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234726 |
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27-Apr-2012 |
dim |
MFC r234502:
After r217375, some startup objects under lib/csu are built in a special way: first they are compiled to assembly, then some sed'ing is done on the assembly, and lastly the assembly is compiled to an object file.
This last step is done using ${CC}, and not ${AS}, because when the compiler is clang, it outputs directives that are too advanced for our old gas. So we use clang's integrated assembler instead. (When the compiler is gcc, it just calls gas, and nothing is different, except one extra fork.)
However, in the .s to .o rules in lib/csu/$ARCH/Makefile, I still passed CFLAGS to the compiler, instead of ACFLAGS, which are specifically for compiling .s files.
In case you are using '-g' for debug info anywhere in your CFLAGS, it causes the .s files to already contain debug information in the assembly itself. In the next step, the .s files are also compiled using '-g', and if the compiler is clang, it complains: "error: input can't have .file dwarf directives when -g is used to generate dwarf debug info for assembly code".
Fix this by using ${ACFLAGS} for compiling the .s files instead.
Reported by: jasone
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217375 |
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13-Jan-2011 |
dim |
Apply a workaround for a binutils issue with the .note.ABI-tag section generated from lib/csu/common/crtbrand.c (which ultimately ends up in executables and shared libraries, via crt1.o, gcrt1.o or Scrt1.o).
For all arches except sparc, gcc emits the section directive for the abitag struct in crtbrand.c with a PROGBITS type. However, newer versions of binutils (after 2.16.90) require the section to be of NOTE type, to guarantee that the .note.ABI-tag section correctly ends up in the first page of the final executable.
Unfortunately, there is no clean way to tell gcc to use another section type, so crtbrand.c (or the C files that include it) must be compiled in multiple steps:
- Compile the .c file to a .s file. - Edit the .s file to change the 'progbits' type to 'note', for the section directive that defines the .note.ABI-tag section. - Compile the .s file to an object file.
These steps are done in the invididual Makefiles for each applicable arch.
Reviewed by: kib
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200038 |
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02-Dec-2009 |
kib |
Properly support -fPIE by linking PIE binaries with specially-built Scrt1.o instead of crt1.o, since the later is built as non-PIC.
Separate i386-elf crt1.c into the pure assembler part and C code, supplying all data extracted by assembler stub as explicit parameters [1]. Hide and localize _start1 symbol used as an interface between asm and C code.
In collaboration with: kan Inspired by: PR i386/127387 [1] Prodded and tested by: rdivacky [1] MFC after: 3 weeks
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