[dev.ssa] cmd/compile: optimization for && and || expressions
Compiling && and || expressions often leads to control
flow of the following form:
p:
If a goto b else c
b: <- p ...
x = phi(a, ...)
If x goto t else u
Note that if we take the edge p->b, then we are guaranteed
to take the edge b->t also. So in this situation, we might
as well go directly from p to t.
Change-Id: I6974f1e6367119a2ddf2014f9741fdb490edcc12
Reviewed-on: https://go-review.googlesource.com/18910
Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/cmd/compile/internal/ssa/gen/genericOps.go b/src/cmd/compile/internal/ssa/gen/genericOps.go
index 107c145..36dd58c 100644
--- a/src/cmd/compile/internal/ssa/gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/gen/genericOps.go
@@ -245,24 +245,19 @@
// arg0=ptr/int arg1=mem, output=int/ptr
{name: "Convert"},
- // constants. Constant values are stored in the aux field.
- // booleans have a bool aux field, strings have a string aux
- // field, and so on. All integer types store their value
- // in the AuxInt field as an int64 (including int, uint64, etc.).
- // For integer types smaller than 64 bits, only the low-order
- // bits of the AuxInt field matter.
- {name: "ConstBool"},
- {name: "ConstString"},
- {name: "ConstNil", typ: "BytePtr"},
- {name: "Const8"},
- {name: "Const16"},
- {name: "Const32"},
- {name: "Const64"},
- {name: "Const32F"},
- {name: "Const64F"},
- {name: "ConstInterface"}, // nil interface
- {name: "ConstSlice"}, // nil slice
- // TODO: Const32F, ...
+ // constants. Constant values are stored in the aux or
+ // auxint fields.
+ {name: "ConstBool"}, // auxint is 0 for false and 1 for true
+ {name: "ConstString"}, // value is aux.(string)
+ {name: "ConstNil", typ: "BytePtr"}, // nil pointer
+ {name: "Const8"}, // value is low 8 bits of auxint
+ {name: "Const16"}, // value is low 16 bits of auxint
+ {name: "Const32"}, // value is low 32 bits of auxint
+ {name: "Const64"}, // value is auxint
+ {name: "Const32F"}, // value is math.Float64frombits(uint64(auxint))
+ {name: "Const64F"}, // value is math.Float64frombits(uint64(auxint))
+ {name: "ConstInterface"}, // nil interface
+ {name: "ConstSlice"}, // nil slice
// Constant-like things
{name: "InitMem"}, // memory input to the function.
