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lcpi0_1
2016 May 06
3
Unnecessary spill/fill issue
...utes a series of constant vectors at compile time.
Each vector has a single use. In the final asm, I see a series of spills at
the top of the function of all the constant vectors immediately to stack,
then each use references the stack pointer directly:
Lots of these at top of function:
movabsq $.LCPI0_212, %rbx
vmovaps (%rbx), %ymm0
vmovaps %ymm0, 2816(%rsp) # 32-byte Spill
Later on, each use references the stack pointer:
vpaddd 2816(%rsp), %ymm4, %ymm1 # 32-byte Folded Reload
It seems the spill to stack is unnecessary. In one particularly bad kernel,
I have 128 8-wide constant vectors, and...