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cd4b68bee9
priority function. Instead, just iterate over the AllNodes list, which is already in topological order. This eliminates a fair amount of bookkeeping, and speeds up the isel phase by about 15% on many testcases. The impact on most targets is that AddToISelQueue calls can be simply removed. In the x86 target, there are two additional notable changes. The rule-bending AND+SHIFT optimization in MatchAddress that creates new pre-isel nodes during isel is now a little more verbose, but more robust. Instead of either creating an invalid DAG or creating an invalid topological sort, as it has historically done, it can now just insert the new nodes into the node list at a position where they will be consistent with the topological ordering. Also, the address-matching code has logic that checked to see if a node was "already selected". However, when a node is selected, it has all its uses taken away via ReplaceAllUsesWith or equivalent, so it won't recieve any further visits from MatchAddress. This code is now removed. llvm-svn: 58748
To-do
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* Keep the address of the constant pool in a register instead of forming its
address all of the time.
* We can fold small constant offsets into the %hi/%lo references to constant
pool addresses as well.
* When in V9 mode, register allocate %icc[0-3].
* Add support for isel'ing UMUL_LOHI instead of marking it as Expand.
* Emit the 'Branch on Integer Register with Prediction' instructions. It's
not clear how to write a pattern for this though:
float %t1(int %a, int* %p) {
%C = seteq int %a, 0
br bool %C, label %T, label %F
T:
store int 123, int* %p
br label %F
F:
ret float undef
}
codegens to this:
t1:
save -96, %o6, %o6
1) subcc %i0, 0, %l0
1) bne .LBBt1_2 ! F
nop
.LBBt1_1: ! T
or %g0, 123, %l0
st %l0, [%i1]
.LBBt1_2: ! F
restore %g0, %g0, %g0
retl
nop
1) should be replaced with a brz in V9 mode.
* Same as above, but emit conditional move on register zero (p192) in V9
mode. Testcase:
int %t1(int %a, int %b) {
%C = seteq int %a, 0
%D = select bool %C, int %a, int %b
ret int %D
}
* Emit MULX/[SU]DIVX instructions in V9 mode instead of fiddling
with the Y register, if they are faster.
* Codegen bswap(load)/store(bswap) -> load/store ASI
* Implement frame pointer elimination, e.g. eliminate save/restore for
leaf fns.
* Fill delay slots