[LLVMdev] [Patch] Let MC/ELF generate Thumb/Thumb-2 are properly

[Koan-Sin Tan]

Hi,

We are trying to use clang as a drop-in replacement for the gcc come with
Android NDK. I found that MC/ELF doesn't not handle Thumb functions properly,
e.g., bit 0 of the function name in the .symtab is not set to 1, and some thumb
instructions are not generated correctly, e.g., the addresses for tBL/tBLX are
not calculated right.

With that attached patch, we can compile and run some (not all) Android
NDK samples without problem.

The attached initial patch
1. sets bit 0 of the function address of thumb function in .symtab
   ("T is 1 if the target symbol S has type STT_FUNC and the
   symbol addresses a Thumb instruction ;it is 0 otherwise."
   from "ELF for the ARM Architecture" 4.7.1.2)

2. fixes target address tBL and tBLX
3. sets relocation type of tBL/tBLX to R_ARM_THM_CALL
    (4.7.1.6)
4. adds some attributes to attribute section when cpu is "xscale"
   (this is what used in Android NDK, when architecture is ARMv5)

--
// koan-sin tan
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