cmd/compile: use CDF to determine PGO inline threshold

Currently in PGO we use a percentage threshold to determine if a
callsite is hot. This CL uses a different method -- treating the
hottest callsites that make up cumulatively top X% of total edge
weights as hot (X=95 for now). This default might work better for
a wider range of profiles. (The absolute threshold can still be
changed by a flag.)

For #55022.

Change-Id: I7e3b6f0c3cf23f9a89dd5994c10075b498bf14ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/447016
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>

1 files changed, 33 insertions, 33 deletions

diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index 18422256ab..6cb7a54cad 100644
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -16,39 +16,39 @@ var Debug DebugFlags
 // The -d option takes a comma-separated list of settings.
 // Each setting is name=value; for ints, name is short for name=1.
 type DebugFlags struct {
-	Append                     int    `help:"print information about append compilation"`
-	Checkptr                   int    `help:"instrument unsafe pointer conversions\n0: instrumentation disabled\n1: conversions involving unsafe.Pointer are instrumented\n2: conversions to unsafe.Pointer force heap allocation"`
-	Closure                    int    `help:"print information about closure compilation"`
-	DclStack                   int    `help:"run internal dclstack check"`
-	Defer                      int    `help:"print information about defer compilation"`
-	DisableNil                 int    `help:"disable nil checks"`
-	DumpPtrs                   int    `help:"show Node pointers values in dump output"`
-	DwarfInl                   int    `help:"print information about DWARF inlined function creation"`
-	Export                     int    `help:"print export data"`
-	GCProg                     int    `help:"print dump of GC programs"`
-	Gossahash                  string `help:"hash value for use in debugging the compiler"`
-	InlFuncsWithClosures       int    `help:"allow functions with closures to be inlined"`
-	Libfuzzer                  int    `help:"enable coverage instrumentation for libfuzzer"`
-	LocationLists              int    `help:"print information about DWARF location list creation"`
-	Nil                        int    `help:"print information about nil checks"`
-	NoOpenDefer                int    `help:"disable open-coded defers"`
-	NoRefName                  int    `help:"do not include referenced symbol names in object file"`
-	PCTab                      string `help:"print named pc-value table\nOne of: pctospadj, pctofile, pctoline, pctoinline, pctopcdata"`
-	Panic                      int    `help:"show all compiler panics"`
-	Reshape                    int    `help:"print information about expression reshaping"`
-	Shapify                    int    `help:"print information about shaping recursive types"`
-	Slice                      int    `help:"print information about slice compilation"`
-	SoftFloat                  int    `help:"force compiler to emit soft-float code"`
-	SyncFrames                 int    `help:"how many writer stack frames to include at sync points in unified export data"`
-	TypeAssert                 int    `help:"print information about type assertion inlining"`
-	TypecheckInl               int    `help:"eager typechecking of inline function bodies"`
-	Unified                    int    `help:"enable unified IR construction"`
-	WB                         int    `help:"print information about write barriers"`
-	ABIWrap                    int    `help:"print information about ABI wrapper generation"`
-	MayMoreStack               string `help:"call named function before all stack growth checks"`
-	InlineHotCallSiteThreshold string `help:"threshold percentage for determining call sites as hot candidates for inlining"`
-	InlineHotBudget            int    `help:"inline budget for hot functions"`
-	PGOInline                  int    `help:"debug profile-guided inlining"`
+	Append                        int    `help:"print information about append compilation"`
+	Checkptr                      int    `help:"instrument unsafe pointer conversions\n0: instrumentation disabled\n1: conversions involving unsafe.Pointer are instrumented\n2: conversions to unsafe.Pointer force heap allocation"`
+	Closure                       int    `help:"print information about closure compilation"`
+	DclStack                      int    `help:"run internal dclstack check"`
+	Defer                         int    `help:"print information about defer compilation"`
+	DisableNil                    int    `help:"disable nil checks"`
+	DumpPtrs                      int    `help:"show Node pointers values in dump output"`
+	DwarfInl                      int    `help:"print information about DWARF inlined function creation"`
+	Export                        int    `help:"print export data"`
+	GCProg                        int    `help:"print dump of GC programs"`
+	Gossahash                     string `help:"hash value for use in debugging the compiler"`
+	InlFuncsWithClosures          int    `help:"allow functions with closures to be inlined"`
+	Libfuzzer                     int    `help:"enable coverage instrumentation for libfuzzer"`
+	LocationLists                 int    `help:"print information about DWARF location list creation"`
+	Nil                           int    `help:"print information about nil checks"`
+	NoOpenDefer                   int    `help:"disable open-coded defers"`
+	NoRefName                     int    `help:"do not include referenced symbol names in object file"`
+	PCTab                         string `help:"print named pc-value table\nOne of: pctospadj, pctofile, pctoline, pctoinline, pctopcdata"`
+	Panic                         int    `help:"show all compiler panics"`
+	Reshape                       int    `help:"print information about expression reshaping"`
+	Shapify                       int    `help:"print information about shaping recursive types"`
+	Slice                         int    `help:"print information about slice compilation"`
+	SoftFloat                     int    `help:"force compiler to emit soft-float code"`
+	SyncFrames                    int    `help:"how many writer stack frames to include at sync points in unified export data"`
+	TypeAssert                    int    `help:"print information about type assertion inlining"`
+	TypecheckInl                  int    `help:"eager typechecking of inline function bodies"`
+	Unified                       int    `help:"enable unified IR construction"`
+	WB                            int    `help:"print information about write barriers"`
+	ABIWrap                       int    `help:"print information about ABI wrapper generation"`
+	MayMoreStack                  string `help:"call named function before all stack growth checks"`
+	InlineHotCallSiteCDFThreshold string `help:"cummulative threshold percentage for determining call sites as hot candidates for inlining"`
+	InlineHotBudget               int    `help:"inline budget for hot functions"`
+	PGOInline                     int    `help:"debug profile-guided inlining"`
 
 	ConcurrentOk bool // true if only concurrentOk flags seen
 }