From: "H.J. Lu" <hjl.tools@gmail.com>
To: Uros Bizjak <ubizjak@gmail.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] PR target/68937: i686: -fno-plt produces wrong code (maybe only with tailcall
Date: Thu, 17 Dec 2015 16:12:00 -0000 [thread overview]
Message-ID: <CAMe9rOoLARSd6WPy_dr6JTJ+NPdrEW6eLhXZ77-UOuLSL1EcYw@mail.gmail.com> (raw)
In-Reply-To: <CAMe9rOocFnSi5Th1Gtko8Nq7zFUsm-+M0Leus5kt5RD=vO26og@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1753 bytes --]
On Thu, Dec 17, 2015 at 7:50 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Dec 17, 2015 at 5:42 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
>> On Thu, Dec 17, 2015 at 2:00 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Thu, Dec 17, 2015 at 2:04 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
>>>> On Thu, Dec 17, 2015 at 12:29 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>>>>> Since sibcall never returns, we can only use call-clobbered register
>>>>> as GOT base. Otherwise, callee-saved register used as GOT base won't
>>>>> be properly restored.
>>>>>
>>>>> Tested on x86-64 with -m32. OK for trunk?
>>>>
>>>> You don't have to add explicit clobber for members of "CLOBBERED_REGS"
>>>> class, and register_no_elim_operand predicate should be used with "U"
>>>> constraint. Also, please introduce new predicate, similar to how
>>>> GOT_memory_operand is defined and handled.
>>>>
>>>
>>> Here is the updated patch. There is a predicate already,
>>> sibcall_memory_operand. It allows any registers to
>>> be as GOT base, which is the root of our problem.
>>> This patch removes GOT slot from it and handles
>>> sibcall over GOT slot with *sibcall_GOT_32 and
>>> *sibcall_value_GOT_32 patterns. Since I need to
>>> expose constraints on GOT base register to RA,
>>> I have to use 2 operands, GOT base and function
>>> symbol, to describe sibcall over 32-bit GOT slot.
>>
>> Please use
>>
>> (mem:SI (plus:SI
>> (match_operand:SI 0 "register_no_elim_operand" "U")
>> (match_operand:SI 1 "GOT32_symbol_operand")))
>> ...
>>
>> to avoid manual rebuild of the operand.
>>
>
> Is this OK?
>
An updated patch to allow sibcall_memory_operand for RTL
expansion. OK for trunk if there is no regression?
Thanks.
--
H.J.
[-- Attachment #2: 0001-Use-call-clobbered-register-for-sibcall-via-GOT.patch --]
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From dffd3a70b9788174f9b279ff27bf72dbc2384659 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 16 Dec 2015 12:34:57 -0800
Subject: [PATCH] Use call-clobbered register for sibcall via GOT
Since sibcall never returns, we can only use call-clobbered register as
GOT base. Otherwise, callee-saved register used as GOT base won't be
properly restored. sibcall_memory_operand is changed to allow 32-bit
GOT slot only with pseudo register as GOT base for RTL expansion. 2
new patterns, *sibcall_GOT_32 and *sibcall_value_GOT_32, are added to
expose GOT base register to register allocator so that call-clobbered
register will be used for GOT base.
gcc/
PR target/68937
* config/i386/i386.c (ix86_function_ok_for_sibcall): Count
call via GOT slot as indirect call.
* config/i386/i386.md (*sibcall_GOT_32): New pattern.
(*sibcall_value_GOT_32): Likewise.
* config/i386/predicates.md (sibcall_memory_operand): Allow
32-bit GOT slot only with pseudo register as GOT base.
(GOT32_symbol_operand): New predicate.
gcc/testsuite/
PR target/68937
* gcc.target/i386/pr68937-1.c: New test.
* gcc.target/i386/pr68937-2.c: Likewise.
* gcc.target/i386/pr68937-3.c: Likewise.
* gcc.target/i386/pr68937-4.c: Likewise.
* gcc.target/i386/pr68937-5.c: Likewise.
---
gcc/config/i386/i386.c | 4 +++-
gcc/config/i386/i386.md | 33 +++++++++++++++++++++++++++++++
gcc/config/i386/predicates.md | 12 +++++++++++
gcc/testsuite/gcc.target/i386/pr68937-1.c | 13 ++++++++++++
gcc/testsuite/gcc.target/i386/pr68937-2.c | 13 ++++++++++++
gcc/testsuite/gcc.target/i386/pr68937-3.c | 13 ++++++++++++
gcc/testsuite/gcc.target/i386/pr68937-4.c | 13 ++++++++++++
gcc/testsuite/gcc.target/i386/pr68937-5.c | 9 +++++++++
8 files changed, 109 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr68937-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr68937-2.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr68937-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr68937-4.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr68937-5.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index cecea24..0e2bec3 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -6723,8 +6723,10 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
/* If this call is indirect, we'll need to be able to use a
call-clobbered register for the address of the target function.
Make sure that all such registers are not used for passing
- parameters. Note that DLLIMPORT functions are indirect. */
+ parameters. Note that DLLIMPORT functions and call via GOT
+ slot are indirect. */
if (!decl
+ || (flag_pic && !flag_plt)
|| (TARGET_DLLIMPORT_DECL_ATTRIBUTES && DECL_DLLIMPORT_P (decl)))
{
/* Check if regparm >= 3 since arg_reg_available is set to
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 49b2216..6ab8eaa 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -11865,6 +11865,22 @@
"* return ix86_output_call_insn (insn, operands[0]);"
[(set_attr "type" "call")])
+;; Since sibcall never returns, we can only use call-clobbered register
+;; as GOT base.
+(define_insn "*sibcall_GOT_32"
+ [(call (mem:QI
+ (mem:SI (plus:SI
+ (match_operand:SI 0 "register_no_elim_operand" "U")
+ (match_operand:SI 1 "GOT32_symbol_operand"))))
+ (match_operand 2))]
+ "!TARGET_MACHO && !TARGET_64BIT && SIBLING_CALL_P (insn)"
+{
+ rtx fnaddr = gen_rtx_PLUS (Pmode, operands[0], operands[1]);
+ fnaddr = gen_const_mem (Pmode, fnaddr);
+ return ix86_output_call_insn (insn, fnaddr);
+}
+ [(set_attr "type" "call")])
+
(define_insn "*sibcall"
[(call (mem:QI (match_operand:W 0 "sibcall_insn_operand" "UBsBz"))
(match_operand 1))]
@@ -12042,6 +12058,23 @@
"* return ix86_output_call_insn (insn, operands[1]);"
[(set_attr "type" "callv")])
+;; Since sibcall never returns, we can only use call-clobbered register
+;; as GOT base.
+(define_insn "*sibcall_value_GOT_32"
+ [(set (match_operand 0)
+ (call (mem:QI
+ (mem:SI (plus:SI
+ (match_operand:SI 1 "register_no_elim_operand" "U")
+ (match_operand:SI 2 "GOT32_symbol_operand"))))
+ (match_operand 3)))]
+ "!TARGET_MACHO && !TARGET_64BIT && SIBLING_CALL_P (insn)"
+{
+ rtx fnaddr = gen_rtx_PLUS (Pmode, operands[1], operands[2]);
+ fnaddr = gen_const_mem (Pmode, fnaddr);
+ return ix86_output_call_insn (insn, fnaddr);
+}
+ [(set_attr "type" "callv")])
+
(define_insn "*sibcall_value"
[(set (match_operand 0)
(call (mem:QI (match_operand:W 1 "sibcall_insn_operand" "UBsBz"))
diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index 8bdd5d8..f33a53a 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -597,11 +597,17 @@
(match_operand 0 "memory_operand"))))
;; Return true if OP is a memory operands that can be used in sibcalls.
+;; Since sibcall never returns, we can only use call-clobbered register
+;; as GOT base. Allow GOT slot here only with pseudo register as GOT
+;; base. Properly handle sibcall over GOT slot with *sibcall_GOT_32
+;; and *sibcall_value_GOT_32 patterns.
(define_predicate "sibcall_memory_operand"
(and (match_operand 0 "memory_operand")
(match_test "CONSTANT_P (XEXP (op, 0))
|| (GET_CODE (XEXP (op, 0)) == PLUS
&& REG_P (XEXP (XEXP (op, 0), 0))
+ && (REGNO (XEXP (XEXP (op, 0), 0))
+ >= FIRST_PSEUDO_REGISTER)
&& GET_CODE (XEXP (XEXP (op, 0), 1)) == CONST
&& GET_CODE (XEXP (XEXP (XEXP (op, 0), 1), 0)) == UNSPEC
&& XINT (XEXP (XEXP (XEXP (op, 0), 1), 0), 1) == UNSPEC_GOT)")))
@@ -633,6 +639,12 @@
&& XINT (XEXP (op, 0), 1) == UNSPEC_GOTPCREL);
})
+;; Return true if OP is a 32-bit GOT symbol operand.
+(define_predicate "GOT32_symbol_operand"
+ (match_test "GET_CODE (op) == CONST
+ && GET_CODE (XEXP (op, 0)) == UNSPEC
+ && XINT (XEXP (op, 0), 1) == UNSPEC_GOT"))
+
;; Match exactly zero.
(define_predicate "const0_operand"
(match_code "const_int,const_wide_int,const_double,const_vector")
diff --git a/gcc/testsuite/gcc.target/i386/pr68937-1.c b/gcc/testsuite/gcc.target/i386/pr68937-1.c
new file mode 100644
index 0000000..897856b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68937-1.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { *-*-linux* && ia32 } } } */
+/* { dg-options "-O2 -fpic -fno-plt -mregparm=3" } */
+
+extern void bar (int);
+
+void
+foo (int b)
+{
+ bar (b);
+ bar (b);
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*.bar@GOT\\(%e(a|c|d)x\\)" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr68937-2.c b/gcc/testsuite/gcc.target/i386/pr68937-2.c
new file mode 100644
index 0000000..257f4e2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68937-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { *-*-linux* && ia32 } } } */
+/* { dg-options "-O2 -fpic -fno-plt -mregparm=3" } */
+
+extern void bar (int, int);
+
+void
+foo (int a, int b)
+{
+ bar (a, b);
+ bar (a, b);
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*.bar@GOT\\(%e(a|c|d)x\\)" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr68937-3.c b/gcc/testsuite/gcc.target/i386/pr68937-3.c
new file mode 100644
index 0000000..6d8e40f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68937-3.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { *-*-linux* && ia32 } } } */
+/* { dg-options "-O2 -fpic -fno-plt -mregparm=3" } */
+
+extern void bar (int, int, int);
+
+void
+foo (int a, int b, int c)
+{
+ bar (a, b, c);
+ bar (a, b, c);
+}
+
+/* { dg-final { scan-assembler-not "jmp\[ \t\]*.bar@GOT" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr68937-4.c b/gcc/testsuite/gcc.target/i386/pr68937-4.c
new file mode 100644
index 0000000..9c19956
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68937-4.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { *-*-linux* && ia32 } } } */
+/* { dg-options "-O2 -fpic -fno-plt -mregparm=3" } */
+
+extern int bar (int, int);
+
+int
+foo (int a, int b)
+{
+ (void) bar (a, b);
+ return bar (a, b);
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*.bar@GOT\\(%e(a|c|d)x\\)" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr68937-5.c b/gcc/testsuite/gcc.target/i386/pr68937-5.c
new file mode 100644
index 0000000..f7e3ec5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68937-5.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -fpic -fno-plt -funroll-loops" } */
+
+extern void *f();
+void dmi_scan_machine(void) {
+ char *p = f(), *q;
+ for (q = p; q < p + 10; q++)
+ ;
+}
--
2.5.0
next prev parent reply other threads:[~2015-12-17 16:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-16 23:29 H.J. Lu
2015-12-17 10:04 ` Uros Bizjak
2015-12-17 13:00 ` H.J. Lu
2015-12-17 13:42 ` Uros Bizjak
2015-12-17 15:50 ` H.J. Lu
2015-12-17 16:12 ` H.J. Lu [this message]
2015-12-17 18:09 ` H.J. Lu
2015-12-17 21:21 ` Uros Bizjak
2015-12-17 21:59 ` H.J. Lu
2015-12-18 0:55 ` H.J. Lu
2015-12-19 16:19 ` Uros Bizjak
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