The usage of FP Load and Test instructions as a comparison against zero
with the assumption that the dest reg will always reflect the source reg is
actually incorrect: Unfortunately, a SNaN will be converted to a QNaN, so the
instruction may actually change the value as opposed to being a pure register
move with a test.
This patch
- changes instruction selection to always emit FP LT with a scratch def
reg, which will typically be allocated to the same reg if dead.
- Removes the conversions into FP LT in SystemZElimcompare.
D150312 added a TODO:
TODO: consider renaming the field `StartAtCycle` and `Cycles` to
`AcquireAtCycle` and `ReleaseAtCycle` respectively, to stress the
fact that resource allocation is now represented as an interval,
relatively to the issue cycle of the instruction.
This patch implements that TODO. This naming clarifies how to use these
fields in the scheduler. In addition it was confusing that `StartAtCycle` was
singular but `Cycles` was plural. This renaming fixes this inconsistency.
This commit as previously reverted since it missed renaming that came
down after rebasing. This version of the commit fixes those problems.
Differential Revision: https://reviews.llvm.org/D158568
D150312 added a TODO:
TODO: consider renaming the field `StartAtCycle` and `Cycles` to
`AcquireAtCycle` and `ReleaseAtCycle` respectively, to stress the
fact that resource allocation is now represented as an interval,
relatively to the issue cycle of the instruction.
This patch implements that TODO. This naming clarifies how to use these
fields in the scheduler. In addition it was confusing that `StartAtCycle` was
singular but `Cycles` was plural. This renaming fixes this inconsistency.
This commit as previously reverted since it missed renaming that came
down after rebasing. This version of the commit fixes those problems.
Differential Revision: https://reviews.llvm.org/D158568
D150312 added a TODO:
TODO: consider renaming the field `StartAtCycle` and `Cycles` to
`AcquireAtCycle` and `ReleaseAtCycle` respectively, to stress the
fact that resource allocation is now represented as an interval,
relatively to the issue cycle of the instruction.
This patch implements that TODO. This naming clarifies how to use these
fields in the scheduler. In addition it was confusing that `StartAtCycle` was
singular but `Cycles` was plural. This renaming fixes this inconsistency.
Differential Revision: https://reviews.llvm.org/D158568
