[PATCH] ipa: Avoid another ICE when dealing with type-incompatibilities (PR 108959)

[Martin Jambor <mjambor@suse.cz>]

Hi,

PR 108959 shows one more example where undefined code with type
incompatible accesses to stuff passed in parameters can cause an ICE
because we try to create a VIEW_CONVERT_EXPR of mismatching sizes:

1. IPA-CP tries to push one type from above,

2. IPA-SRA (correctly) decides the parameter is useless because it is
   only used to construct an argument to another function which does not
   use it and so the formal parameter should be removed,

3. but the code reconciling IPA-CP and IPA-SRA transformations still
   wants to perform the IPA-CP and overrides the built-in DCE of
   useless statements and tries to stuff constants into them
   instead, constants of a type with mismatching type and size.

This patch avoids the situation in IPA-SRA by purging the IPA-CP
results from any "aggregate" constants that are passed in parameters
which are detected to be useless.  It also removes IPA value range and
bits information associated with removed parameters stored in the same
structure so that the useless information is not streamed later on.

Bootstrapped and LTO-bootstrapped and tested on x86_64-linux.  OK for
trunk?

Thanks,

Martin



gcc/ChangeLog:

2023-03-22  Martin Jambor  <mjambor@suse.cz>

	PR ipa/108959
	* ipa-sra.cc (zap_useless_ipcp_results): New function.
	(process_isra_node_results): Call it.

gcc/testsuite/ChangeLog:

2023-03-17  Martin Jambor  <mjambor@suse.cz>

	PR ipa/108959
	* gcc.dg/ipa/pr108959.c: New test.
---
 gcc/ipa-sra.cc                      | 66 +++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/ipa/pr108959.c | 22 ++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/ipa/pr108959.c

diff --git a/gcc/ipa-sra.cc b/gcc/ipa-sra.cc
index 3de7d426b7e..7b8260bc9e1 100644
--- a/gcc/ipa-sra.cc
+++ b/gcc/ipa-sra.cc
@@ -4028,6 +4028,70 @@ mark_callers_calls_comdat_local (struct cgraph_node *node, void *)
   return false;
 }
 
+/* Remove any IPA-CP results stored in TS that are associated with removed
+   parameters as marked in IFS. */
+
+static void
+zap_useless_ipcp_results (const isra_func_summary *ifs, ipcp_transformation *ts)
+{
+  unsigned ts_len = vec_safe_length (ts->m_agg_values);
+
+  if (ts_len == 0)
+    return;
+
+  bool removed_item = false;
+  unsigned dst_index = 0;
+
+  for (unsigned i = 0; i < ts_len; i++)
+    {
+      ipa_argagg_value *v = &(*ts->m_agg_values)[i];
+      const isra_param_desc *desc = &(*ifs->m_parameters)[v->index];
+
+      if (!desc->locally_unused)
+	{
+	  if (removed_item)
+	    (*ts->m_agg_values)[dst_index] = *v;
+	  dst_index++;
+	}
+      else
+	removed_item = true;
+    }
+  if (dst_index == 0)
+    {
+      ggc_free (ts->m_agg_values);
+      ts->m_agg_values = NULL;
+    }
+  else if (removed_item)
+    ts->m_agg_values->truncate (dst_index);
+
+  bool useful_bits = false;
+  unsigned count = vec_safe_length (ts->bits);
+  for (unsigned i = 0; i < count; i++)
+    if ((*ts->bits)[i])
+    {
+      const isra_param_desc *desc = &(*ifs->m_parameters)[i];
+      if (desc->locally_unused)
+	(*ts->bits)[i] = NULL;
+      else
+	useful_bits = true;
+    }
+  if (!useful_bits)
+    ts->bits = NULL;
+
+  bool useful_vr = false;
+  count = vec_safe_length (ts->m_vr);
+  for (unsigned i = 0; i < count; i++)
+    if ((*ts->m_vr)[i].known)
+      {
+	const isra_param_desc *desc = &(*ifs->m_parameters)[i];
+	if (desc->locally_unused)
+	  (*ts->m_vr)[i].known = false;
+	else
+	  useful_vr = true;
+      }
+  if (!useful_vr)
+    ts->m_vr = NULL;
+}
 
 /* Do final processing of results of IPA propagation regarding NODE, clone it
    if appropriate.  */
@@ -4080,6 +4144,8 @@ process_isra_node_results (cgraph_node *node,
     }
 
   ipcp_transformation *ipcp_ts = ipcp_get_transformation_summary (node);
+  if (ipcp_ts)
+    zap_useless_ipcp_results (ifs, ipcp_ts);
   vec<ipa_adjusted_param, va_gc> *new_params = NULL;
   if (ipa_param_adjustments *old_adjustments
 	 = cinfo ? cinfo->param_adjustments : NULL)
diff --git a/gcc/testsuite/gcc.dg/ipa/pr108959.c b/gcc/testsuite/gcc.dg/ipa/pr108959.c
new file mode 100644
index 00000000000..cd1f88658ef
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr108959.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+union U2 {
+  long f0;
+  int f1;
+};
+int g_16;
+int g_70[20];
+static int func_61(int) {
+  for (;;)
+    g_70[g_16] = 4;
+}
+static int func_43(int *p_44)
+{
+  func_61(*p_44);
+}
+int main() {
+  union U2 l_38 = {9};
+  int *l_49 = (int *) &l_38;
+  func_43(l_49);
+}
-- 
2.40.0