[gcc r13-4166] nvptx: In 'STARTFILE_SPEC', fix 'crt0.o' for '-mmainkernel'

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:dda43e1ef0c9f6c32ad022d3a08ce7651e42a129

commit r13-4166-gdda43e1ef0c9f6c32ad022d3a08ce7651e42a129
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Fri Nov 18 23:57:52 2022 +0100

    nvptx: In 'STARTFILE_SPEC', fix 'crt0.o' for '-mmainkernel'
    
    A recent nvptx-tools change: commit 886a95faf66bf66a82fc0fe7d2a9fd9e9fec2820
    "ld: Don't search for input files in '-L'directories" (of
    <https://github.com/MentorEmbedded/nvptx-tools/pull/38>
    "Match standard 'ld' "search" behavior") in GCC/nvptx target testing
    generally causes linking to fail with:
    
        error opening crt0.o
        collect2: error: ld returned 1 exit status
        compiler exited with status 1
    
    Indeed per GCC '-v' output, there is an undecorated 'crt0.o' on the linker
    ('collect2') command line:
    
         [...]/build-gcc/./gcc/collect2 -o [...] crt0.o [...]
    
    This is due to:
    
        gcc/config/nvptx/nvptx.h:#define STARTFILE_SPEC "%{mmainkernel:crt0.o}"
    
    ..., and the fix, as used by numerous other GCC targets, is to instead use
    'crt0.o%s'; for '%s' means, per 'gcc/gcc.cc', "The Specs Language":
    
         %s     current argument is the name of a library or startup file of some sort.
                Search for that file in a standard list of directories
                and substitute the full name found.
    
    With that, we get the expected path to 'crt0.o'.
    
            gcc/
            * config/nvptx/nvptx.h (STARTFILE_SPEC): Fix 'crt0.o' for
            '-mmainkernel'.

Diff:
---
 gcc/config/nvptx/nvptx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
index 0afc83b10a3..dc676dcb5fc 100644
--- a/gcc/config/nvptx/nvptx.h
+++ b/gcc/config/nvptx/nvptx.h
@@ -35,7 +35,7 @@
    '../../gcc.cc:asm_options', 'HAVE_GNU_AS'.  */
 #define ASM_SPEC "%{v}"
 
-#define STARTFILE_SPEC "%{mmainkernel:crt0.o}"
+#define STARTFILE_SPEC "%{mmainkernel:crt0.o%s}"
 
 #define TARGET_CPU_CPP_BUILTINS() nvptx_cpu_cpp_builtins ()