Commit Graph

4 Commits

Author SHA1 Message Date
Geoff Berry a5335647d5 [AArch64] Combine callee-save and local stack SP adjustment instructions.
Summary:
If a function needs to allocate both callee-save stack memory and local
stack memory, we currently decrement/increment the SP in two steps:
first for the callee-save area, and then for the local stack area.  This
changes the code to allocate them both at once at the very beginning/end
of the function.  This has two benefits:

1) there is one fewer sub/add micro-op in the prologue/epilogue

2) the stack adjustment instructions act as a scheduling barrier, so
moving them to the very beginning/end of the function increases post-RA
scheduler's ability to move instructions (that only depend on argument
registers) before any of the callee-save stores

This change can cause an increase in instructions if the original local
stack SP decrement could be folded into the first store to the stack.
This occurs when the first local stack store is to stack offset 0.  In
this case we are trading off one more sub instruction for one fewer sub
micro-op (along with benefits (2) and (3) above).

Reviewers: t.p.northover

Subscribers: aemerson, rengolin, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D18619

llvm-svn: 268746
2016-05-06 16:34:59 +00:00
Chad Rosier 11c825f7db [AArch64] Remove an unnecessary restriction on pre-index instructions.
Previously, the index was constrained to the size of the memory operation for
no apparent reason.  This change removes that constraint so that we can form
pre-index instructions with any valid offset.

llvm-svn: 248931
2015-09-30 19:44:40 +00:00
Tim Northover 293d414380 AArch64: fix wrong-endian parameter passing.
The blocked arguments code didn't take account of the hacks needed to support
it.

llvm-svn: 223247
2014-12-03 17:49:26 +00:00
Amara Emerson 82da7d07a1 [AArch64] Narrow arguments passed in wrong position on the stack in
big-endian mode.

Patch by Asiri Rathnayake.

Differential Revision: http://reviews.llvm.org/D4922

llvm-svn: 215716
2014-08-15 14:29:57 +00:00