Hi.
This is updated version of the patch I've sent here:
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00149.html
The patch is about introduction of a new target macro that will
drive how we expand mempcpy. Having a target with
TARGET_HAS_FAST_MEMPCPY_ROUTINE == 1,
we do not expand using memcpy, but mempcy.
Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
@Wilco: Can you please come up with a test-case for aarch64?
Ready to be installed?
Thanks,
Martin
gcc/ChangeLog:
2019-05-09 Martin Liska <mli...@suse.cz>
PR middle-end/90263
* builtins.c (expand_builtin_memory_copy_args): When having a
target with fast mempcpy implementation do now use memcpy.
* config/i386/i386.h (TARGET_HAS_FAST_MEMPCPY_ROUTINE): New.
* defaults.h (TARGET_HAS_FAST_MEMPCPY_ROUTINE): By default
target does not have fast mempcpy routine.
* doc/tm.texi: Document the new hook.
* doc/tm.texi.in: Likewise.
* expr.h (emit_block_move_hints): Add 2 new arguments.
* expr.c (emit_block_move_hints): Bail out when libcall
to memcpy would be used.
gcc/testsuite/ChangeLog:
2019-05-09 Martin Liska <mli...@suse.cz>
* gcc.c-torture/execute/builtins/mempcpy.c: Use mempcpy
without LHS.
---
gcc/builtins.c | 18 ++++++++++++++++--
gcc/config/i386/i386.h | 3 +++
gcc/defaults.h | 7 +++++++
gcc/doc/tm.texi | 5 +++++
gcc/doc/tm.texi.in | 5 +++++
gcc/expr.c | 13 ++++++++++++-
gcc/expr.h | 4 +++-
.../gcc.c-torture/execute/builtins/mempcpy.c | 5 ++---
8 files changed, 53 insertions(+), 7 deletions(-)
diff --git a/gcc/builtins.c b/gcc/builtins.c
index d37d73fc4a0..09d5b540ae8 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -3839,6 +3839,8 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len,
unsigned HOST_WIDE_INT max_size;
unsigned HOST_WIDE_INT probable_max_size;
+ bool is_move_done;
+
/* If DEST is not a pointer type, call the normal function. */
if (dest_align == 0)
return NULL_RTX;
@@ -3888,11 +3890,23 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len,
if (CALL_EXPR_TAILCALL (exp)
&& (retmode == RETURN_BEGIN || target == const0_rtx))
method = BLOCK_OP_TAILCALL;
- if (retmode == RETURN_END && target != const0_rtx)
+ if (TARGET_HAS_FAST_MEMPCPY_ROUTINE
+ && retmode == RETURN_END
+ && target != const0_rtx)
method = BLOCK_OP_NO_LIBCALL_RET;
dest_addr = emit_block_move_hints (dest_mem, src_mem, len_rtx, method,
expected_align, expected_size,
- min_size, max_size, probable_max_size);
+ min_size, max_size, probable_max_size,
+ TARGET_HAS_FAST_MEMPCPY_ROUTINE
+ && retmode == RETURN_END,
+ &is_move_done);
+
+ /* Bail out when a mempcpy call would be expanded as libcall and when
+ we have a target that provides a fast implementation
+ of mempcpy routine. */
+ if (!is_move_done)
+ return NULL_RTX;
+
if (dest_addr == pc_rtx)
return NULL_RTX;
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 3fee779296f..7d20178f432 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -1906,6 +1906,9 @@ typedef struct ix86_args {
#define CLEAR_RATIO(speed) ((speed) ? MIN (6, ix86_cost->move_ratio) : 2)
+/* C library provides fast implementation of mempcpy function. */
+#define TARGET_HAS_FAST_MEMPCPY_ROUTINE 1
+
/* Define if shifts truncate the shift count which implies one can
omit a sign-extension or zero-extension of a shift count.
diff --git a/gcc/defaults.h b/gcc/defaults.h
index b7534256119..eca19d1977f 100644
--- a/gcc/defaults.h
+++ b/gcc/defaults.h
@@ -1348,6 +1348,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
#define SET_RATIO(speed) MOVE_RATIO (speed)
#endif
+/* By default do not generate libcall to mempcpy and rather use
+ libcall to memcpy and adjustment of return value. */
+
+#ifndef TARGET_HAS_FAST_MEMPCPY_ROUTINE
+#define TARGET_HAS_FAST_MEMPCPY_ROUTINE 0
+#endif
+
/* Supply a default definition of STACK_SAVEAREA_MODE for emit_stack_save.
Normally move_insn, so Pmode stack pointer. */
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 8c8978bb13a..cf709dfb843 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -6735,6 +6735,11 @@ optimized for speed rather than size.
If you don't define this, it defaults to the value of @code{MOVE_RATIO}.
@end defmac
+@defmac TARGET_HAS_FAST_MEMPCPY_ROUTINE
+By default do not generate libcall to mempcpy and rather use
+libcall to memcpy and adjustment of return value.
+@end defmac
+
@defmac USE_LOAD_POST_INCREMENT (@var{mode})
A C expression used to determine whether a load postincrement is a good
thing to use for a given mode. Defaults to the value of
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index fe1194ef91a..d05c52a36f9 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4619,6 +4619,11 @@ optimized for speed rather than size.
If you don't define this, it defaults to the value of @code{MOVE_RATIO}.
@end defmac
+@defmac TARGET_HAS_FAST_MEMPCPY_ROUTINE
+By default do not generate libcall to mempcpy and rather use
+libcall to memcpy and adjustment of return value.
+@end defmac
+
@defmac USE_LOAD_POST_INCREMENT (@var{mode})
A C expression used to determine whether a load postincrement is a good
thing to use for a given mode. Defaults to the value of
diff --git a/gcc/expr.c b/gcc/expr.c
index fa15b7eceae..c78bc74c0d9 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1561,12 +1561,16 @@ emit_block_move_hints (rtx x, rtx y, rtx size, enum block_op_methods method,
unsigned int expected_align, HOST_WIDE_INT expected_size,
unsigned HOST_WIDE_INT min_size,
unsigned HOST_WIDE_INT max_size,
- unsigned HOST_WIDE_INT probable_max_size)
+ unsigned HOST_WIDE_INT probable_max_size,
+ bool bail_out_libcall, bool *is_move_done)
{
int may_use_call;
rtx retval = 0;
unsigned int align;
+ if (is_move_done)
+ *is_move_done = true;
+
gcc_assert (size);
if (CONST_INT_P (size) && INTVAL (size) == 0)
return 0;
@@ -1628,6 +1632,13 @@ emit_block_move_hints (rtx x, rtx y, rtx size, enum block_op_methods method,
&& ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (x))
&& ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (y)))
{
+ if (bail_out_libcall)
+ {
+ if (is_move_done)
+ *is_move_done = false;
+ return retval;
+ }
+
if (may_use_call < 0)
return pc_rtx;
diff --git a/gcc/expr.h b/gcc/expr.h
index 17c3962436a..6eb70bf12f1 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -114,7 +114,9 @@ extern rtx emit_block_move_hints (rtx, rtx, rtx, enum block_op_methods,
unsigned int, HOST_WIDE_INT,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT,
- unsigned HOST_WIDE_INT);
+ unsigned HOST_WIDE_INT,
+ bool bail_out_libcall = false,
+ bool *is_move_done = NULL);
extern rtx emit_block_cmp_hints (rtx, rtx, rtx, tree, rtx, bool,
by_pieces_constfn, void *);
extern bool emit_storent_insn (rtx to, rtx from);
diff --git a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
index d82e2232d7b..0b84d229cef 100644
--- a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
+++ b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
@@ -56,9 +56,8 @@ main_test (void)
if (__builtin_mempcpy (p, "ABCDE", 6) != p + 6 || memcmp (p, "ABCDE", 6))
abort ();
- /* If the result of mempcpy is ignored, gcc should use memcpy.
- This should be optimized always, so set inside_main again. */
- inside_main = 1;
+ /* Set inside main in order to not abort because of usafe of mempcpy. */
+ inside_main = 0;
mempcpy (p + 5, s3, 1);
if (memcmp (p, "ABCDEFg", 8))
abort ();
