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test: test that we schedule OpArgIntReg early

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If OpArgIntReg is incorrectly scheduled, that causes it to be spilled
incorrectly, which causes the argument to not be considered live
at the start of the function.

This is the test for CL 462858

Add a brief mention of why CL 462858 is needed in the scheduling code.

Change-Id: Id199456f88d9ee5ca46d7b0353a3c2049709880e
Reviewed-on: https://go-review.googlesource.com/c/go/+/462899
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
This commit is contained in:
Keith Randall 2023-01-20 13:54:36 -08:00 committed by Keith Randall
parent 4ff074945a
commit ba91377454
2 changed files with 26 additions and 2 deletions
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6
src/cmd/compile/internal/ssa/schedule.go
View File

@ -130,8 +130,10 @@ func schedule(f *Func) {
// We want all the phis first.
score[v.ID] = ScorePhi
case v.Op == OpArgIntReg || v.Op == OpArgFloatReg:
// In-register args must be scheduled as early as possible to ensure that the
// context register is not stomped. They should only appear in the entry block.
// In-register args must be scheduled as early as possible to ensure that they
// are not stomped (similar to the closure pointer above).
// In particular, they need to come before regular OpArg operations because
// of how regalloc places spill code (see regalloc.go:placeSpills:mustBeFirst).
if b != f.Entry {
f.Fatalf("%s appeared outside of entry block, b=%s", v.Op, b.String())
}

22
test/live_regabi.go
View File

@ -11,6 +11,8 @@
package main
import "runtime"
func printnl()
//go:noescape
@ -718,3 +720,23 @@ func f44(f func() [2]*int) interface{} { // ERROR "live at entry to f44: f"
ret.s[0] = f()
return ret
}
func f45(a, b, c, d, e, f, g, h, i, j, k, l *byte) { // ERROR "live at entry to f45: a b c d e f g h i j k l"
f46(a, b, c, d, e, f, g, h, i, j, k, l) // ERROR "live at call to f46: a b c d e f g h i j k l"
runtime.KeepAlive(a)
runtime.KeepAlive(b)
runtime.KeepAlive(c)
runtime.KeepAlive(d)
runtime.KeepAlive(e)
runtime.KeepAlive(f)
runtime.KeepAlive(g)
runtime.KeepAlive(h)
runtime.KeepAlive(i)
runtime.KeepAlive(j)
runtime.KeepAlive(k)
runtime.KeepAlive(l)
}
//go:noinline
func f46(a, b, c, d, e, f, g, h, i, j, k, l *byte) {
}