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Sources Bugzilla – Full Text Bug Listing |
| Summary: | "ld -r" doesn't work with mixed IR/non-IR objects | ||
|---|---|---|---|
| Product: | binutils | Reporter: | H.J. Lu <hjl.tools> |
| Component: | ld | Assignee: | H.J. Lu <hjl.tools> |
| Status: | NEW --- | ||
| Severity: | normal | CC: | ian |
| Priority: | P2 | ||
| Version: | 2.22 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
One approach -- We generate a prog.o that contains an object that is the relocation of real foo.o and main.o (used if prog.o is linked without IR support), that also contains IR for main.o, and within the IR the object code for main.o. So the interesting case is when the relocatable object is again compiled in such a way that the IR is read out from prog.o. The Intel compiler will take the IR from prog.o, and compile it with any other IR present in archives or other objects (none in this particular case), and will create a real object from the IR, this is then added to a list of objects that the driver will pass to the linker along with the object code for main.o which the compiler extracts to a new temporary object that is added to the list of objects. -- The proposal is at http://www.kernel.org/pub/linux/devel/gcc/lto/mixed-IR/mixed-IR.pdf It is implemented on hjl/lto-mixed branch at http://git.kernel.org/?p=devel/binutils/hjl/x86.git;a=summary ld.ian (gold with patch <http://sourceware.org/ml/binutils/2011-01/msg00270.html>) silently uses non-IR part of prog.o (In reply to comment #3) > ld.ian (gold with patch > <http://sourceware.org/ml/binutils/2011-01/msg00270.html>) silently uses non-IR > part of prog.o What does gold generate for /usr/gcc-4.6/bin/gcc -B./ -c -O -flto -fuse-linker-plugin main.c -o main.o /usr/gcc-4.6/bin/gcc -B./ -c -O foo.c -o foo.o ./ld -r -o prog.o main.o foo.o Does prog.o contain both IR and non-IR sections? > Does prog.o contain both IR and non-IR sections?
No. I think a new bug report should be opened for gold.
When I use ld.bfd (or ld.hjl) for partial link step and ld.ian for final link,
everything works.
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[hjl@gnu-6 pr-1]$ cat foo.c #include <stdio.h> void foo(void) { printf ("hello foo\n"); } [hjl@gnu-6 pr-1]$ cat main.c extern void foo(void); int main(void) { foo(); return 0; } [hjl@gnu-6 pr-1]$ make /usr/gcc-4.6/bin/gcc -B./ -c -O -flto -fuse-linker-plugin main.c -o main.o /usr/gcc-4.6/bin/gcc -B./ -c -O foo.c -o foo.o ./ld -r -o prog.o main.o foo.o /usr/gcc-4.6/bin/gcc -B./ -flto -fuse-linker-plugin prog.o -o prog /tmp/ccAWLRVh.ltrans0.ltrans.o: In function `main': ccAWLRVh.ltrans0.o:(.text.startup+0x5): undefined reference to `foo' collect2: ld returned 1 exit status make: *** [prog] Error 1 [hjl@gnu-6 pr-1]$