This is actually two changes. One is to avoid copies when fp values are fed into
a build_vector, without being able to tell from the opcode.
The other is that build_vectors are also marked as only defining FP, since they
produce vector results.
Differential Revision: https://reviews.llvm.org/D97968
https://reviews.llvm.org/D88060
This adds the following combines
1) build_vector formation from insert_vec_elts
2) insert_vec_elts (build_vector) -> build_vector
Unfortunately the leaf SDAG patterns aren't supported yet so we need to do
this manually, but it's not a significant amount of code anyway.
Differential Revision: https://reviews.llvm.org/D87924
This rewrites big parts of the fast register allocator. The basic
strategy of doing block-local allocation hasn't changed but I tweaked
several details:
Track register state on register units instead of physical
registers. This simplifies and speeds up handling of register aliases.
Process basic blocks in reverse order: Definitions are known to end
register livetimes when walking backwards (contrary when walking
forward then uses may or may not be a kill so we need heuristics).
Check register mask operands (calls) instead of conservatively
assuming everything is clobbered. Enhance heuristics to detect
killing uses: In case of a small number of defs/uses check if they are
all in the same basic block and if so the last one is a killing use.
Enhance heuristic for copy-coalescing through hinting: We check the
first k defs of a register for COPYs rather than relying on there just
being a single definition. When testing this on the full llvm
test-suite including SPEC externals I measured:
average 5.1% reduction in code size for X86, 4.9% reduction in code on
aarch64. (ranging between 0% and 20% depending on the test) 0.5%
faster compiletime (some analysis suggests the pass is slightly slower
than before, but we more than make up for it because later passes are
faster with the reduced instruction count)
Also adds a few testcases that were broken without this patch, in
particular bug 47278.
Patch mostly by Matthias Braun
There's more smarts in AArch64ISelLowering that we don't have yet, but this
change incrementally improves some of the more common patterns. I think future
iterations will want to use some combination of PostLegalizerCombiner and the
selector to catch the other cases.
Differential Revision: https://reviews.llvm.org/D82340
Amara Emerson