Constant Pool related information and bugs

http://weblogs.java.net/blog/mlam/archive/2008/03/cvm_jit_constan.html

constant pool bug:
Trace fragments are usually much bigger than block fragments. LLVM ARM JIT fails to put constant pool within the range of load instructions with immediate offset (ranging from 4096 to -4096 bytes), which is referred to as the out-of-range bug.
My first thought is the ARM JIT forget to take out-of-range bug into consideration, but ARMConstantIslandPass does take this into consideration. And, immediately, I found that the source of this bug is the wrongly calculated offset.
Why would this happen in trace mode? Well, this is because I add one intrinsic BLOCKLINK which takes 24 bytes but I didn't update GetInstSizeInBytes() in ARMBaseInstrInfo. So, after I add this information in GetInstSizeInBytes(), the offset is correctly calculated.