In gimple_fold_indirect_ref, we STRIP_NOPS, find the ADDR_EXPR, and fold
everything away.
I can't imagine it ever being correct to drop an address space change between
pointers, so I've modified tree_nop_conversion_p. Anything else seems to
require more checks every places we use STRIP_NOPS.
Ok?
r~
diff --git a/gcc/testsuite/gcc.target/i386/addr-space-4.c
b/gcc/testsuite/gcc.target/i386/addr-space-4.c
new file mode 100644
index 0000000..3e0966d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/addr-space-4.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+/* { dg-final { scan-assembler "gs:" } } */
+
+#define uintptr_t __SIZE_TYPE__
+
+struct S { int a, b, c; };
+
+extern struct S __seg_gs s;
+
+int foo (void)
+{
+ int r;
+ r = s.c;
+ return r;
+}
diff --git a/gcc/testsuite/gcc.target/i386/addr-space-5.c
b/gcc/testsuite/gcc.target/i386/addr-space-5.c
new file mode 100644
index 0000000..4f73f95
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/addr-space-5.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+/* { dg-final { scan-assembler "gs:" } } */
+
+#define uintptr_t __SIZE_TYPE__
+
+struct S { int a, b, c; };
+
+extern struct S s;
+
+int ct_state3 (void)
+{
+ int r;
+ r = *((int __seg_gs *) (uintptr_t) &s.c);
+ return r;
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index fa7646b..07cb9d9 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -12219,6 +12219,23 @@ block_ultimate_origin (const_tree block)
bool
tree_nop_conversion_p (const_tree outer_type, const_tree inner_type)
{
+ /* Do not strip casts into or out of differing address spaces. */
+ if (POINTER_TYPE_P (outer_type)
+ && TYPE_ADDR_SPACE (TREE_TYPE (outer_type)) != ADDR_SPACE_GENERIC)
+ {
+ if (!POINTER_TYPE_P (inner_type)
+ || (TYPE_ADDR_SPACE (TREE_TYPE (outer_type))
+ != TYPE_ADDR_SPACE (TREE_TYPE (inner_type))))
+ return false;
+ }
+ else if (POINTER_TYPE_P (inner_type)
+ && TYPE_ADDR_SPACE (TREE_TYPE (inner_type)) != ADDR_SPACE_GENERIC)
+ {
+ /* We already know that outer_type is not a pointer with
+ a non-generic address space. */
+ return false;
+ }
+
/* Use precision rather then machine mode when we can, which gives
the correct answer even for submode (bit-field) types. */
if ((INTEGRAL_TYPE_P (outer_type)
