[gcc r14-1498] varasm: check float size

[Jason Merrill]

https://gcc.gnu.org/g:e7cc4d703bceb9095316c106eba0d1939c6c8044

commit r14-1498-ge7cc4d703bceb9095316c106eba0d1939c6c8044
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Jun 1 14:41:07 2023 -0400

    varasm: check float size
    
    In PR95226, the testcase was failing because we tried to output_constant a
    NOP_EXPR to float from a double REAL_CST, and so we output a double where
    the caller wanted a float.  That doesn't happen anymore, but with the
    output_constant hunk we will ICE in that situation rather than emit the
    wrong number of bytes.
    
    Part of the problem was that initializer_constant_valid_p_1 returned true
    for that NOP_EXPR, because it compared the sizes of integer types but not
    floating-point types.  So the C++ front end assumed it didn't need to fold
    the initializer.
    
            PR c++/95226
    
    gcc/ChangeLog:
    
            * varasm.cc (output_constant) [REAL_TYPE]: Check that sizes match.
            (initializer_constant_valid_p_1): Compare float precision.

Diff:
---
 gcc/varasm.cc | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/gcc/varasm.cc b/gcc/varasm.cc
index 571bb2e2f0e..aee1affc57c 100644
--- a/gcc/varasm.cc
+++ b/gcc/varasm.cc
@@ -4876,16 +4876,16 @@ initializer_constant_valid_p_1 (tree value, tree endtype, tree *cache)
 	tree src_type = TREE_TYPE (src);
 	tree dest_type = TREE_TYPE (value);
 
-	/* Allow conversions between pointer types, floating-point
-	   types, and offset types.  */
+	/* Allow conversions between pointer types and offset types.  */
 	if ((POINTER_TYPE_P (dest_type) && POINTER_TYPE_P (src_type))
-	    || (FLOAT_TYPE_P (dest_type) && FLOAT_TYPE_P (src_type))
 	    || (TREE_CODE (dest_type) == OFFSET_TYPE
 		&& TREE_CODE (src_type) == OFFSET_TYPE))
 	  return initializer_constant_valid_p_1 (src, endtype, cache);
 
-	/* Allow length-preserving conversions between integer types.  */
-	if (INTEGRAL_TYPE_P (dest_type) && INTEGRAL_TYPE_P (src_type)
+	/* Allow length-preserving conversions between integer types and
+	   floating-point types.  */
+	if (((INTEGRAL_TYPE_P (dest_type) && INTEGRAL_TYPE_P (src_type))
+	     || (FLOAT_TYPE_P (dest_type) && FLOAT_TYPE_P (src_type)))
 	    && (TYPE_PRECISION (dest_type) == TYPE_PRECISION (src_type)))
 	  return initializer_constant_valid_p_1 (src, endtype, cache);
 
@@ -5255,6 +5255,7 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align,
       break;
 
     case REAL_TYPE:
+      gcc_assert (size == thissize);
       if (TREE_CODE (exp) != REAL_CST)
 	error ("initializer for floating value is not a floating constant");
       else