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varasm: check float size

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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.
This commit is contained in:
Jason Merrill 2023-06-01 14:41:07 -04:00
parent ef768035ae
commit e7cc4d703b
1 changed files with 6 additions and 5 deletions
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11
gcc/varasm.cc
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@ -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