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* [gcc r12-1318] i386: Do not emit segment overrides for %p and %P [PR100936]
@ 2021-06-09 7:46 Uros Bizjak
0 siblings, 0 replies; only message in thread
From: Uros Bizjak @ 2021-06-09 7:46 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:267dbd42f42c52a515f49c0875d296a9cf5988fe
commit r12-1318-g267dbd42f42c52a515f49c0875d296a9cf5988fe
Author: Uros Bizjak <ubizjak@gmail.com>
Date: Wed Jun 9 09:46:00 2021 +0200
i386: Do not emit segment overrides for %p and %P [PR100936]
Using %p to move the address of a symbol using LEA:
asm ("lea %p1, %0" : "=r"(addr) : "m"(var));
emits assembler warning when VAR is declared in a non-generic address space:
Warning: segment override on `lea' is ineffectual
The problem is with %p operand modifier, which should emit raw symbol name:
p -- print raw symbol name.
Similar problem exists with %P modifier, trying to CALL or JMP to an
overridden symbol,e.g:
call %gs:zzz
jmp %gs:zzz
emits assembler warning:
Warning: skipping prefixes on `call'
Warning: skipping prefixes on `jmp'
Ensure that %p and %P never emit segment overrides.
2021-06-08 Uroš Bizjak <ubizjak@gmail.com>
gcc/
PR target/100936
* config/i386/i386.c (print_operand_address_as): Rename "no_rip"
argument to "raw". Do not emit segment overrides when "raw" is true.
gcc/testsuite/
PR target/100936
* gcc.target/i386/pr100936.c: New test.
Diff:
---
gcc/config/i386/i386.c | 6 +++---
gcc/testsuite/gcc.target/i386/pr100936.c | 34 ++++++++++++++++++++++++++++++++
2 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index b0d19a61a76..05b8dc806cd 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -13531,7 +13531,7 @@ ix86_print_operand_punct_valid_p (unsigned char code)
static void
ix86_print_operand_address_as (FILE *file, rtx addr,
- addr_space_t as, bool no_rip)
+ addr_space_t as, bool raw)
{
struct ix86_address parts;
rtx base, index, disp;
@@ -13570,7 +13570,7 @@ ix86_print_operand_address_as (FILE *file, rtx addr,
else
gcc_assert (ADDR_SPACE_GENERIC_P (parts.seg));
- if (!ADDR_SPACE_GENERIC_P (as))
+ if (!ADDR_SPACE_GENERIC_P (as) && !raw)
{
if (ASSEMBLER_DIALECT == ASM_ATT)
putc ('%', file);
@@ -13589,7 +13589,7 @@ ix86_print_operand_address_as (FILE *file, rtx addr,
}
/* Use one byte shorter RIP relative addressing for 64bit mode. */
- if (TARGET_64BIT && !base && !index && !no_rip)
+ if (TARGET_64BIT && !base && !index && !raw)
{
rtx symbol = disp;
diff --git a/gcc/testsuite/gcc.target/i386/pr100936.c b/gcc/testsuite/gcc.target/i386/pr100936.c
new file mode 100644
index 00000000000..c076cbb2405
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr100936.c
@@ -0,0 +1,34 @@
+/* PR target/100936 */
+/* { dg-do assemble } */
+/* { dg-options "-O2" } */
+
+__seg_gs int var;
+
+static int
+*foo (void)
+{
+ int *addr;
+
+ asm ("lea %p1, %0" : "=r"(addr) : "m"(var));
+
+ return addr;
+}
+
+static int
+bar (int *addr)
+{
+ int val;
+
+ asm ("mov %%gs:%1, %0" : "=r"(val) : "m"(*addr));
+
+ return val;
+}
+
+int
+baz (void)
+{
+ int *addr = foo();
+ int val = bar (addr);
+
+ return val;
+}
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