cmd/compile/internal/ssa: inline memmove with known size
Replace calls to memmove with known (constant) size, with OpMove.
Do it only if it is safe from aliasing point of view.
Helps with code like this:
append(buf,"const str"...)
In strconv this provides nice benefit:
Quote-6 731ns ± 2% 647ns ± 3% -11.41% (p=0.000 n=10+10)
QuoteRune-6 117ns ± 5% 111ns ± 1% -4.54% (p=0.000 n=10+10)
AppendQuote-6 475ns ± 0% 396ns ± 0% -16.59% (p=0.000 n=9+10)
AppendQuoteRune-6 32.0ns ± 0% 27.4ns ± 0% -14.41% (p=0.000 n=8+9)
Change-Id: I7704f5c51b46aed2d8f033de74c75140fc35036c
Reviewed-on: https://go-review.googlesource.com/54394
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/ssa/gen/genericOps.go b/src/cmd/compile/internal/ssa/gen/genericOps.go
index d36910e..5ce11c7 100644
--- a/src/cmd/compile/internal/ssa/gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/gen/genericOps.go
@@ -321,8 +321,11 @@
{name: "Invalid"}, // unused value
// Memory operations
- {name: "Load", argLength: 2}, // Load from arg0. arg1=memory
- {name: "Store", argLength: 3, typ: "Mem", aux: "Typ"}, // Store arg1 to arg0. arg2=memory, aux=type. Returns memory.
+ {name: "Load", argLength: 2}, // Load from arg0. arg1=memory
+ {name: "Store", argLength: 3, typ: "Mem", aux: "Typ"}, // Store arg1 to arg0. arg2=memory, aux=type. Returns memory.
+ // The source and destination of Move may overlap in some cases. See e.g.
+ // memmove inlining in generic.rules. When inlineablememmovesize (in ../rewrite.go)
+ // returns true, we must do all loads before all stores, when lowering Move.
{name: "Move", argLength: 3, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=srcptr, arg2=mem, auxint=size, aux=type. Returns memory.
{name: "Zero", argLength: 2, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=mem, auxint=size, aux=type. Returns memory.
