cmd/compile: redo nil checks
Get rid of BlockCheck. Josh goaded me into it, and I went
down a rabbithole making it happen.
NilCheck now panics if the pointer is nil and returns void, as before.
BlockCheck is gone, and NilCheck is no longer a Control value for
any block. It just exists (and deadcode knows not to throw it away).
I rewrote the nilcheckelim pass to handle this case. In particular,
there can now be multiple NilCheck ops per block.
I moved all of the arch-dependent nil check elimination done as
part of ssaGenValue into its own proper pass, so we don't have to
duplicate that code for every architecture.
Making the arch-dependent nil check its own pass means I needed
to add a bunch of flags to the opcode table so I could write
the code without arch-dependent ops everywhere.
Change-Id: I419f891ac9b0de313033ff09115c374163416a9f
Reviewed-on: https://go-review.googlesource.com/29120
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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 def6a83..c1bc38c 100644
--- a/src/cmd/compile/internal/ssa/gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/gen/genericOps.go
@@ -303,6 +303,7 @@
{name: "SP"}, // stack pointer
{name: "SB", typ: "Uintptr"}, // static base pointer (a.k.a. globals pointer)
{name: "Func", aux: "Sym"}, // entry address of a function
+ {name: "Invalid"}, // unused value
// Memory operations
{name: "Load", argLength: 2}, // Load from arg0. arg1=memory
@@ -354,7 +355,7 @@
{name: "IsNonNil", argLength: 1, typ: "Bool"}, // arg0 != nil
{name: "IsInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 < arg1. arg1 is guaranteed >= 0.
{name: "IsSliceInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 <= arg1. arg1 is guaranteed >= 0.
- {name: "NilCheck", argLength: 2, typ: "Void"}, // arg0=ptr, arg1=mem. Panics if arg0 is nil, returns void.
+ {name: "NilCheck", argLength: 2, typ: "Void"}, // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns void.
// Pseudo-ops
{name: "GetG", argLength: 1}, // runtime.getg() (read g pointer). arg0=mem
@@ -476,7 +477,6 @@
{name: "Plain"}, // a single successor
{name: "If"}, // 2 successors, if control goto Succs[0] else goto Succs[1]
{name: "Defer"}, // 2 successors, Succs[0]=defer queued, Succs[1]=defer recovered. control is call op (of memory type)
- {name: "Check"}, // 1 successor, control is nilcheck op (of void type)
{name: "Ret"}, // no successors, control value is memory result
{name: "RetJmp"}, // no successors, jumps to b.Aux.(*gc.Sym)
{name: "Exit"}, // no successors, control value generates a panic
