[gcc r13-8619] ipa: Avoid duplicate replacements in IPA-SRA transformation phase

[gcc r13-8619] ipa: Avoid duplicate replacements in IPA-SRA transformation phase

[Martin Jambor]

https://gcc.gnu.org/g:8a3784adf5cd873ca295a5a011d8623338ff3976

commit r13-8619-g8a3784adf5cd873ca295a5a011d8623338ff3976
Author: Martin Jambor <mjambor@suse.cz>
Date:   Fri Apr 19 16:48:12 2024 +0200

    ipa: Avoid duplicate replacements in IPA-SRA transformation phase
    
    When the analysis part of IPA-SRA figures out that it would split out
    a scalar part of an aggregate which is known by IPA-CP to contain a
    known constant, it skips it knowing that the transformation part looks
    at IPA-CP aggregate results too and does the right thing (which can
    include doing the propagation in GIMPLE because that is the last
    moment the parameter exists).
    
    However, when IPA-SRA wants to split out a smaller aggregate out
    of an aggregate, which happens to be of the same size as a known
    scalar constant at the same offset, the transformation bit fails to
    recognize the situation, tries to do both splitting and constant
    propagation and in PR 111571 testcase creates a nonsensical call
    statement on which the call redirection then ICEs.
    
    Fixed by making sure we don't try to do two replacements of the same
    part of the same parameter.
    
    The look-up among replacements requires these are sorted and this
    patch just sorts them if they are not already sorted before each new
    look-up.  The worst number of sortings that can happen is number of
    parameters which are both split and have aggregate constants times
    param_ipa_max_agg_items (default 16).  I don't think complicating the
    source code to optimize for this unlikely case is worth it but if need
    be, it can of course be done.
    
    gcc/ChangeLog:
    
    2024-03-15  Martin Jambor  <mjambor@suse.cz>
    
            PR ipa/111571
            * ipa-param-manipulation.cc
            (ipa_param_body_adjustments::common_initialization): Avoid creating
            duplicate replacement entries.
    
    gcc/testsuite/ChangeLog:
    
    2024-03-15  Martin Jambor  <mjambor@suse.cz>
    
            PR ipa/111571
            * gcc.dg/ipa/pr111571.c: New test.
    
    (cherry picked from commit ca56b43105fc09021ec445f1978a17cd85ae5e0c)

Diff:
---
 gcc/ipa-param-manipulation.cc       | 16 ++++++++++++++++
 gcc/testsuite/gcc.dg/ipa/pr111571.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/gcc/ipa-param-manipulation.cc b/gcc/ipa-param-manipulation.cc
index 182f0c6741e..e4f626ae95e 100644
--- a/gcc/ipa-param-manipulation.cc
+++ b/gcc/ipa-param-manipulation.cc
@@ -1484,6 +1484,22 @@ ipa_param_body_adjustments::common_initialization (tree old_fndecl,
 		     replacement with a constant (for split aggregates passed
 		     by value).  */
 
+		  if (split[parm_num])
+		    {
+		      /* We must be careful not to add a duplicate
+			 replacement. */
+		      sort_replacements ();
+		      ipa_param_body_replacement *pbr
+			= lookup_replacement_1 (m_oparms[parm_num],
+						av.unit_offset);
+		      if (pbr)
+			{
+			  /* Otherwise IPA-SRA should have bailed out.  */
+			  gcc_assert (AGGREGATE_TYPE_P (TREE_TYPE (pbr->repl)));
+			  continue;
+			}
+		    }
+
 		  tree repl;
 		  if (av.by_ref)
 		    repl = av.value;
diff --git a/gcc/testsuite/gcc.dg/ipa/pr111571.c b/gcc/testsuite/gcc.dg/ipa/pr111571.c
new file mode 100644
index 00000000000..2a4adc608db
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr111571.c
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-options "-O2"  } */
+
+struct a {
+  int b;
+};
+struct c {
+  long d;
+  struct a e;
+  long f;
+};
+int g, h, i;
+int j() {return 0;}
+static void k(struct a l, int p) {
+  if (h)
+    g = 0;
+  for (; g; g = j())
+    if (l.b)
+      break;
+}
+static void m(struct c l) {
+  k(l.e, l.f);
+  for (;; --i)
+    ;
+}
+int main() {
+  struct c n = {10, 9};
+  m(n);
+}