re PR rtl-optimization/67218 (Combine incorrectly folds (double) (float) (unsigned))

gcc/
	PR rtl-optimization/67218
	* simplify-rtx.c (exact_int_to_float_conversion_p): New function.
	(simplify_unary_operation_1): Use it.

gcc/testsuite/
	PR rtl-optimization/67218
	* gcc.c-torture/execute/ieee/pr67218.c,
	gcc.target/aarch64/fcvt_int_float_double1.c,
	gcc.target/aarch64/fcvt_int_float_double2.c,
	gcc.target/aarch64/fcvt_int_float_double3.c,
	gcc.target/aarch64/fcvt_int_float_double4.c,
	gcc.target/aarch64/fcvt_uint_float_double1.c,
	gcc.target/aarch64/fcvt_uint_float_double2.c,
	gcc.target/aarch64/fcvt_uint_float_double3.c,
	gcc.target/aarch64/fcvt_uint_float_double4.c: New tests.

From-SVN: r226987

12 files changed, 146 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 90b7893..bd0435e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-08-18  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR rtl-optimization/67218
+	* simplify-rtx.c (exact_int_to_float_conversion_p): New function.
+	(simplify_unary_operation_1): Use it.
+
 2015-08-18  Marek Polacek  <polacek@redhat.com>
 
 	PR middle-end/67222
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index f9352a1..8d86e57 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -829,6 +829,32 @@ simplify_unary_operation (enum rtx_code code, machine_mode mode,
   return simplify_unary_operation_1 (code, mode, op);
 }
 
+/* Return true if FLOAT or UNSIGNED_FLOAT operation OP is known
+   to be exact.  */
+
+static bool
+exact_int_to_float_conversion_p (const_rtx op)
+{
+  int out_bits = significand_size (GET_MODE_INNER (GET_MODE (op)));
+  machine_mode op0_mode = GET_MODE (XEXP (op, 0));
+  /* Constants shouldn't reach here.  */
+  gcc_assert (op0_mode != VOIDmode);
+  int in_prec = GET_MODE_UNIT_PRECISION (op0_mode);
+  int in_bits = in_prec;
+  if (HWI_COMPUTABLE_MODE_P (op0_mode))
+    {
+      unsigned HOST_WIDE_INT nonzero = nonzero_bits (XEXP (op, 0), op0_mode);
+      if (GET_CODE (op) == FLOAT)
+	in_bits -= num_sign_bit_copies (XEXP (op, 0), op0_mode);
+      else if (GET_CODE (op) == UNSIGNED_FLOAT)
+	in_bits = wi::min_precision (wi::uhwi (nonzero, in_prec), UNSIGNED);
+      else
+	gcc_unreachable ();
+      in_bits -= wi::ctz (wi::uhwi (nonzero, in_prec));
+    }
+  return in_bits <= out_bits;
+}
+
 /* Perform some simplifications we can do even if the operands
    aren't constant.  */
 static rtx
@@ -1190,11 +1216,7 @@ simplify_unary_operation_1 (enum rtx_code code, machine_mode mode, rtx op)
       /*  (float_truncate (float x)) is (float x)  */
       if ((GET_CODE (op) == FLOAT || GET_CODE (op) == UNSIGNED_FLOAT)
 	  && (flag_unsafe_math_optimizations
-	      || (SCALAR_FLOAT_MODE_P (GET_MODE (op))
-		  && ((unsigned)significand_size (GET_MODE (op))
-		      >= (GET_MODE_PRECISION (GET_MODE (XEXP (op, 0)))
-			  - num_sign_bit_copies (XEXP (op, 0),
-						 GET_MODE (XEXP (op, 0))))))))
+	      || exact_int_to_float_conversion_p (op)))
 	return simplify_gen_unary (GET_CODE (op), mode,
 				   XEXP (op, 0),
 				   GET_MODE (XEXP (op, 0)));
@@ -1227,11 +1249,7 @@ simplify_unary_operation_1 (enum rtx_code code, machine_mode mode, rtx op)
           */
       if (GET_CODE (op) == FLOAT_EXTEND
 	  || ((GET_CODE (op) == FLOAT || GET_CODE (op) == UNSIGNED_FLOAT)
-	      && SCALAR_FLOAT_MODE_P (GET_MODE (op))
-	      && ((unsigned)significand_size (GET_MODE (op))
-		  >= (GET_MODE_PRECISION (GET_MODE (XEXP (op, 0)))
-		      - num_sign_bit_copies (XEXP (op, 0),
-					     GET_MODE (XEXP (op, 0)))))))
+	      && exact_int_to_float_conversion_p (op)))
 	return simplify_gen_unary (GET_CODE (op), mode,
 				   XEXP (op, 0),
 				   GET_MODE (XEXP (op, 0)));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7cb29d3..af91c7d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,16 @@
+2015-08-18  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR rtl-optimization/67218
+	* gcc.c-torture/execute/ieee/pr67218.c,
+	gcc.target/aarch64/fcvt_int_float_double1.c,
+	gcc.target/aarch64/fcvt_int_float_double2.c,
+	gcc.target/aarch64/fcvt_int_float_double3.c,
+	gcc.target/aarch64/fcvt_int_float_double4.c,
+	gcc.target/aarch64/fcvt_uint_float_double1.c,
+	gcc.target/aarch64/fcvt_uint_float_double2.c,
+	gcc.target/aarch64/fcvt_uint_float_double3.c,
+	gcc.target/aarch64/fcvt_uint_float_double4.c: New tests.
+
 2015-08-18  Matthew Wahab  <matthew.wahab@arm.com>
 
 	* gcc.target/aarch64/atomic-comp-swap-release-acquire.c: Adjust
diff --git a/gcc/testsuite/gcc.c-torture/execute/ieee/pr67218.c b/gcc/testsuite/gcc.c-torture/execute/ieee/pr67218.c
new file mode 100644
index 0000000..2a1260a
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/ieee/pr67218.c
@@ -0,0 +1,15 @@
+extern void abort (void) __attribute__ ((noreturn));
+
+double __attribute__ ((noinline, noclone))
+foo (unsigned int x)
+{
+  return (double) (float) (x | 0xffff0000);
+}
+
+int
+main ()
+{
+  if (foo (1) != 0x1.fffep31)
+    abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double1.c b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double1.c
new file mode 100644
index 0000000..e555b2c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (int x)
+{
+  return (double) (float) (x | (int) 0xff000000);
+}
+
+/* { dg-final { scan-assembler {\tscvtf\td0, w[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double2.c b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double2.c
new file mode 100644
index 0000000..7791b22
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (int x)
+{
+  return (double) (float) (x | (int) 0xfe000000);
+}
+
+/* { dg-final { scan-assembler {\tscvtf\ts[0-9]*, w[0-9]*} } } */
+/* { dg-final { scan-assembler {\tfcvt\td0, s[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double3.c b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double3.c
new file mode 100644
index 0000000..c647742
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double3.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (int x)
+{
+  return (double) (float) ((x & -16) | (int) 0xf0000000);
+}
+
+/* { dg-final { scan-assembler {\tscvtf\td0, w[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double4.c b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double4.c
new file mode 100644
index 0000000..88a5242
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_int_float_double4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (int x)
+{
+  return (double) (float) ((x & -16) | (int) 0xfe00000);
+}
+
+/* { dg-final { scan-assembler {\tscvtf\ts[0-9]*, w[0-9]*} } } */
+/* { dg-final { scan-assembler {\tfcvt\td0, s[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double1.c b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double1.c
new file mode 100644
index 0000000..c1c4920
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (unsigned int x)
+{
+  return (double) (float) (x & 0xffffff);
+}
+
+/* { dg-final { scan-assembler {\t[su]cvtf\td0, w[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double2.c b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double2.c
new file mode 100644
index 0000000..334aae8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (unsigned int x)
+{
+  return (double) (float) (x & 0x1ffffff);
+}
+
+/* { dg-final { scan-assembler {\t[su]cvtf\ts[0-9]*, w[0-9]*} } } */
+/* { dg-final { scan-assembler {\tfcvt\td0, s[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double3.c b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double3.c
new file mode 100644
index 0000000..deb4578
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double3.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (unsigned int x)
+{
+  return (double) (float) (x & 0xffffff00);
+}
+
+/* { dg-final { scan-assembler {\tucvtf\td0, w[0-9]*} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double4.c b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double4.c
new file mode 100644
index 0000000..8f0955c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fcvt_uint_float_double4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+double
+foo (unsigned int x)
+{
+  return (double) (float) (x & 0xffffff80);
+}
+
+/* { dg-final { scan-assembler {\tucvtf\ts[0-9]*, w[0-9]*} } } */
+/* { dg-final { scan-assembler {\tfcvt\td0, s[0-9]*} } } */