test: make nosplit test invariant to ABI wrappers

Currently, the nosplit test disables ABI wrapper generation because it
generates a main.main in assembly, and so the ABI wrapper for calling
from runtime.main to main.main counts against the nosplit limit, which
cases some of the tests to fail.

Fix this by first entering ABI0 in a splittable context and then
calling from there into the test entry point, since this doesn't
introduce an ABI wrapper.

While we're here, this CL removes the test's check for the
framepointer experiment. That's now statically enabled, so it doesn't
appear in the experiment line, and enabling any other experiment
causes the test to think that the framepointer experiment *isn't*
enabled.

For #40724.

Change-Id: I6291eb9391f129779e726c5fc8c41b7b4a14eeb9
Reviewed-on: https://go-review.googlesource.com/c/go/+/302772
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/test/nosplit.go b/test/nosplit.go
index 8a3fa9bf3538e2b4da22a01769d833dce2cd4505..7c7e1bfd99e01ae94094d72f6c7d90e12e4935f5 100644 (file)
--- a/test/nosplit.go
+++ b/test/nosplit.go
@@ -21,6 +21,8 @@ import (
        "strings"
 )
 
+const debug = false
+
 var tests = `
 # These are test cases for the linker analysis that detects chains of
 # nosplit functions that would cause a stack overflow.
@@ -33,8 +35,8 @@ var tests = `
 # The body is assembly code, with some shorthands.
 # The shorthand 'call x' stands for CALL x(SB).
 # The shorthand 'callind' stands for 'CALL R0', where R0 is a register.
-# Each test case must define a function named main, and it must be first.
-# That is, a line beginning "main " indicates the start of a new test case.
+# Each test case must define a function named start, and it must be first.
+# That is, a line beginning "start " indicates the start of a new test case.
 # Within a stanza, ; can be used instead of \n to separate lines.
 #
 # After the function definition, the test case ends with an optional
@@ -46,41 +48,41 @@ var tests = `
 # that are only 32-bit aligned.
 
 # Ordinary function should work
-main 0
+start 0
 
 # Large frame marked nosplit is always wrong.
-main 10000 nosplit
+start 10000 nosplit
 REJECT
 
 # Calling a large frame is okay.
-main 0 call big
+start 0 call big
 big 10000
 
 # But not if the frame is nosplit.
-main 0 call big
+start 0 call big
 big 10000 nosplit
 REJECT
 
 # Recursion is okay.
-main 0 call main
+start 0 call start
 
 # Recursive nosplit runs out of space.
-main 0 nosplit call main
+start 0 nosplit call start
 REJECT
 
 # Chains of ordinary functions okay.
-main 0 call f1
+start 0 call f1
 f1 80 call f2
 f2 80
 
 # Chains of nosplit must fit in the stack limit, 128 bytes.
-main 0 call f1
+start 0 call f1
 f1 80 nosplit call f2
 f2 80 nosplit
 REJECT
 
 # Larger chains.
-main 0 call f1
+start 0 call f1
 f1 16 call f2
 f2 16 call f3
 f3 16 call f4
@@ -91,7 +93,7 @@ f7 16 call f8
 f8 16 call end
 end 1000
 
-main 0 call f1
+start 0 call f1
 f1 16 nosplit call f2
 f2 16 nosplit call f3
 f3 16 nosplit call f4
@@ -106,27 +108,27 @@ REJECT
 # Test cases near the 128-byte limit.
 
 # Ordinary stack split frame is always okay.
-main 112
-main 116
-main 120
-main 124
-main 128
-main 132
-main 136
+start 112
+start 116
+start 120
+start 124
+start 128
+start 132
+start 136
 
 # A nosplit leaf can use the whole 128-CallSize bytes available on entry.
 # (CallSize is 32 on ppc64, 8 on amd64 for frame pointer.)
-main 96 nosplit
-main 100 nosplit; REJECT ppc64 ppc64le
-main 104 nosplit; REJECT ppc64 ppc64le arm64
-main 108 nosplit; REJECT ppc64 ppc64le
-main 112 nosplit; REJECT ppc64 ppc64le arm64
-main 116 nosplit; REJECT ppc64 ppc64le
-main 120 nosplit; REJECT ppc64 ppc64le amd64 arm64
-main 124 nosplit; REJECT ppc64 ppc64le amd64
-main 128 nosplit; REJECT
-main 132 nosplit; REJECT
-main 136 nosplit; REJECT
+start 96 nosplit
+start 100 nosplit; REJECT ppc64 ppc64le
+start 104 nosplit; REJECT ppc64 ppc64le arm64
+start 108 nosplit; REJECT ppc64 ppc64le
+start 112 nosplit; REJECT ppc64 ppc64le arm64
+start 116 nosplit; REJECT ppc64 ppc64le
+start 120 nosplit; REJECT ppc64 ppc64le amd64 arm64
+start 124 nosplit; REJECT ppc64 ppc64le amd64
+start 128 nosplit; REJECT
+start 132 nosplit; REJECT
+start 136 nosplit; REJECT
 
 # Calling a nosplit function from a nosplit function requires
 # having room for the saved caller PC and the called frame.
@@ -134,55 +136,55 @@ main 136 nosplit; REJECT
 # Because arm64 doesn't save LR in the leaf, it gets an extra 8 bytes.
 # ppc64 doesn't save LR in the leaf, but CallSize is 32, so it gets 24 bytes.
 # Because AMD64 uses frame pointer, it has 8 fewer bytes.
-main 96 nosplit call f; f 0 nosplit
-main 100 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le
-main 104 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le arm64
-main 108 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le
-main 112 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 arm64
-main 116 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64
-main 120 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 arm64
-main 124 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 386
-main 128 nosplit call f; f 0 nosplit; REJECT
-main 132 nosplit call f; f 0 nosplit; REJECT
-main 136 nosplit call f; f 0 nosplit; REJECT
+start 96 nosplit call f; f 0 nosplit
+start 100 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le
+start 104 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le arm64
+start 108 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le
+start 112 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 arm64
+start 116 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64
+start 120 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 arm64
+start 124 nosplit call f; f 0 nosplit; REJECT ppc64 ppc64le amd64 386
+start 128 nosplit call f; f 0 nosplit; REJECT
+start 132 nosplit call f; f 0 nosplit; REJECT
+start 136 nosplit call f; f 0 nosplit; REJECT
 
 # Calling a splitting function from a nosplit function requires
 # having room for the saved caller PC of the call but also the
 # saved caller PC for the call to morestack.
 # Architectures differ in the same way as before.
-main 96 nosplit call f; f 0 call f
-main 100 nosplit call f; f 0 call f; REJECT ppc64 ppc64le
-main 104 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 arm64
-main 108 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64
-main 112 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 arm64
-main 116 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64
-main 120 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 386 arm64
-main 124 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 386
-main 128 nosplit call f; f 0 call f; REJECT
-main 132 nosplit call f; f 0 call f; REJECT
-main 136 nosplit call f; f 0 call f; REJECT
+start 96 nosplit call f; f 0 call f
+start 100 nosplit call f; f 0 call f; REJECT ppc64 ppc64le
+start 104 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 arm64
+start 108 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64
+start 112 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 arm64
+start 116 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64
+start 120 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 386 arm64
+start 124 nosplit call f; f 0 call f; REJECT ppc64 ppc64le amd64 386
+start 128 nosplit call f; f 0 call f; REJECT
+start 132 nosplit call f; f 0 call f; REJECT
+start 136 nosplit call f; f 0 call f; REJECT
 
 # Indirect calls are assumed to be splitting functions.
-main 96 nosplit callind
-main 100 nosplit callind; REJECT ppc64 ppc64le
-main 104 nosplit callind; REJECT ppc64 ppc64le amd64 arm64
-main 108 nosplit callind; REJECT ppc64 ppc64le amd64
-main 112 nosplit callind; REJECT ppc64 ppc64le amd64 arm64
-main 116 nosplit callind; REJECT ppc64 ppc64le amd64
-main 120 nosplit callind; REJECT ppc64 ppc64le amd64 386 arm64
-main 124 nosplit callind; REJECT ppc64 ppc64le amd64 386
-main 128 nosplit callind; REJECT
-main 132 nosplit callind; REJECT
-main 136 nosplit callind; REJECT
+start 96 nosplit callind
+start 100 nosplit callind; REJECT ppc64 ppc64le
+start 104 nosplit callind; REJECT ppc64 ppc64le amd64 arm64
+start 108 nosplit callind; REJECT ppc64 ppc64le amd64
+start 112 nosplit callind; REJECT ppc64 ppc64le amd64 arm64
+start 116 nosplit callind; REJECT ppc64 ppc64le amd64
+start 120 nosplit callind; REJECT ppc64 ppc64le amd64 386 arm64
+start 124 nosplit callind; REJECT ppc64 ppc64le amd64 386
+start 128 nosplit callind; REJECT
+start 132 nosplit callind; REJECT
+start 136 nosplit callind; REJECT
 
 # Issue 7623
-main 0 call f; f 112
-main 0 call f; f 116
-main 0 call f; f 120
-main 0 call f; f 124
-main 0 call f; f 128
-main 0 call f; f 132
-main 0 call f; f 136
+start 0 call f; f 112
+start 0 call f; f 116
+start 0 call f; f 120
+start 0 call f; f 124
+start 0 call f; f 128
+start 0 call f; f 132
+start 0 call f; f 136
 `
 
 var (
@@ -199,17 +201,6 @@ func main() {
                goarch = runtime.GOARCH
        }
 
-       version, err := exec.Command("go", "tool", "compile", "-V").Output()
-       if err != nil {
-               bug()
-               fmt.Printf("running go tool compile -V: %v\n", err)
-               return
-       }
-       if s := string(version); goarch == "amd64" && strings.Contains(s, "X:") && !strings.Contains(s, "framepointer") {
-               // Skip this test if framepointer is NOT enabled on AMD64
-               return
-       }
-
        dir, err := ioutil.TempDir("", "go-test-nosplit")
        if err != nil {
                bug()
@@ -231,7 +222,7 @@ func main() {
 TestCases:
        for len(tests) > 0 {
                var stanza string
-               i := strings.Index(tests, "\nmain ")
+               i := strings.Index(tests, "\nstart ")
                if i < 0 {
                        stanza, tests = tests, ""
                } else {
@@ -293,6 +284,14 @@ TestCases:
                        fmt.Fprintf(&buf, "#define REGISTER AX\n")
                }
 
+               // Since all of the functions we're generating are
+               // ABI0, first enter ABI0 via a splittable function
+               // and then go to the chain we're testing. This way we
+               // don't have to account for ABI wrappers in the chain.
+               fmt.Fprintf(&gobuf, "func main0()\n")
+               fmt.Fprintf(&gobuf, "func main() { main0() }\n")
+               fmt.Fprintf(&buf, "TEXT ·main0(SB),0,$0-0\n\tCALL ·start(SB)\n")
+
                for _, line := range strings.Split(lines, "\n") {
                        line = strings.TrimSpace(line)
                        if line == "" {
@@ -346,6 +345,12 @@ TestCases:
                        }
                }
 
+               if debug {
+                       fmt.Printf("===\n%s\n", strings.TrimSpace(stanza))
+                       fmt.Printf("-- main.go --\n%s", gobuf.String())
+                       fmt.Printf("-- asm.s --\n%s", buf.String())
+               }
+
                if err := ioutil.WriteFile(filepath.Join(dir, "asm.s"), buf.Bytes(), 0666); err != nil {
                        log.Fatal(err)
                }
@@ -353,14 +358,7 @@ TestCases:
                        log.Fatal(err)
                }
 
-               // Turn off ABI0 wrapper generation for now. The problem here is
-               // that in these test cases main.main is an assembly routine,
-               // thus calls to it will have to go through an ABI wrapper. The
-               // ABI wrapper will consume some stack space, which throws off
-               // the numbers.
-               workaround := "-gcflags=-abiwrap=0"
-
-               cmd := exec.Command("go", "build", workaround)
+               cmd := exec.Command("go", "build")
                cmd.Dir = dir
                output, err := cmd.CombinedOutput()
                if err == nil {