[LLVMdev] [PATCH] Fix arm sbfx/ubfx generation

[Evan Cheng]

Thanks. I've applied your patch after tweaking the test.

Evan

On Oct 20, 2009, at 8:21 PM, David Conrad wrote:

> On Oct 20, 2009, at 10:27 PM, David Conrad wrote:
> 
>> Hi,
>> 
>> Currently llvm can generate an invalid sbfx/ubfx op, for instance when compiling encoder/analyse.c in x264 (I'll reduce this to a test case if needed):
> 
> Well I just read the dev policy and saw that this was required, so test case attached. It'll break if llvm starts emitting the lsl r0, r0, #3 / asr r0, r0, #1 variants for shifts, not sure how to handle that.
> 
>> LSB isn't checked to ensure it's non-negative. In addition, LSB + Width cannot be >32, since it reduces to (Srl_imm - Shl_imm) + (32 - Srl_imm) == 32 - Shl_imm, and it was already assert()ed that 0 < Shl_imm < 32. So that check is just replaced by if (LSB < 0)
> 
> 
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