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[dev.ssa] cmd/compile/internal/ssa: fix shift operations

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Convert shift ops to also encode the size of the shift amount.

Change signed right shift from using CMOV to using bit twiddles.
It is a little bit better (5 instructions instead of 4, but fewer
bytes and slightly faster code).  It's also a bit faster than
the 4-instruction branch version, even with a very predictable
branch.  As tested on my machine, YMMV.

Implement OCOM while we are here.

Change-Id: I8ca12dd62fae5d626dc0e6da5d4bbd34fd9640d2
Reviewed-on: https://go-review.googlesource.com/12867
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Keith Randall 2015-07-29 17:07:09 -07:00
parent bdb2d2810d
commit 4b803151ce
7 changed files with 2827 additions and 528 deletions
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12
src/cmd/compile/internal/ssa/shift_test.go
View file

@ -10,17 +10,17 @@ import (
func TestShiftConstAMD64(t *testing.T) {
c := NewConfig("amd64", DummyFrontend{t})
fun := makeConstShiftFunc(c, 18, OpLsh64, TypeUInt64)
fun := makeConstShiftFunc(c, 18, OpLsh64x64, TypeUInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHLQconst: 1, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
fun = makeConstShiftFunc(c, 66, OpLsh64, TypeUInt64)
fun = makeConstShiftFunc(c, 66, OpLsh64x64, TypeUInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHLQconst: 0, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
fun = makeConstShiftFunc(c, 18, OpRsh64U, TypeUInt64)
fun = makeConstShiftFunc(c, 18, OpRsh64Ux64, TypeUInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHRQconst: 1, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
fun = makeConstShiftFunc(c, 66, OpRsh64U, TypeUInt64)
fun = makeConstShiftFunc(c, 66, OpRsh64Ux64, TypeUInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SHRQconst: 0, OpAMD64CMPQconst: 0, OpAMD64ANDQconst: 0})
fun = makeConstShiftFunc(c, 18, OpRsh64, TypeInt64)
fun = makeConstShiftFunc(c, 18, OpRsh64x64, TypeInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SARQconst: 1, OpAMD64CMPQconst: 0})
fun = makeConstShiftFunc(c, 66, OpRsh64, TypeInt64)
fun = makeConstShiftFunc(c, 66, OpRsh64x64, TypeInt64)
checkOpcodeCounts(t, fun.f, map[Op]int{OpAMD64SARQconst: 1, OpAMD64CMPQconst: 0})
}