From 3c5bccb608c665ac3f62adb1817c42c845812428 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Sat, 24 Sep 2022 09:19:26 +0200
Subject: [PATCH] openmp, c: Tighten up c_tree_equal [PR106981]

This patch changes c_tree_equal to work more like cp_tree_equal, be
more strict in what it accepts.  The ICE on the first testcase was
due to INTEGER_CST wi::wide (t1) == wi::wide (t2) comparison which
ICEs if the two constants have different precision, but as the second
testcase shows, being too lenient in it can also lead to miscompilation
of valid OpenMP programs where we think certain expression is the same
even when it isn't and can be guaranteed at runtime to represent different
memory location.  So, the patch looks through only NON_LVALUE_EXPRs
and for constants as well as casts requires that the types match before
actually comparing the constant values or recursing on the cast operands.

2022-09-24  Jakub Jelinek  <jakub@redhat.com>

	PR c/106981
gcc/c/
	* c-typeck.cc (c_tree_equal): Only strip NON_LVALUE_EXPRs at the
	start.  For CONSTANT_CLASS_P or CASE_CONVERT: return false if t1 and
	t2 have different types.
gcc/testsuite/
	* c-c++-common/gomp/pr106981.c: New test.
libgomp/
	* testsuite/libgomp.c-c++-common/pr106981.c: New test.
---
 gcc/c/c-typeck.cc                             | 16 ++++++++++------
 gcc/testsuite/c-c++-common/gomp/pr106981.c    |  9 +++++++++
 .../testsuite/libgomp.c-c++-common/pr106981.c | 19 +++++++++++++++++++
 3 files changed, 38 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/gomp/pr106981.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/pr106981.c

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index b4ef090836d..ac242b5ed13 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -16051,14 +16051,10 @@ c_tree_equal (tree t1, tree t2)
   if (!t1 || !t2)
     return false;
 
-  for (code1 = TREE_CODE (t1);
-       CONVERT_EXPR_CODE_P (code1)
-	 || code1 == NON_LVALUE_EXPR;
+  for (code1 = TREE_CODE (t1); code1 == NON_LVALUE_EXPR;
        code1 = TREE_CODE (t1))
     t1 = TREE_OPERAND (t1, 0);
-  for (code2 = TREE_CODE (t2);
-       CONVERT_EXPR_CODE_P (code2)
-	 || code2 == NON_LVALUE_EXPR;
+  for (code2 = TREE_CODE (t2); code2 == NON_LVALUE_EXPR;
        code2 = TREE_CODE (t2))
     t2 = TREE_OPERAND (t2, 0);
 
@@ -16069,6 +16065,9 @@ c_tree_equal (tree t1, tree t2)
   if (code1 != code2)
     return false;
 
+  if (CONSTANT_CLASS_P (t1) && !comptypes (TREE_TYPE (t1), TREE_TYPE (t2)))
+    return false;
+
   switch (code1)
     {
     case INTEGER_CST:
@@ -16188,6 +16187,11 @@ c_tree_equal (tree t1, tree t2)
 	return true;
       }
 
+    CASE_CONVERT:
+      if (!comptypes (TREE_TYPE (t1), TREE_TYPE (t2)))
+	return false;
+      break;
+
     default:
       break;
     }
diff --git a/gcc/testsuite/c-c++-common/gomp/pr106981.c b/gcc/testsuite/c-c++-common/gomp/pr106981.c
new file mode 100644
index 00000000000..a21d3c2029d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/pr106981.c
@@ -0,0 +1,9 @@
+/* PR c/106981 */
+/* { dg-do compile } */
+
+void
+foo (int a, double *b, double *c, double *d, long long e)
+{
+#pragma omp atomic capture
+  c[a] = d[((int) (e / 10 + 1))] = b[a] + d[((int) e / 10 + 1)];	/* { dg-error "invalid form" } */
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/pr106981.c b/libgomp/testsuite/libgomp.c-c++-common/pr106981.c
new file mode 100644
index 00000000000..ed48d2774f2
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/pr106981.c
@@ -0,0 +1,19 @@
+/* PR c/106981 */
+
+int
+main ()
+{
+  int a[0x101];
+  unsigned int b = 0x100;
+  if ((unsigned char) b || (unsigned short) b != 0x100)
+    return 0;
+  a[0] = 0;
+  a[0x100] = 42;
+  #pragma omp atomic update
+  a[(unsigned char) b] = a[(unsigned short) b] + a[(unsigned char) b];
+  #pragma omp atomic update
+  a[(unsigned char) b] = a[(unsigned char) b] + a[(unsigned short) b];
+  if (a[0] != 84 || a[0x100] != 42)
+    __builtin_abort ();
+  return 0;
+}