Block Load And Store Instructions (Vis I) - Fujitsu SPARC JPS1 Implementation Supplement Manual

A.4

Block Load and Store Instructions (VIS I)

The following notes summarize behavior of block load/store instructions in
SPARC64 V.
1. Block load and store operations are not atomic, in that they are internally
decomposed into eight independent, 8-byte load/store operations in SPARC64 V.
Each load/store is always issued and performed in the RMO memory model and
obeys all prior MEMBAR and atomic instruction-imposed ordering constraints.
2. Block load/store instructions are out of the scope of V9 memory models, meaning
that self-consistency of memory reference instruction is not always maintained if
block load/store instructions are involved in the execution flow. The following
table describes the implemented ordering constraints for block load/store
instructions with respect to the other memory reference instructions with an
operand address conflict in SPARC64 V:
Program Order for conflicting bld/bst/ld/st
first
store
store
load
load
blockstore
blockstore
blockstore
blockstore
blockload
blockload
blockload
blockload
To maintain the memory ordering even for the memory address conflicts, MEMBAR
instructions shall be inserted into appropriate location in the program.
Although self-consistency with respect to the block load/store and the other
memory reference instructions is not maintained in some cases, register conflicts
between the other instructions and block load/store instructions are maintained
in SPARC64 V. The read-after-write, write-after-read, and write-after-write
obstructions between a block load/store instruction and the other arithmetic
instructions are detected and handled appropriately.
3. Block load instruction operate on the cache if the operand is present.
Release 1.0, 1 July 2002
next
blockstore
blockload
blockstore
blockload
store
load
blockstore
blockload
store
load
blockstore
blockload
F. Chapter A Instruction Definitions: SPARC64 V Extensions
Ordered/
Out-of-Order
Ordered
Ordered
Ordered
Ordered
Out-of-Order
Out-of-Order
Out-of-Order
Out-of-Order
Ordered
Ordered
Ordered
Ordered
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