[ARM] PR target/67929 Tighten vfp3_const_double_for_bits checks

	PR target/67929
	* config/arm/arm.c (vfp3_const_double_for_bits): Rewrite.
	* config/arm/constraints.md (Dp): Update callsite.
	* config/arm/predicates.md (const_double_vcvt_power_of_two): Likewise.

	* gcc.target/arm/pr67929_1.c: New test.

From-SVN: r229436

3 files changed, 28 insertions, 15 deletions

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index a379121..a598c84 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -27747,25 +27747,37 @@ vfp3_const_double_for_fract_bits (rtx operand)
   return 0;
 }
 
+/* If X is a CONST_DOUBLE with a value that is a power of 2 whose
+   log2 is in [1, 32], return that log2.  Otherwise return -1.
+   This is used in the patterns for vcvt.s32.f32 floating-point to
+   fixed-point conversions.  */
+
 int
-vfp3_const_double_for_bits (rtx operand)
+vfp3_const_double_for_bits (rtx x)
 {
-  const REAL_VALUE_TYPE *r0;
+  const REAL_VALUE_TYPE *r;
 
-  if (!CONST_DOUBLE_P (operand))
-    return 0;
+  if (!CONST_DOUBLE_P (x))
+    return -1;
 
-  r0 = CONST_DOUBLE_REAL_VALUE (operand);
-  if (exact_real_truncate (DFmode, r0))
-    {
-      HOST_WIDE_INT value = real_to_integer (r0);
-      value = value & 0xffffffff;
-      if ((value != 0) && ( (value & (value - 1)) == 0))
-	return int_log2 (value);
-    }
+  r = CONST_DOUBLE_REAL_VALUE (x);
 
-  return 0;
+  if (REAL_VALUE_NEGATIVE (*r)
+      || REAL_VALUE_ISNAN (*r)
+      || REAL_VALUE_ISINF (*r)
+      || !real_isinteger (r, SFmode))
+    return -1;
+
+  HOST_WIDE_INT hwint = exact_log2 (real_to_integer (r));
+
+/* The exact_log2 above will have returned -1 if this is
+   not an exact log2.  */
+  if (!IN_RANGE (hwint, 1, 32))
+    return -1;
+
+  return hwint;
 }
+
 
 /* Emit a memory barrier around an atomic sequence according to MODEL.  */
 
diff --git a/gcc/config/arm/constraints.md b/gcc/config/arm/constraints.md
index e24858f..901cfe5 100644
--- a/gcc/config/arm/constraints.md
+++ b/gcc/config/arm/constraints.md
@@ -339,7 +339,8 @@
  "@internal
   In ARM/ Thumb2 a const_double which can be used with a vcvt.s32.f32 with bits operation"
   (and (match_code "const_double")
-       (match_test "TARGET_32BIT && TARGET_VFP && vfp3_const_double_for_bits (op)")))
+       (match_test "TARGET_32BIT && TARGET_VFP
+		    && vfp3_const_double_for_bits (op) > 0")))
 
 (define_register_constraint "Ts" "(arm_restrict_it) ? LO_REGS : GENERAL_REGS"
  "For arm_restrict_it the core registers @code{r0}-@code{r7}.  GENERAL_REGS otherwise.")
diff --git a/gcc/config/arm/predicates.md b/gcc/config/arm/predicates.md
index 08cc899..48e4ba8 100644
--- a/gcc/config/arm/predicates.md
+++ b/gcc/config/arm/predicates.md
@@ -668,7 +668,7 @@
 (define_predicate "const_double_vcvt_power_of_two"
   (and (match_code "const_double")
        (match_test "TARGET_32BIT && TARGET_VFP
-                   && vfp3_const_double_for_bits (op)")))
+		    && vfp3_const_double_for_bits (op) > 0")))
 
 (define_predicate "neon_struct_operand"
   (and (match_code "mem")