nvptx: In 'STARTFILE_SPEC', fix 'crt0.o' for '-mmainkernel' (was: [MentorEmbedded/nvptx-tools] Match standard 'ld' "search" behavior (PR #38))

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

Re
<https://github.com/MentorEmbedded/nvptx-tools/pull/38#issuecomment-1320419585>:

On 2022-11-18T11:05:23-0800, I wrote:
> Actually, in GCC/nvptx target testing, this #38's commit 886a95faf66bf66a82fc0fe7d2a9fd9e9fec2820 "ld: Don't search for input files in '-L'directories" is generally causing linking to fail with:
>
> ```
> error opening crt0.o
> collect2: error: ld returned 1 exit status
> compiler exited with status 1
> ```
>
> I'm investigating.

OK to push the attached
GCC "nvptx: In 'STARTFILE_SPEC', fix 'crt0.o' for '-mmainkernel'" to all
active GCC branches?  (... instead of having to restore this "blunder"
(do "search for input files in '-L'directories") in nvptx-tools...)


Grüße
 Thomas


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From 85ddd99017968e8aa45342645be9642e63bcc5bb Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Fri, 18 Nov 2022 23:57:52 +0100
Subject: [PATCH] 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'.
---
 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 ()
 
-- 
2.25.1