FreeChainXenon/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

middle-end/100786 - constant folding from incompatible alias

Browse source 
The following avoids us ICEing doing constant folding from variables
with aliases of different types.  The issue appears both in
folding and CCP and FRE can do more fancy stuff to still constant
fold cases where the load is smaller than the initializer so
defer it to there.

2022-01-20  Richard Biener  <rguenther@suse.de>

	PR middle-end/100786
	* gimple-fold.cc (get_symbol_constant_value): Only return
	values of compatible type to the symbol.

	* gcc.dg/torture/pr100786.c: New testcase.
This commit is contained in:
Richard Biener 2022-01-20 14:25:51 +01:00
parent 62eb400b51
commit 5c12507f5d
2 changed files with 12 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
gcc/gimple-fold.cc
View file

@ -291,7 +291,9 @@ get_symbol_constant_value (tree sym)
if (val)
{
val = canonicalize_constructor_val (unshare_expr (val), sym);
if (val && is_gimple_min_invariant (val))
if (val
&& is_gimple_min_invariant (val)
&& useless_type_conversion_p (TREE_TYPE (sym), TREE_TYPE (val)))
return val;
else
return NULL_TREE;

9
gcc/testsuite/gcc.dg/torture/pr100786.c Normal file
View file

@ -0,0 +1,9 @@
/* { dg-do compile } */
const double a = 0;
extern int b __attribute__((alias("a")));
void inc() { b++; }
const int a2 = 0;
extern double b2 __attribute__((alias("a2")));
void inc2() { b2+=1; }