On Wed, Mar 17, 2021 at 6:14 AM Uros Bizjak <ubiz...@gmail.com> wrote:
>
> On Wed, Mar 17, 2021 at 1:45 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> >
> > On Wed, Mar 17, 2021 at 12:40 AM Uros Bizjak <ubiz...@gmail.com> wrote:
> > >
> > > On Tue, Mar 16, 2021 at 4:59 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > > >
> > > > On Sun, Mar 14, 2021 at 1:31 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > > > >
> > > > > On Sun, Mar 14, 2021 at 12:43 PM Uros Bizjak <ubiz...@gmail.com>
> > > > > wrote:
> > > > > >
> > > > > > On Sun, Mar 14, 2021 at 8:14 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > > > > > > > > Done. Here is the updated patch. Tested on Linux/x86-64.
> > > > > > > > > OK for master?
> > > > > > > >
> > > > > > > > I don't understand the purpose of the current_output_insn check
> > > > > > > > and I
> > > > > > > > don't know if the usage of current_output_insn is correct. The
> > > > > > > > comments are not helpful either, and no other target uses this
> > > > > > > > variable in the way you propose. Can you please elaborate the
> > > > > > > > reason
> > > > > > > > and the purpose of the check a bit more?
> > > > > > > >
> > > > > > > > Uros.
> > > > > > >
> > > > > > > Originally, ix86_force_load_from_GOT_p is only for non-PIC. My
> > > > > > > patch extended
> > > > > > > it to inline assembly statements where current_output_insn ==
> > > > > > > NULL and PIC is
> > > > > > > allowed in 64-bit.
> > > > > >
> > > > > > I can see this from the patch, but this explanation didn't answer
> > > > > > my question.
> > > > > >
> > > > >
> > > > > The purpose of current_output_insn == NULL is to allow PIC for inline
> > > > > asm statements in 64-bit mode. Is there a better way to check if
> > > > > ix86_print_operand () is called on inline asm statements?
> > > > >
> > > >
> > > > Here is the v4 patch to check this_is_asm_operands for inline
> > > > asm statements. OK for master?
> > >
> > > -ENOPATCH.
> > >
> > > Uros.
> >
> > Here is the patch.
>
> -/* True if operand X should be loaded from GOT. */
> +/* True if the function symbol operand X should be loaded from GOT.
>
> vertical space here
Fixed.
> + NB: For inline assembly statement, allow PIC/non-PIC in 64-bit mode
> + and in 32-bit mode, only non-PIC is allowed since we don't have
> + PIC register at call site. Otherwise, only PIC is allowed. */
> NB: in 32-bit mode, only non-PIC is allowed in inline assembly
> statements, since a PIC register could not be available at the call site.
Fixed.
> bool
>
> + /* For inline assembly statement, load function address
> + from GOT with 'P' operand modifier to avoid PLT.
> + NB: This works only with call or jmp. */
>
> Please remove this NB, you can't expect from users to read source
> code. This should be in the documentation.
Fixed.
> LGTM otherwise.
This is the patch I am checking in.
Thanks.
--
H.J.
From 3e0bb7c313f1c13b5a01af9ef57c6d0d766085fd Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.to...@gmail.com>
Date: Thu, 11 Mar 2021 06:48:24 -0800
Subject: [PATCH v5] x86: Update 'P' operand modifier for -fno-plt
Update 'P' operand modifier for -fno-plt to support inline assembly
statements. In 64-bit, we can always load function address with
@GOTPCREL. In 32-bit, we load function address with @GOT only for
non-PIC since PIC register may not be available at call site.
gcc/
PR target/99504
* config/i386/i386.c (ix86_force_load_from_GOT_p): Support
inline assembly statements.
(ix86_print_operand): Update 'P' handling for -fno-plt.
gcc/testsuite/
PR target/99504
* gcc.target/i386/pr99530-1.c: New test.
* gcc.target/i386/pr99530-2.c: Likewise.
* gcc.target/i386/pr99530-3.c: Likewise.
* gcc.target/i386/pr99530-4.c: Likewise.
* gcc.target/i386/pr99530-5.c: Likewise.
* gcc.target/i386/pr99530-6.c: Likewise.
---
gcc/config/i386/i386.c | 32 +++++++++++++++++++----
gcc/testsuite/gcc.target/i386/pr99530-1.c | 11 ++++++++
gcc/testsuite/gcc.target/i386/pr99530-2.c | 11 ++++++++
gcc/testsuite/gcc.target/i386/pr99530-3.c | 11 ++++++++
gcc/testsuite/gcc.target/i386/pr99530-4.c | 11 ++++++++
gcc/testsuite/gcc.target/i386/pr99530-5.c | 11 ++++++++
gcc/testsuite/gcc.target/i386/pr99530-6.c | 11 ++++++++
7 files changed, 93 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-2.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-4.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-5.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-6.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 2603333f87b..540d4f44517 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -10265,15 +10265,20 @@ darwin_local_data_pic (rtx disp)
&& XINT (disp, 1) == UNSPEC_MACHOPIC_OFFSET);
}
-/* True if operand X should be loaded from GOT. */
+/* True if the function symbol operand X should be loaded from GOT.
+
+ NB: In 32-bit mode, only non-PIC is allowed in inline assembly
+ statements, since a PIC register could not be available at the
+ call site. */
bool
ix86_force_load_from_GOT_p (rtx x)
{
- return ((TARGET_64BIT || HAVE_AS_IX86_GOT32X)
+ return ((TARGET_64BIT || (!flag_pic && HAVE_AS_IX86_GOT32X))
&& !TARGET_PECOFF && !TARGET_MACHO
- && !flag_pic
+ && (!flag_pic || this_is_asm_operands)
&& ix86_cmodel != CM_LARGE
+ && ix86_cmodel != CM_LARGE_PIC
&& GET_CODE (x) == SYMBOL_REF
&& SYMBOL_REF_FUNCTION_P (x)
&& (!flag_plt
@@ -12701,7 +12706,8 @@ print_reg (rtx x, int code, FILE *file)
y -- print "st(0)" instead of "st" as a register.
d -- print duplicated register operand for AVX instruction.
D -- print condition for SSE cmp instruction.
- P -- if PIC, print an @PLT suffix.
+ P -- if PIC, print an @PLT suffix. For -fno-plt, load function
+ address from GOT.
p -- print raw symbol name.
X -- don't print any sort of PIC '@' suffix for a symbol.
& -- print some in-use local-dynamic symbol name.
@@ -13445,7 +13451,23 @@ ix86_print_operand (FILE *file, rtx x, int code)
x = const0_rtx;
}
- if (code != 'P' && code != 'p')
+ if (code == 'P')
+ {
+ if (ix86_force_load_from_GOT_p (x))
+ {
+ /* For inline assembly statement, load function address
+ from GOT with 'P' operand modifier to avoid PLT. */
+ x = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, x),
+ (TARGET_64BIT
+ ? UNSPEC_GOTPCREL
+ : UNSPEC_GOT));
+ x = gen_rtx_CONST (Pmode, x);
+ x = gen_const_mem (Pmode, x);
+ ix86_print_operand (file, x, 'A');
+ return;
+ }
+ }
+ else if (code != 'p')
{
if (CONST_INT_P (x))
{
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-1.c b/gcc/testsuite/gcc.target/i386/pr99530-1.c
new file mode 100644
index 00000000000..080d7cc9399
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-O2 -fpic -mcmodel=large -fno-plt" } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" } } */
+
+extern void foo (void);
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-2.c b/gcc/testsuite/gcc.target/i386/pr99530-2.c
new file mode 100644
index 00000000000..9808957d624
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-O2 -fno-pic -mcmodel=large -fno-plt" } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" } } */
+
+extern void foo (void);
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-3.c b/gcc/testsuite/gcc.target/i386/pr99530-3.c
new file mode 100644
index 00000000000..22fe81b25f2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-3.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOT" { target { ia32 && got32x_reloc } } } } */
+
+extern void foo (void);
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-4.c b/gcc/testsuite/gcc.target/i386/pr99530-4.c
new file mode 100644
index 00000000000..aba0b5d7892
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-options "-O2 -fpic -fno-plt" } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target { ia32 } } } } */
+
+extern void foo (void);
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-5.c b/gcc/testsuite/gcc.target/i386/pr99530-5.c
new file mode 100644
index 00000000000..02c5799d273
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-5.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-options "-O2 -fno-pic" } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOT" { target { ia32 && got32x_reloc } } } } */
+
+extern void foo (void) __attribute__ ((noplt));
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr99530-6.c b/gcc/testsuite/gcc.target/i386/pr99530-6.c
new file mode 100644
index 00000000000..0dfdd3752f7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99530-6.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
+/* { dg-options "-O2 -fpic" } */
+/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target { ia32 } } } } */
+
+extern void foo (void) __attribute__ ((noplt));
+void
+bar (void)
+{
+ asm ("call %P0" : : "X" (foo));
+}
--
2.30.2
