[COMMITTED] [PR tree-optimization/107312] Make range_true_and_false work with 1-bit signed types.

[Aldy Hernandez <aldyh@redhat.com>]

range_true_and_false() returns a range of [0,1], which for a 1-bit
signed integer gets passed to the irange setter as [0, -1].  These
endpoints are out of order and cause an ICE.  Through some dumb luck,
the legacy code swaps out of order endpoints, because old VRP would
sometimes pass endpoints reversed, depending on the setter to fix
them.  This swapping does not happen for non-legacy, hence the ICE.

The right thing to do (apart from killing legacy and 1-bit signed
integers ;-)), is to avoid passing out of order endpoints for 1-bit
signed integers.  For that matter, a range of [-1, 0] (signed) or
[0, 1] (unsigned) is just varying.

	PR tree-optimization/107312

gcc/ChangeLog:

	* range.h (range_true_and_false): Special case 1-bit signed types.
	* value-range.cc (range_tests_misc): New test.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr107312.c: New test.
---
 gcc/range.h                              |  2 ++
 gcc/testsuite/gcc.target/i386/pr107312.c | 11 +++++++++++
 gcc/value-range.cc                       |  2 ++
 3 files changed, 15 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr107312.c

diff --git a/gcc/range.h b/gcc/range.h
index 8138d6f5515..ba3a6b2516f 100644
--- a/gcc/range.h
+++ b/gcc/range.h
@@ -50,6 +50,8 @@ static inline int_range<1>
 range_true_and_false (tree type)
 {
   unsigned prec = TYPE_PRECISION (type);
+  if (prec == 1)
+    return int_range<2> (type);
   return int_range<2> (type, wi::zero (prec), wi::one (prec));
 }
 
diff --git a/gcc/testsuite/gcc.target/i386/pr107312.c b/gcc/testsuite/gcc.target/i386/pr107312.c
new file mode 100644
index 00000000000..b4180e3bd7d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr107312.c
@@ -0,0 +1,11 @@
+// { dg-do compile }
+// { dg-options "-mavx512vbmi -O1 -ftree-loop-vectorize" }
+
+void
+foo (_Float16 *r, short int *a)
+{
+  int i;
+
+  for (i = 0; i < 32; ++i)
+    r[i] = !!a[i];
+}
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 90d5e660684..511cd0ad767 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -3437,6 +3437,8 @@ range_tests_misc ()
     max.union_ (min);
     ASSERT_TRUE (max.varying_p ());
   }
+  // Test that we can set a range of true+false for a 1-bit signed int.
+  r0 = range_true_and_false (one_bit_type);
 
   // Test inversion of 1-bit signed integers.
   {
-- 
2.37.3