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authorKartik Agaram <vc@akkartik.com>2020-03-07 17:32:39 -0800
committerKartik Agaram <vc@akkartik.com>2020-03-07 17:40:45 -0800
commit3cf03158599472b1f6713192d9fa2b120f9f209b (patch)
tree4982565ff8b289847c1c263f4d9aeb3c2360b98b /apps/calls
parent9ee4b34e068550462d440ebc522c7e8ad0c0f2e6 (diff)
downloadmu-3cf03158599472b1f6713192d9fa2b120f9f209b.tar.gz
6094 - new 'compute-offset' instruction
If indexing into a type with power-of-2-sized elements we can access them
in one instruction:

  x/reg1: (addr int) <- index A/reg2: (addr array int), idx/reg3: int

This translates to a single instruction because x86 instructions support
an addressing mode with left-shifts.

For non-powers-of-2, however, we need a multiply. To keep things type-safe,
it is performed like this:

  x/reg1: (offset T) <- compute-offset A: (addr array T), idx: int
  y/reg2: (addr T) <- index A, x

An offset is just an int that is guaranteed to be a multiple of size-of(T).
Offsets can only be used in index instructions, and the types will eventually
be required to line up.

In the process, I have to expand Input-size because mu.subx is growing
big.
Diffstat (limited to 'apps/calls')
-rwxr-xr-xapps/callsbin47207 -> 47207 bytes
1 files changed, 0 insertions, 0 deletions
diff --git a/apps/calls b/apps/calls
index c7e2b758..f22a1b2c 100755
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