@@ -8320,6 +8320,11 @@ alg_usable_p (enum stringop_alg alg, bool memset, bool have_as)
{
if (alg == no_stringop)
return false;
+ /* It is not possible to use a library call if we have non-default
+ address space. We can do better than the generic byte-at-a-time
+ loop, used as a fallback. */
+ if (alg == libcall && have_as)
+ return false;
if (alg == vector_loop)
return TARGET_SSE || TARGET_AVX;
/* Algorithms using the rep prefix want at least edi and ecx;
@@ -8494,8 +8499,12 @@ decide_alg (HOST_WIDE_INT count, HOST_WIDE_INT expected_size,
gcc_assert (alg != libcall);
return alg;
}
+
+ /* Try to use some reasonable fallback algorithm. Note that for
+ non-default address spaces we default to a loop instead of
+ a libcall. */
return (alg_usable_p (algs->unknown_size, memset, have_as)
- ? algs->unknown_size : libcall);
+ ? algs->unknown_size : have_as ? loop : libcall);
}
/* Decide on alignment. We know that the operand is already aligned to ALIGN
new file mode 100644
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand -mno-sse" } */
+
+struct a { long arr[30]; };
+
+__seg_gs struct a m;
+void bar (struct a *dst) { *dst = m; }
+
+/* { dg-final { scan-rtl-dump-not "libcall" "expand" } } */
The stringop strategy selection algorithm falls back to a libcall strategy when it exhausts its pool of available strategies. The memory area copy function (memcpy) is not available from the system library for non-default address spaces, so the compiler emits the most trivial byte-at-a-time copy loop instead. The compiler should instead emit an optimized copy loop as a fallback for non-default address spaces. PR target/111657 gcc/ChangeLog: * config/i386/i386-expand.cc (alg_usable_p): Reject libcall strategy for non-default address spaces. (decide_alg): Use loop strategy as a fallback strategy for non-default address spaces. gcc/testsuite/ChangeLog: * gcc.target/i386/pr111657.c: New test. Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.