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wasmtime/cranelift/filetests/preopt/simplify.cton
Dan Gohman 6606b88136 Optimize immediates and compare and branch sequences (#286)
* Add a pre-opt optimization to change constants into immediates.

This converts 'iadd' + 'iconst' into 'iadd_imm', and so on.

* Optimize away redundant `bint` instructions.

Cretonne has a concept of "Testable" values, which can be either boolean
or integer. When the an instruction needing a "Testable" value receives
the result of a `bint`, converting boolean to integer, eliminate the
`bint`, as it's redundant.

* Postopt: Optimize using CPU flags.

This introduces a post-legalization optimization pass which converts
compare+branch sequences to use flags values on CPUs which support it.

* Define a form of x86's `urm` that doesn't clobber FLAGS.

movzbl/movsbl/etc. don't clobber FLAGS; define a form of the `urm`
recipe that represents this.

* Implement a DCE pass.

This pass deletes instructions with no side effects and no results that
are used.

* Clarify ambiguity about "32-bit" and "64-bit" in comments.

* Add x86 encodings for icmp_imm.

* Add a testcase for postopt CPU flags optimization.

This covers the basic functionality of transforming compare+branch
sequences to use CPU flags.

* Pattern-match irsub_imm in preopt.
2018-03-30 12:30:07 -07:00

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test preopt
isa intel
function %iadd_imm(i32) -> i32 {
ebb0(v0: i32):
v1 = iconst.i32 2
v2 = iadd v0, v1
return v2
}
; sameln: function %iadd_imm
; nextln: ebb0(v0: i32):
; nextln: v1 = iconst.i32 2
; nextln: v2 = iadd_imm v0, 2
; nextln: return v2
; nextln: }
function %isub_imm(i32) -> i32 {
ebb0(v0: i32):
v1 = iconst.i32 2
v2 = isub v0, v1
return v2
}
; sameln: function %isub_imm
; nextln: ebb0(v0: i32):
; nextln: v1 = iconst.i32 2
; nextln: v2 = iadd_imm v0, -2
; nextln: return v2
; nextln: }
function %icmp_imm(i32) -> i32 {
ebb0(v0: i32):
v1 = iconst.i32 2
v2 = icmp slt v0, v1
v3 = bint.i32 v2
return v3
}
; sameln: function %icmp_imm
; nextln: ebb0(v0: i32):
; nextln: v1 = iconst.i32 2
; nextln: v2 = icmp_imm slt v0, 2
; nextln: v3 = bint.i32 v2
; nextln: return v3
; nextln: }
function %brz_bint(i32) {
ebb0(v0: i32):
v3 = icmp_imm slt v0, 0
v1 = bint.i32 v3
v2 = select v1, v1, v1
trapz v1, user0
brz v1, ebb1
jump ebb2
ebb1:
return
ebb2:
return
}
; sameln: function %brz_bint
; nextln: (v0: i32):
; nextln: v3 = icmp_imm slt v0, 0
; nextln: v1 = bint.i32 v3
; nextln: v2 = select v3, v1, v1
; nextln: trapz v3, user0
; nextln: brz v3, ebb1
; nextln: jump ebb2
function %irsub_imm(i32) -> i32 {
ebb0(v0: i32):
v1 = iconst.i32 2
v2 = isub v1, v0
return v2
}
; sameln: function %irsub_imm
; nextln: ebb0(v0: i32):
; nextln: v1 = iconst.i32 2
; nextln: v2 = irsub_imm v1, 2
; nextln: return v2
; nextln: }