https://gcc.gnu.org/g:6b4569a3ebdd0df44d87d67a18272ec0b878f2ee
commit r15-9531-g6b4569a3ebdd0df44d87d67a18272ec0b878f2ee
Author: Ard Biesheuvel <a...@kernel.org>
Date: Thu Apr 10 14:26:41 2025 +0200
i386: Enable -mnop-mcount for -fpic with PLTs [PR119386]
-mnop-mcount can be trivially enabled for -fPIC codegen as long as PLTs
are being used, given that the instruction encodings are identical, only
the target may resolve differently depending on how the linker decides
to incorporate the object file.
So relax the option check, and add a test to ensure that 5-byte NOPs are
emitted when -mnop-mcount is being used.
Signed-off-by: Ard Biesheuvel <a...@kernel.org>
gcc/ChangeLog:
PR target/119386
* config/i386/i386-options.cc: Permit -mnop-mcount when
using -fpic with PLTs.
gcc/testsuite/ChangeLog:
PR target/119386
* gcc.target/i386/pr119386-3.c: New test.
Diff:
---
gcc/config/i386/i386-options.cc | 4 ++--
gcc/testsuite/gcc.target/i386/pr119386-3.c | 10 ++++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index a9fac011f3d2..964449fa8cd7 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -2828,8 +2828,8 @@ ix86_option_override_internal (bool main_args_p,
if (flag_nop_mcount)
error ("%<-mnop-mcount%> is not compatible with this target");
#endif
- if (flag_nop_mcount && flag_pic)
- error ("%<-mnop-mcount%> is not implemented for %<-fPIC%>");
+ if (flag_nop_mcount && flag_pic && !flag_plt)
+ error ("%<-mnop-mcount%> is not implemented for %<-fno-plt%>");
/* Accept -msseregparm only if at least SSE support is enabled. */
if (TARGET_SSEREGPARM_P (opts->x_target_flags)
diff --git a/gcc/testsuite/gcc.target/i386/pr119386-3.c
b/gcc/testsuite/gcc.target/i386/pr119386-3.c
new file mode 100644
index 000000000000..287410b951a4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr119386-3.c
@@ -0,0 +1,10 @@
+/* PR target/119386 */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpic -pg -mnop-mcount" } */
+/* { dg-final { scan-assembler ".byte\[ \t\]+0x0f, 0x1f, 0x44, 0x00, 0x00" } }
*/
+
+int
+main ()
+{
+ return 0;
+}
