From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Tue, 21 Sep 2021 21:22:51 +0000 (-0700)
Subject: runtime: move entry method from _func to funcInfo
X-Git-Tag: go1.18beta1~1164
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=f0c79caa1398b6a840ec9406eb34b46a125ecb82;p=gostls13.git

runtime: move entry method from _func to funcInfo

This will be required when we change from storing entry PCs in _func
to entry PC offsets, which are relative to the containing module.

Notably, almost all uses of the entry method were already called
on a funcInfo. Only Func.Entry incurs the additional module
lookup cost.

This makes Entry considerably slower, but it is probably
still fast enough in absolute terms that it is OK.

name             old time/op  new time/op  delta
Func/Name-8      8.86ns ± 0%  8.33ns ± 2%    -5.92%  (p=0.000 n=12+13)
Func/Entry-8     0.64ns ± 0%  2.62ns ±36%  +310.07%  (p=0.000 n=14+15)
Func/FileLine-8  24.5ns ± 0%  25.0ns ± 4%    +2.21%  (p=0.015 n=14+13)

Change-Id: Ia2d5de5f2f83fab334f1875452b9e8e87651d340
Reviewed-on: https://go-review.googlesource.com/c/go/+/351461
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/cmd/compile/internal/test/inl_test.go b/src/cmd/compile/internal/test/inl_test.go
index 06afe835e2..89247fbabf 100644
--- a/src/cmd/compile/internal/test/inl_test.go
+++ b/src/cmd/compile/internal/test/inl_test.go
@@ -65,7 +65,7 @@ func TestIntendedInlining(t *testing.T) {
 			"(*bmap).keys",
 			"(*bmap).overflow",
 			"(*waitq).enqueue",
-			"(*_func).entry",
+			"funcInfo.entry",
 
 			// GC-related ones
 			"cgoInRange",
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index a11e22130d..7a9bb3e06b 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -272,11 +272,14 @@ func (f *Func) raw() *_func {
 }
 
 func (f *Func) funcInfo() funcInfo {
-	fn := f.raw()
+	return f.raw().funcInfo()
+}
+
+func (f *_func) funcInfo() funcInfo {
 	// Find the module containing fn. fn is located in the pclntable.
 	// The unsafe.Pointer to uintptr conversions and arithmetic
 	// are safe because we are working with module addresses.
-	ptr := uintptr(unsafe.Pointer(fn))
+	ptr := uintptr(unsafe.Pointer(f))
 	var mod *moduledata
 	for datap := &firstmoduledata; datap != nil; datap = datap.next {
 		if len(datap.pclntable) == 0 {
@@ -288,7 +291,7 @@ func (f *Func) funcInfo() funcInfo {
 			break
 		}
 	}
-	return funcInfo{fn, mod}
+	return funcInfo{f, mod}
 }
 
 // PCDATA and FUNCDATA table indexes.
@@ -682,7 +685,7 @@ func (f *Func) Entry() uintptr {
 		fi := (*funcinl)(unsafe.Pointer(fn))
 		return fi.entry
 	}
-	return fn.entry()
+	return fn.funcInfo().entry()
 }
 
 // FileLine returns the file name and line number of the
@@ -735,7 +738,7 @@ func (f *_func) isInlined() bool {
 }
 
 // entry returns the entry PC for f.
-func (f *_func) entry() uintptr {
+func (f funcInfo) entry() uintptr {
 	return f.entryPC
 }