go/test/prove_invert_loop_with_unused_iterators.go

// errorcheck -0 -d=ssa/prove/debug=1

//go:build amd64

package main

func invert(b func(), n int) {
	for i := 0; i < n; i++ { // ERROR "(Inverted loop iteration|Induction variable: limits \[0,\?\), increment 1)"
		b()
	}
}
cmd/compile: try to rewrite loops to count down Fixes #61629 This reduce the pressure on regalloc because then the loop only keep alive one value (the iterator) instead of the iterator and the upper bound since the comparison now acts against an immediate, often zero which can be skipped. This optimize things like: for i := 0; i < n; i++ { Or a range over a slice where the index is not used: for _, v := range someSlice { Or the new range over int from #61405: for range n { It is hit in 975 unique places while doing ./make.bash. Change-Id: I5facff8b267a0b60ea3c1b9a58c4d74cdb38f03f Reviewed-on: https://go-review.googlesource.com/c/go/+/512935 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Jorropo <jorropo.pgm@gmail.com> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Keith Randall <khr@golang.org> Auto-Submit: Keith Randall <khr@golang.org> 2023-07-25 16:19:10 +02:00			`// errorcheck -0 -d=ssa/prove/debug=1`

test: migrate remaining files to go:build syntax Most of the test cases in the test directory use the new go:build syntax already. Convert the rest. In general, try to place the build constraint line below the test directive comment in more places. For #41184. For #60268. Change-Id: I11c41a0642a8a26dc2eda1406da908645bbc005b Cq-Include-Trybots: luci.golang.try:gotip-linux-386-longtest,gotip-linux-amd64-longtest,gotip-windows-amd64-longtest Reviewed-on: https://go-review.googlesource.com/c/go/+/536236 Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> 2023-10-17 15:07:58 -04:00			`//go:build amd64`

cmd/compile: try to rewrite loops to count down Fixes #61629 This reduce the pressure on regalloc because then the loop only keep alive one value (the iterator) instead of the iterator and the upper bound since the comparison now acts against an immediate, often zero which can be skipped. This optimize things like: for i := 0; i < n; i++ { Or a range over a slice where the index is not used: for _, v := range someSlice { Or the new range over int from #61405: for range n { It is hit in 975 unique places while doing ./make.bash. Change-Id: I5facff8b267a0b60ea3c1b9a58c4d74cdb38f03f Reviewed-on: https://go-review.googlesource.com/c/go/+/512935 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Jorropo <jorropo.pgm@gmail.com> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Keith Randall <khr@golang.org> Auto-Submit: Keith Randall <khr@golang.org> 2023-07-25 16:19:10 +02:00			`package main`

			`func invert(b func(), n int) {`
			`for i := 0; i < n; i++ { // ERROR "(Inverted loop iteration\|Induction variable: limits \[0,\?\), increment 1)"`
			`b()`
			`}`
			`}`