public inbox for gcc-patches@gcc.gnu.org
 help / color / mirror / Atom feed
* [PATCH] x86-64: Load external function address via GOT slot
@ 2016-06-20 17:05 H.J. Lu
  2016-06-20 19:13 ` Uros Bizjak
  0 siblings, 1 reply; 10+ messages in thread
From: H.J. Lu @ 2016-06-20 17:05 UTC (permalink / raw)
  To: gcc-patches; +Cc: Jakub Jelinek, Uros Bizjak

Hi,

This patch implements the alternate code sequence recommended in

https://groups.google.com/forum/#!topic/x86-64-abi/de5_KnLHxtI

to load external function address via GOT slot with

movq func@GOTPCREL(%rip), %rax

so that linker won't create an PLT entry for extern function
address.

Tested on x86-64.  OK for trunk?


H.J.
--
gcc/

	PR target/67400
	* config/i386/i386-protos.h (ix86_force_load_from_GOT_p): New.
	* config/i386/i386.c (ix86_force_load_from_GOT_p): New function.
	(ix86_legitimate_address_p): Allow UNSPEC_GOTPCREL if
	ix86_force_load_from_GOT_p returns true.
	(ix86_print_operand_address): Support UNSPEC_GOTPCREL if
	ix86_force_load_from_GOT_p returns true.
	(ix86_expand_move): Load the external function address via the
	GOT slot if ix86_force_load_from_GOT_p returns true.
	* config/i386/predicates.md (x86_64_immediate_operand): Return
	false if ix86_force_load_from_GOT_p returns true.

gcc/testsuite/

	PR target/67400
	* gcc.target/i386/pr67400-1.c: New test.
	* gcc.target/i386/pr67400-2.c: Likewise.
	* gcc.target/i386/pr67400-3.c: Likewise.
	* gcc.target/i386/pr67400-4.c: Likewise.
	* gcc.target/i386/pr67400-5.c: Likewise.
	* gcc.target/i386/pr67400-6.c: Likewise.
---
 gcc/config/i386/i386-protos.h             |  1 +
 gcc/config/i386/i386.c                    | 51 +++++++++++++++++++++++++++++++
 gcc/config/i386/predicates.md             |  4 +++
 gcc/testsuite/gcc.target/i386/pr67400-1.c | 13 ++++++++
 gcc/testsuite/gcc.target/i386/pr67400-2.c | 14 +++++++++
 gcc/testsuite/gcc.target/i386/pr67400-3.c | 16 ++++++++++
 gcc/testsuite/gcc.target/i386/pr67400-4.c | 13 ++++++++
 gcc/testsuite/gcc.target/i386/pr67400-5.c | 11 +++++++
 gcc/testsuite/gcc.target/i386/pr67400-6.c | 13 ++++++++
 9 files changed, 136 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-4.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-5.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67400-6.c

diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index 9fd14f6..8130161 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -70,6 +70,7 @@ extern bool ix86_expand_set_or_movmem (rtx, rtx, rtx, rtx, rtx, rtx,
 extern bool constant_address_p (rtx);
 extern bool legitimate_pic_operand_p (rtx);
 extern bool legitimate_pic_address_disp_p (rtx);
+extern bool ix86_force_load_from_GOT_p (rtx);
 extern void print_reg (rtx, int, FILE*);
 extern void ix86_print_operand (FILE *, rtx, int);
 
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 56a5b9c..c8c5081 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -15182,6 +15182,24 @@ ix86_legitimate_constant_p (machine_mode mode, rtx x)
   return true;
 }
 
+/* True if operand X should be loaded from GOT.  */
+
+bool
+ix86_force_load_from_GOT_p (rtx x)
+{
+  /* External function symbol should be loaded via the GOT slot for
+     -fno-plt.  */
+  return (!flag_plt
+	  && !flag_pic
+	  && ix86_cmodel != CM_LARGE
+	  && TARGET_64BIT
+	  && !TARGET_PECOFF
+	  && !TARGET_MACHO
+	  && GET_CODE (x) == SYMBOL_REF
+	  && SYMBOL_REF_FUNCTION_P (x)
+	  && !SYMBOL_REF_LOCAL_P (x));
+}
+
 /* Determine if it's legal to put X into the constant pool.  This
    is not possible for the address of thread-local symbols, which
    is checked above.  */
@@ -15560,6 +15578,10 @@ ix86_legitimate_address_p (machine_mode, rtx addr, bool strict)
 	    return false;
 
 	  case UNSPEC_GOTPCREL:
+	    gcc_assert (flag_pic
+			|| ix86_force_load_from_GOT_p (XVECEXP (XEXP (disp, 0), 0, 0)));
+	    goto is_legitimate_pic;
+
 	  case UNSPEC_PCREL:
 	    gcc_assert (flag_pic);
 	    goto is_legitimate_pic;
@@ -18130,6 +18152,12 @@ ix86_print_operand_address_as (FILE *file, rtx addr,
 	}
       else if (flag_pic)
 	output_pic_addr_const (file, disp, 0);
+      else if (GET_CODE (disp) == CONST
+	       && GET_CODE (XEXP (disp, 0)) == UNSPEC
+	       && (XINT (XEXP (disp, 0), 1) == UNSPEC_GOTPCREL
+		   || XINT (XEXP (disp, 0), 1) == UNSPEC_GOT)
+	       && ix86_force_load_from_GOT_p (XVECEXP (XEXP (disp, 0), 0, 0)))
+	output_pic_addr_const (file, XEXP (disp, 0), code);
       else
 	output_addr_const (file, disp);
     }
@@ -19448,6 +19476,29 @@ ix86_expand_move (machine_mode mode, rtx operands[])
 	      op1 = convert_to_mode (mode, op1, 1);
 	    }
 	}
+   }
+  else if (ix86_force_load_from_GOT_p (op1))
+    {
+      /* Load the external function address via the GOT slot to
+	 avoid PLT.  */
+      op1 = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, op1),
+			    (TARGET_64BIT
+			     ? UNSPEC_GOTPCREL
+			     : UNSPEC_GOT));
+      op1 = gen_rtx_CONST (Pmode, op1);
+      op1 = gen_const_mem (Pmode, op1);
+      /* This symbol must be referenced via a load from the Global
+	 Offset Table.  */
+      set_mem_alias_set (op1, ix86_GOT_alias_set ());
+      op1 = convert_to_mode (mode, op1, 1);
+      op1 = force_reg (mode, op1);
+      emit_insn (gen_rtx_SET (op0, op1));
+      /* Generate a CLOBBER so that there will be no REG_EQUAL note
+	 on the last insn to prevent cse and fwprop from replacing
+	 a GOT load with a constant.  */
+      rtx tmp = gen_reg_rtx (Pmode);
+      emit_clobber (tmp);
+      return;
     }
   else
     {
diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index b3cf2a3..06a0002 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -149,6 +149,10 @@
 (define_predicate "x86_64_immediate_operand"
   (match_code "const_int,symbol_ref,label_ref,const")
 {
+  /* Load the external function address via the GOT slot to avoid PLT.  */
+  if (ix86_force_load_from_GOT_p (op))
+    return false;
+
   if (!TARGET_64BIT)
     return immediate_operand (op, mode);
 
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-1.c b/gcc/testsuite/gcc.target/i386/pr67400-1.c
new file mode 100644
index 0000000..a875b76
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-1.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern void bar (void);
+
+void *
+foo (void)
+{
+  return &bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-2.c b/gcc/testsuite/gcc.target/i386/pr67400-2.c
new file mode 100644
index 0000000..9f3f4bc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern void bar (void);
+extern void *p;
+
+void
+foo (void)
+{
+  p = &bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-3.c b/gcc/testsuite/gcc.target/i386/pr67400-3.c
new file mode 100644
index 0000000..045974e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-3.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+static void
+bar (void)
+{
+}
+
+void *
+foo (void)
+{
+  return &bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*\\\$bar," } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-4.c b/gcc/testsuite/gcc.target/i386/pr67400-4.c
new file mode 100644
index 0000000..fd373db
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-4.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern void bar (void) __attribute__ ((visibility ("hidden")));
+
+void *
+foo (void)
+{
+  return &bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*\\\$bar," } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-5.c b/gcc/testsuite/gcc.target/i386/pr67400-5.c
new file mode 100644
index 0000000..9bb98dc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-5.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern void foo (void);
+extern void bar (int, int, int, int, int, int, void *);
+
+void
+x (void)
+{
+  bar (1, 2, 3, 4, 5, 6, foo);
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-6.c b/gcc/testsuite/gcc.target/i386/pr67400-6.c
new file mode 100644
index 0000000..b84196a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-6.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern int bar (void);
+
+int
+check (void *p)
+{
+  return p != &bar;
+}
+
+/* { dg-final { scan-assembler "cmp\(l|q\)\[ \t\]*.*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
-- 
2.5.5

^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2016-06-22 22:12 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-06-20 17:05 [PATCH] x86-64: Load external function address via GOT slot H.J. Lu
2016-06-20 19:13 ` Uros Bizjak
2016-06-20 19:19   ` H.J. Lu
2016-06-20 19:27     ` Uros Bizjak
2016-06-20 19:47       ` Richard Sandiford
2016-06-20 20:34         ` H.J. Lu
2016-06-21 12:40         ` H.J. Lu
2016-06-21 18:22           ` Uros Bizjak
2016-06-21 19:51             ` H.J. Lu
2016-06-22 22:12               ` Uros Bizjak

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).