From: Richard Biener <rguenther@suse.de>
Date: Wed, 31 Aug 2022 12:04:46 +0000 (+0200)
Subject: tree-optimization/90994 - fix uninit diagnostics with EH
X-Git-Tag: basepoints/gcc-14~4897
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=88f29a8aa82f2788baf2f9865940d4c83012c580;p=thirdparty%2Fgcc.git

tree-optimization/90994 - fix uninit diagnostics with EH

r12-3640-g94c12ffac234b2 sneaked in a hack to avoid the diagnostic
for the testcase in PR90994 which sees non-call EH control flow
confusing predicate analysis.  The following patch instead adjusts
the existing code handling EH to handle non-calls and do what I
think was intented.

	PR tree-optimization/90994
	* gimple-predicate-analysis.cc (predicate::init_from_control_deps):
	Ignore exceptional control flow and skip the edge for the purpose of
	predicate generation also for non-calls.

	* g++.dg/torture/pr90994.C: New testcase.
---

diff --git a/gcc/gimple-predicate-analysis.cc b/gcc/gimple-predicate-analysis.cc
index 49500b778328..58eade433dca 100644
--- a/gcc/gimple-predicate-analysis.cc
+++ b/gcc/gimple-predicate-analysis.cc
@@ -41,6 +41,7 @@
 #include "calls.h"
 #include "value-query.h"
 #include "cfganal.h"
+#include "tree-eh.h"
 
 #include "gimple-predicate-analysis.h"
 
@@ -1709,9 +1710,6 @@ predicate::init_from_control_deps (const vec<edge> *dep_chains,
 	    }
 	  /* Get the conditional controlling the bb exit edge.  */
 	  gimple *cond_stmt = gsi_stmt (gsi);
-	  if (is_gimple_call (cond_stmt) && EDGE_COUNT (e->src->succs) >= 2)
-	    /* Ignore EH edge.  Can add assertion on the other edge's flag.  */
-	    continue;
 	  /* Skip this edge if it is bypassing an abort - when the
 	     condition is not satisfied we are neither reaching the
 	     definition nor the use so it isn't meaningful.  Note if
@@ -1819,10 +1817,15 @@ predicate::init_from_control_deps (const vec<edge> *dep_chains,
 		  has_valid_pred = true;
 		}
 	    }
+	  else if (stmt_can_throw_internal (cfun, cond_stmt)
+		   && !(e->flags & EDGE_EH))
+	    /* Ignore the exceptional control flow and proceed as if
+	       E were a fallthru without a controlling predicate for
+	       both the USE (valid) and DEF (questionable) case.  */
+	    has_valid_pred = true;
 	  else
 	    {
-	      /* Disabled.  See PR 90994.
-		 has_valid_pred = false;  */
+	      has_valid_pred = false;
 	      break;
 	    }
 	}
diff --git a/gcc/testsuite/g++.dg/torture/pr90994.C b/gcc/testsuite/g++.dg/torture/pr90994.C
new file mode 100644
index 000000000000..8feb36f2361c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr90994.C
@@ -0,0 +1,40 @@
+// { dg-do compile }
+// { dg-additional-options "-fnon-call-exceptions -Wuninitialized" }
+
+extern void printval(unsigned char v);
+
+inline int readbyte(unsigned char *__restrict presult,
+		    unsigned char volatile *ptr)
+{
+  unsigned char v;
+  try {
+      v = *ptr;
+  } catch (...) {
+      return -1;
+  }
+  *presult = v;
+  return 0;
+}
+
+int incorrectWarning(unsigned char volatile *ptr)
+{
+  int error;
+  unsigned char first;
+  unsigned char second;
+
+  error = readbyte(&first, ptr);
+  asm("\n\n\n\n\n" : : "X" (error != 0));
+  if (error != 0)
+    goto err;
+
+  error = readbyte(&second, ptr);
+  if (error != 0)
+    goto err;
+
+  printval(first);   // { dg-bogus "uninitialized" }
+  printval(second);
+  return 0;
+
+err:
+  return error;
+}