+
+procedure Opt95 is
+
+  function Foo (J : Integer) return Integer;
+  pragma Pure_Function (Foo);
+  pragma Machine_Attribute (Foo, "noipa");
+
+  function Foo (J : Integer) return Integer is
+  begin
+    if J /= 0 then
+      raise Constraint_Error;
+    end if;
+    return 0;
+  end;
+
+  function Bar (A : access Integer; N : Integer) return Integer;
+  pragma Machine_Attribute (Bar, "noipa");
+
+  function Bar (A : access Integer; N : Integer) return Integer is
+    Ret : Integer := 0;
+    Ret2 : Integer := 0;
+  begin
+    if N /= 0 then
+      Ret2 := Foo (N);
+      Ret := A.all;
+    end if;
+    Ret := Ret + A.all;
+    return Ret + Ret2;
+  end;
+
+  V : Integer;
+  pragma Volatile (V);
+
+begin
+  V := Bar (null, 1);
+exception
+  when Constraint_Error => null;
+end;
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 69141c2f0c9..aa5244e678c 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -2071,6 +2071,13 @@ prune_clobbered_mems (bitmap_set_t set, basic_block block)
 			  && value_dies_in_block_x (expr, block))))
 		to_remove = i;
 	    }
+	  /* If the REFERENCE may trap make sure the block does not contain
+	     a possible exit point.
+	     ???  This is overly conservative if we translate AVAIL_OUT
+	     as the available expression might be after the exit point.  */
+	  if (BB_MAY_NOTRETURN (block)
+	      && vn_reference_may_trap (ref))
+	    to_remove = i;
 	}
       else if (expr->kind == NARY)
 	{
@@ -3860,7 +3867,7 @@ insert (void)
    AVAIL_OUT[BLOCK] = AVAIL_IN[BLOCK] U PHI_GEN[BLOCK] U TMP_GEN[BLOCK].  */
 
 static void
-compute_avail (void)
+compute_avail (function *fun)
 {
 
   basic_block block, son;
@@ -3871,7 +3878,7 @@ compute_avail (void)
 
   /* We pretend that default definitions are defined in the entry block.
      This includes function arguments and the static chain decl.  */
-  FOR_EACH_SSA_NAME (i, name, cfun)
+  FOR_EACH_SSA_NAME (i, name, fun)
     {
       pre_expr e;
       if (!SSA_NAME_IS_DEFAULT_DEF (name)
@@ -3881,31 +3888,31 @@ compute_avail (void)
 
       e = get_or_alloc_expr_for_name (name);
       add_to_value (get_expr_value_id (e), e);
-      bitmap_insert_into_set (TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (cfun)), e);
-      bitmap_value_insert_into_set (AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (cfun)),
+      bitmap_insert_into_set (TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (fun)), e);
+      bitmap_value_insert_into_set (AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (fun)),
 				    e);
     }
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
-      print_bitmap_set (dump_file, TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (cfun)),
+      print_bitmap_set (dump_file, TMP_GEN (ENTRY_BLOCK_PTR_FOR_FN (fun)),
 			"tmp_gen", ENTRY_BLOCK);
-      print_bitmap_set (dump_file, AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (cfun)),
+      print_bitmap_set (dump_file, AVAIL_OUT (ENTRY_BLOCK_PTR_FOR_FN (fun)),
 			"avail_out", ENTRY_BLOCK);
     }
 
   /* Allocate the worklist.  */
-  worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
+  worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun));
 
   /* Seed the algorithm by putting the dominator children of the entry
      block on the worklist.  */
-  for (son = first_dom_son (CDI_DOMINATORS, ENTRY_BLOCK_PTR_FOR_FN (cfun));
+  for (son = first_dom_son (CDI_DOMINATORS, ENTRY_BLOCK_PTR_FOR_FN (fun));
        son;
        son = next_dom_son (CDI_DOMINATORS, son))
     worklist[sp++] = son;
 
-  BB_LIVE_VOP_ON_EXIT (ENTRY_BLOCK_PTR_FOR_FN (cfun))
-    = ssa_default_def (cfun, gimple_vop (cfun));
+  BB_LIVE_VOP_ON_EXIT (ENTRY_BLOCK_PTR_FOR_FN (fun))
+    = ssa_default_def (fun, gimple_vop (fun));
 
   /* Loop until the worklist is empty.  */
   while (sp)
@@ -3970,7 +3977,8 @@ compute_avail (void)
 		 before it.  */
 	      int flags = gimple_call_flags (stmt);
 	      if (!(flags & ECF_CONST)
-		  || (flags & ECF_LOOPING_CONST_OR_PURE))
+		  || (flags & ECF_LOOPING_CONST_OR_PURE)
+		  || stmt_can_throw_external (fun, stmt))
 		BB_MAY_NOTRETURN (block) = 1;
 	    }
 
@@ -3987,7 +3995,7 @@ compute_avail (void)
 	    BB_LIVE_VOP_ON_EXIT (block) = gimple_vdef (stmt);
 
 	  if (gimple_has_side_effects (stmt)
-	      || stmt_could_throw_p (cfun, stmt)
+	      || stmt_could_throw_p (fun, stmt)
 	      || is_gimple_debug (stmt))
 	    continue;
 
@@ -4384,7 +4392,7 @@ pass_pre::execute (function *fun)
      we require AVAIL.  */
   if (n_basic_blocks_for_fn (fun) < 4000)
     {
-      compute_avail ();
+      compute_avail (fun);
       compute_antic ();
       insert ();
     }