https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80262
Bug ID: 80262
Summary: address space gets lost in memory access
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: stefan at reservoir dot com
Target Milestone: ---
Created attachment 41086
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41086&action=edit
The source program
For an out-of-tree target that supports address spaces the address space is
lost during early sra in the following example when compiled with -O3:
---- cut ----
typedef int v4si __attribute__ (( __vector_size__ (16) ));
typedef struct {
v4si v;
} S1;
S1 clearS1() { S1 s1 = { 0 }; return s1; }
typedef struct {
S1 s2[4];
} S2;
void initS2(__ea S2* p, int i) {
p->s2[i] = clearS1();
}
---- cut ----
At the end of forwprop1, in initS2 there still is the reference to p->s2[i],
but when esra creates a replacement for the result value of the inlined
clearS1, the memory reference is rewritten dropping the address space (see the
attached dumps).
Of course, I may have introduced this bug with my changes, maybe someone with a
target that supports address spaces can confirm this problem?
The problem appears to be due to the type returned by reference_alias_ptr_type
in this case: it builds a pointer to the TYPE_MAIN_VARIANT, thus dropping the
address space qualifier. The following patch may solve this problem:
---- cut ----
--- orig_gcc-6.3.0/gcc/alias.c 2016-12-07 22:47:48.000000000 +0000
+++ gcc/gcc/alias.c 2017-03-29 13:42:15.192688629 +0000
@@ -784,7 +784,13 @@
|| TREE_CODE (t) == TARGET_MEM_REF)
return TREE_TYPE (TREE_OPERAND (t, 1));
else
- return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t)));
+ {
+ addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (t));
+ tree tem = TYPE_MAIN_VARIANT (TREE_TYPE (t));
+ if (!ADDR_SPACE_GENERIC_P (as))
+ tem = build_qualified_type (tem, ENCODE_QUAL_ADDR_SPACE (as));
+ return build_pointer_type (tem);
+ }
}
/* Return whether the pointer-types T1 and T2 used to determine
---- cut ----
