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llvm-project/lld/test/ELF/mips-micro-bad-cross-calls.s

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[MIPS] Handle cross-mode (regular <-> microMIPS) jumps The patch solves two tasks: 1. MIPS ABI allows to mix regular and microMIPS code and perform cross-mode jumps. Linker needs to detect such cases and replace jump/branch instructions by their cross-mode equivalents. 2. Other tools like dunamic linkers need to recognize cases when dynamic table entries, e_entry field of an ELF header etc point to microMIPS symbol. Linker should provide such information. The first task is implemented in the `MIPS<ELFT>::relocateOne()` method. New routine `fixupCrossModeJump` detects ISA mode change, checks and replaces an instruction. The main problem is how to recognize that relocation target is microMIPS symbol. For absolute and section symbols compiler or assembler set the less-significant bit of the symbol's value or sum of the symbol's value and addend. And this bit signals to linker about microMIPS code. For global symbols compiler cannot do the same trick because other tools like, for example, disassembler wants to know an actual position of the symbol. So compiler sets STO_MIPS_MICROMIPS flag in the `st_other` field. In `MIPS<ELFT>::relocateOne()` method we have a symbol's value only and cannot access any symbol's attributes. To pass type of the symbol (regular/microMIPS) to that routine as well as other places where we write a symbol value as-is (.dynamic section, `Elf_Ehdr::e_entry` field etc) we set when necessary a less-significant bit in the `getSymVA` function. Differential revision: https://reviews.llvm.org/D40147 llvm-svn: 354311
2019-02-19 18:36:58 +08:00
# REQUIRES: mips
# Check error message for invalid cross-mode branch instructions.
# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
# RUN: %S/Inputs/mips-dynamic.s -o %t2.o
# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t1.o
[ELF][test] Change -o %t to -o /dev/null if the output is not needed
2020-02-13 13:48:45 +08:00
# RUN: not ld.lld -o /dev/null %t1.o %t2.o 2>&1 | FileCheck %s
[MIPS] Handle cross-mode (regular <-> microMIPS) jumps The patch solves two tasks: 1. MIPS ABI allows to mix regular and microMIPS code and perform cross-mode jumps. Linker needs to detect such cases and replace jump/branch instructions by their cross-mode equivalents. 2. Other tools like dunamic linkers need to recognize cases when dynamic table entries, e_entry field of an ELF header etc point to microMIPS symbol. Linker should provide such information. The first task is implemented in the `MIPS<ELFT>::relocateOne()` method. New routine `fixupCrossModeJump` detects ISA mode change, checks and replaces an instruction. The main problem is how to recognize that relocation target is microMIPS symbol. For absolute and section symbols compiler or assembler set the less-significant bit of the symbol's value or sum of the symbol's value and addend. And this bit signals to linker about microMIPS code. For global symbols compiler cannot do the same trick because other tools like, for example, disassembler wants to know an actual position of the symbol. So compiler sets STO_MIPS_MICROMIPS flag in the `st_other` field. In `MIPS<ELFT>::relocateOne()` method we have a symbol's value only and cannot access any symbol's attributes. To pass type of the symbol (regular/microMIPS) to that routine as well as other places where we write a symbol value as-is (.dynamic section, `Elf_Ehdr::e_entry` field etc) we set when necessary a less-significant bit in the `getSymVA` function. Differential revision: https://reviews.llvm.org/D40147 llvm-svn: 354311
2019-02-19 18:36:58 +08:00
# CHECK: (.text+0x0): unsupported jump/branch instruction between ISA modes referenced by R_MICROMIPS_PC10_S1 relocation
.text
.set micromips
.global __start
__start:
b16 foo0