From 6b4569a3ebdd0df44d87d67a18272ec0b878f2ee Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 10 Apr 2025 14:26:41 +0200 Subject: [PATCH] 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 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. --- gcc/config/i386/i386-options.cc | 4 ++-- gcc/testsuite/gcc.target/i386/pr119386-3.c | 10 ++++++++++ 2 files changed, 12 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr119386-3.c diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc index a9fac011f3d..964449fa8cd 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 00000000000..287410b951a --- /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; +} -- 2.47.2