c-family: ICE with assume_aligned attribute [PR99062]

We ICE in handle_assume_aligned_attribute since r271338 which added

@@ -2935,8 +2936,8 @@ handle_assume_aligned_attribute (tree *node, tree name, tree args, int,
          /* The misalignment specified by the second argument
             must be non-negative and less than the alignment.  */
          warning (OPT_Wattributes,
-                  "%qE attribute argument %E is not in the range [0, %E)",
-                  name, val, align);
+                  "%qE attribute argument %E is not in the range [0, %wu]",
+                  name, val, tree_to_uhwi (align) - 1);
          *no_add_attrs = true;
          return NULL_TREE;
        }
because align is INT_MIN and tree_to_uhwi asserts tree_fits_uhwi_p -- which
ALIGN does not and the prior tree_fits_shwi_p check is fine with it, as
well as the integer_pow2p check.

Since neither of the arguments to assume_aligned can be negative, I've
hoisted the tree_int_cst_sgn check.  And add the missing "argument"
word to an existing warning.

gcc/c-family/ChangeLog:

	PR c++/99062
	* c-attribs.c (handle_assume_aligned_attribute): Check that the
	alignment argument is non-negative.  Tweak a warning message.

gcc/testsuite/ChangeLog:

	PR c++/99062
	* gcc.dg/attr-assume_aligned-4.c: Adjust dg-warning.
	* g++.dg/ext/attr-assume-aligned.C: New test.

3 files changed, 16 insertions, 4 deletions

diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 84ec86b..0cb51fd 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -3536,11 +3536,18 @@ handle_assume_aligned_attribute (tree *node, tree name, tree args, int,
       if (!tree_fits_shwi_p (val))
 	{
 	  warning (OPT_Wattributes,
-		   "%qE attribute %E is not an integer constant",
+		   "%qE attribute argument %E is not an integer constant",
 		   name, val);
 	  *no_add_attrs = true;
 	  return NULL_TREE;
 	}
+      else if (tree_int_cst_sgn (val) < 0)
+	{
+	  warning (OPT_Wattributes,
+		   "%qE attribute argument %E is not positive", name, val);
+	  *no_add_attrs = true;
+	  return NULL_TREE;
+	}
 
       if (!align)
 	{
@@ -3556,7 +3563,7 @@ handle_assume_aligned_attribute (tree *node, tree name, tree args, int,
 
 	  align = val;
 	}
-      else if (tree_int_cst_sgn (val) < 0 || tree_int_cst_le (align, val))
+      else if (tree_int_cst_le (align, val))
 	{
 	  /* The misalignment specified by the second argument
 	     must be non-negative and less than the alignment.  */
diff --git a/gcc/testsuite/g++.dg/ext/attr-assume-aligned.C b/gcc/testsuite/g++.dg/ext/attr-assume-aligned.C
new file mode 100644
index 0000000..aa57cbb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/attr-assume-aligned.C
@@ -0,0 +1,5 @@
+// PR c++/99062
+// { dg-do compile }
+
+#define INT_MIN (-__INT_MAX__ - 1)
+void *f () __attribute__ ((assume_aligned (INT_MIN, 4))); // { dg-warning "is not positive" }
diff --git a/gcc/testsuite/gcc.dg/attr-assume_aligned-4.c b/gcc/testsuite/gcc.dg/attr-assume_aligned-4.c
index 2571ab8..f6eb6dc 100644
--- a/gcc/testsuite/gcc.dg/attr-assume_aligned-4.c
+++ b/gcc/testsuite/gcc.dg/attr-assume_aligned-4.c
@@ -8,7 +8,7 @@ A (1) void fv_1 (void);       /* { dg-warning ".assume_aligned. attribute ignore
 
 A (1) int fi_1 (void);        /* { dg-warning ".assume_aligned. attribute ignored on a function returning .int." } */
 
-A (-1) void* fpv_m1 (void);   /* { dg-warning ".assume_aligned. attribute argument -1 is not a power of 2" } */
+A (-1) void* fpv_m1 (void);   /* { dg-warning ".assume_aligned. attribute argument -1 is not positive" } */
 
 A (0) void* fpv_0 (void);     /* { dg-warning ".assume_aligned. attribute argument 0 is not a power of 2" } */
 
@@ -23,7 +23,7 @@ A (16385) void* fpv_16kp1 (void);    /* { dg-warning ".assume_aligned. attribute
 
 A (32767) void* fpv_32km1 (void);     /* { dg-warning ".assume_aligned. attribute argument 32767 is not a power of 2" } */
 
-A (4, -1) void* fpv_4_m1 (void);      /* { dg-warning ".assume_aligned. attribute argument -1 is not in the range \\\[0, 3]" } */
+A (4, -1) void* fpv_4_m1 (void);      /* { dg-warning ".assume_aligned. attribute argument -1 is not positive" } */
 
 A (4, 0) void* fpv_4_0 (void);
 A (4, 1) void* fpv_4_1 (void);