On 19-06-14 20:41, Richard Henderson wrote:
On 06/19/2014 11:25 AM, Tom de Vries wrote:
On 19-06-14 05:53, Richard Henderson wrote:
On 06/01/2014 03:00 AM, Tom de Vries wrote:
+aarch64_emit_call_insn (rtx pat)
+{
+ rtx insn = emit_call_insn (pat);
+
+ rtx *fusage = &CALL_INSN_FUNCTION_USAGE (insn);
+ clobber_reg (fusage, gen_rtx_REG (word_mode, IP0_REGNUM));
+ clobber_reg (fusage, gen_rtx_REG (word_mode, IP1_REGNUM));
Actually, I'd like to know more about how this is supposed to work.
Why are you only marking the two registers that would be used by a PLT entry,
but not those clobbered by the ld.so trampoline, or indeed the unknown function
that would be called from the PLT.
Oh, I see, looking at the code we do actually follow the cgraph and make sure
it is a direct call with a known destination. So, in fact, it's only the
registers that could be clobbered by ld branch islands (so these two are still
correct for aarch64).
This means the documentation is actually wrong when it mentions PLTs at all.
Yes, if we go from the point of view that the
TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS hooks sole purpose is to enable
the fuse-caller-save optimization.
How about this updated definition ? OK for trunk if re-testing on arm succeeds ?
I did like the doc including mention of "stubs", because they're easy to
forget. How about
Set to true if each call that binds to a local definition explicitly clobbers
or sets all non-fixed registers modified by performing the call. That is, by
the call pattern itself, or by code that might be inserted by the linker
(e.g. stubs, veneers, branch islands), but not including those modifiable by
the callee. The affected registers may be mentioned explicitly in the
call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
The default version of this hook is set to false. The purpose of this hook
is to enable the fuse-caller-save optimization.
Looks good to me. Bootstrapped and committed as attached.
Thanks,
- Tom
2014-06-20 Tom de Vries <t...@codesourcery.com>
* target.def (call_fusage_contains_non_callee_clobbers): Update
definition.
* doc/tm.texi: Regenerate.
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index c272630..45281ae 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -4884,14 +4884,14 @@ Whether this target supports splitting the stack when the options described in @
@cindex miscellaneous register hooks
@deftypevr {Target Hook} bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
-set to true if all the calls in the current function contain clobbers in
-CALL_INSN_FUNCTION_USAGE for the registers that are clobbered by the call
-rather than by the callee, and are not already set or clobbered in the call
-pattern. Examples of such registers are registers used in PLTs and stubs,
-and temporary registers used in the call instruction but not present in the
-rtl pattern. Another way to formulate it is the registers not present in the
-rtl pattern that are clobbered by the call assuming the callee does not
-clobber any register. The default version of this hook is set to false.
+Set to true if each call that binds to a local definition explicitly
+clobbers or sets all non-fixed registers modified by performing the call.
+That is, by the call pattern itself, or by code that might be inserted by the
+linker (e.g. stubs, veneers, branch islands), but not including those
+modifiable by the callee. The affected registers may be mentioned explicitly
+in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+The default version of this hook is set to false. The purpose of this hook
+is to enable the fuse-caller-save optimization.
@end deftypevr
@node Varargs
diff --git a/gcc/target.def b/gcc/target.def
index e455211..ee250e6 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -5128,18 +5128,18 @@ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.",
hook_void_bitmap)
/* Targets should define this target hook to mark that non-callee clobbers are
- present in CALL_INSN_FUNCTION_USAGE for all the calls in the current
- function. */
+ present in CALL_INSN_FUNCTION_USAGE for all the calls that bind to a local
+ definition. */
DEFHOOKPOD
(call_fusage_contains_non_callee_clobbers,
- "set to true if all the calls in the current function contain clobbers in\n\
-CALL_INSN_FUNCTION_USAGE for the registers that are clobbered by the call\n\
-rather than by the callee, and are not already set or clobbered in the call\n\
-pattern. Examples of such registers are registers used in PLTs and stubs,\n\
-and temporary registers used in the call instruction but not present in the\n\
-rtl pattern. Another way to formulate it is the registers not present in the\n\
-rtl pattern that are clobbered by the call assuming the callee does not\n\
-clobber any register. The default version of this hook is set to false.",
+ "Set to true if each call that binds to a local definition explicitly\n\
+clobbers or sets all non-fixed registers modified by performing the call.\n\
+That is, by the call pattern itself, or by code that might be inserted by the\n\
+linker (e.g. stubs, veneers, branch islands), but not including those\n\
+modifiable by the callee. The affected registers may be mentioned explicitly\n\
+in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.\n\
+The default version of this hook is set to false. The purpose of this hook\n\
+is to enable the fuse-caller-save optimization.",
bool,
false)
--
1.9.1
