From 7889fea1dc4aedc8d1a8f9ce30d8c0d19b05436a Mon Sep 17 00:00:00 2001
From: Tyler Yahn <MrAlias@users.noreply.github.com>
Date: Thu, 31 Oct 2024 08:54:13 -0700
Subject: [PATCH] Update Makefile to only generate what is needed  (#1213)

* Update Makefile to only generate what is needed

Use depinfo files and make targets ensure that generate is only run when
needed.

* Update generate cmd to use env vars

* Ignore the depfiles

* Add generate/all target

* Pattern match generate targets

* Remove go-mod-tidy as dep of generate
---
 .gitignore                                    |  1 +
 Makefile                                      | 35 +++++++++++++------
 .../instrumentation/bpf/database/sql/probe.go |  2 +-
 .../segmentio/kafka-go/consumer/probe.go      |  2 +-
 .../segmentio/kafka-go/producer/probe.go      |  2 +-
 .../bpf/go.opentelemetry.io/auto/sdk/probe.go |  2 +-
 .../otel/traceglobal/probe.go                 |  2 +-
 .../google.golang.org/grpc/client/probe.go    |  2 +-
 .../google.golang.org/grpc/server/probe.go    |  2 +-
 .../bpf/net/http/client/probe.go              |  4 +--
 .../bpf/net/http/server/probe.go              |  2 +-
 11 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/.gitignore b/.gitignore
index 64aecb99c..e7c8b6498 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 *.so
 *.dylib
 **/*.o
+**/*.go.d
 .tools/
 **/internal/test/e2e/*/main
 
diff --git a/Makefile b/Makefile
index 5031f8913..ac18e4137 100644
--- a/Makefile
+++ b/Makefile
@@ -2,15 +2,19 @@
 # Assume the Makefile is in the root of the repository.
 REPODIR := $(shell dirname $(realpath $(firstword $(MAKEFILE_LIST))))
 
+# Used by bpf2go to generate make compatible depinfo files.
+export BPF2GO_MAKEBASE := $(REPODIR)
+
 TOOLS_MOD_DIR := ./internal/tools
 TOOLS = $(CURDIR)/.tools
 
 ALL_GO_MOD_DIRS := $(shell find . -type f -name 'go.mod' ! -path './LICENSES/*' -exec dirname {} \; | sort)
 ALL_GO_MODS := $(shell find . -type f -name 'go.mod' ! -path '$(TOOLS_MOD_DIR)/*' ! -path './LICENSES/*' | sort)
 
-# Build the list of include directories to compile the bpf program
-BPF_INCLUDE += -I${REPODIR}/internal/include/libbpf
-BPF_INCLUDE += -I${REPODIR}/internal/include
+# BPF compile time dependencies.
+BPF2GO_CFLAGS += -I${REPODIR}/internal/include/libbpf
+BPF2GO_CFLAGS += -I${REPODIR}/internal/include
+export BPF2GO_CFLAGS
 
 # Go default variables
 GOCMD?= go
@@ -54,14 +58,25 @@ TEST_TARGETS := test-verbose test-ebpf
 test-ebpf: ARGS = -tags=ebpf_test -run ^TestEBPF # These need to be run with sudo.
 test-verbose: ARGS = -v
 $(TEST_TARGETS): test
-test: generate $(ALL_GO_MODS:%=test/%)
+test: go-mod-tidy generate $(ALL_GO_MODS:%=test/%)
 test/%/go.mod:
 	@cd $* && $(GOCMD) test $(ARGS) ./...
 
-.PHONY: generate
-generate: export CFLAGS := $(BPF_INCLUDE)
-generate: go-mod-tidy
-generate:
+PROBE_ROOT = internal/pkg/instrumentation/bpf/
+PROBE_GEN_GO := $(shell find $(PROBE_ROOT) -type f -name 'bpf_*_bpfe[lb].go')
+PROBE_GEN_OBJ := $(PROBE_GEN_GO:.go=.o)
+
+# Include all depinfo files to ensure we only re-generate when needed.
+-include $(shell find $(PROBE_ROOT) -type f -name 'bpf_*_bpfel.go.d')
+
+.PHONY: generate generate/all
+generate: $(PROBE_GEN_GO)
+$(PROBE_GEN_GO): %.go: %.o
+
+$(PROBE_GEN_OBJ):
+	$(GOCMD) generate ./$(dir $@)...
+
+generate/all:
 	$(GOCMD) generate ./...
 
 .PHONY: docker-generate
@@ -85,7 +100,7 @@ go-mod-tidy/%:
 .PHONY: golangci-lint golangci-lint-fix
 golangci-lint-fix: ARGS=--fix
 golangci-lint-fix: golangci-lint
-golangci-lint: generate $(ALL_GO_MOD_DIRS:%=golangci-lint/%)
+golangci-lint: go-mod-tidy generate $(ALL_GO_MOD_DIRS:%=golangci-lint/%)
 golangci-lint/%: DIR=$*
 golangci-lint/%: | $(GOLANGCI_LINT)
 	@echo 'golangci-lint $(if $(ARGS),$(ARGS) ,)$(DIR)' \
@@ -93,7 +108,7 @@ golangci-lint/%: | $(GOLANGCI_LINT)
 		&& $(GOLANGCI_LINT) run --allow-serial-runners --timeout=2m0s $(ARGS)
 
 .PHONY: build
-build: generate
+build: go-mod-tidy generate
 	CGO_ENABLED=$(CGO_ENABLED) $(GOCMD) build -o otel-go-instrumentation ./cli/...
 
 .PHONY: docker-build
diff --git a/internal/pkg/instrumentation/bpf/database/sql/probe.go b/internal/pkg/instrumentation/bpf/database/sql/probe.go
index c70a2796b..7392d5cbd 100644
--- a/internal/pkg/instrumentation/bpf/database/sql/probe.go
+++ b/internal/pkg/instrumentation/bpf/database/sql/probe.go
@@ -18,7 +18,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/instrumentation/utils"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/consumer/probe.go b/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/consumer/probe.go
index fe2998fa7..5b3c89256 100644
--- a/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/consumer/probe.go
+++ b/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/consumer/probe.go
@@ -19,7 +19,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/producer/probe.go b/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/producer/probe.go
index 528071bcf..d08b09bdd 100644
--- a/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/producer/probe.go
+++ b/internal/pkg/instrumentation/bpf/github.com/segmentio/kafka-go/producer/probe.go
@@ -18,7 +18,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/auto/sdk/probe.go b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/auto/sdk/probe.go
index 1347ea1e8..8d25a372f 100644
--- a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/auto/sdk/probe.go
+++ b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/auto/sdk/probe.go
@@ -21,7 +21,7 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 // New returns a new [probe.Probe].
 func New(logger *slog.Logger) probe.Probe {
diff --git a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go
index 56a90c411..399f16c7a 100644
--- a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go
+++ b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go
@@ -25,7 +25,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/instrumentation/context"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/google.golang.org/grpc/client/probe.go b/internal/pkg/instrumentation/bpf/google.golang.org/grpc/client/probe.go
index 90adee925..e0493509f 100644
--- a/internal/pkg/instrumentation/bpf/google.golang.org/grpc/client/probe.go
+++ b/internal/pkg/instrumentation/bpf/google.golang.org/grpc/client/probe.go
@@ -22,7 +22,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/google.golang.org/grpc/server/probe.go b/internal/pkg/instrumentation/bpf/google.golang.org/grpc/server/probe.go
index 0fec3fae5..7630ae9dd 100644
--- a/internal/pkg/instrumentation/bpf/google.golang.org/grpc/server/probe.go
+++ b/internal/pkg/instrumentation/bpf/google.golang.org/grpc/server/probe.go
@@ -24,7 +24,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/net/http/client/probe.go b/internal/pkg/instrumentation/bpf/net/http/client/probe.go
index 7fd04c55d..81df309b3 100644
--- a/internal/pkg/instrumentation/bpf/net/http/client/probe.go
+++ b/internal/pkg/instrumentation/bpf/net/http/client/probe.go
@@ -24,8 +24,8 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf_no_tp ./bpf/probe.bpf.c -- -DNO_HEADER_PROPAGATION
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf_no_tp ./bpf/probe.bpf.c -- -DNO_HEADER_PROPAGATION
 
 const (
 	// pkg is the package being instrumented.
diff --git a/internal/pkg/instrumentation/bpf/net/http/server/probe.go b/internal/pkg/instrumentation/bpf/net/http/server/probe.go
index 2b305148d..59d46f8d7 100644
--- a/internal/pkg/instrumentation/bpf/net/http/server/probe.go
+++ b/internal/pkg/instrumentation/bpf/net/http/server/probe.go
@@ -23,7 +23,7 @@ import (
 	"go.opentelemetry.io/auto/internal/pkg/structfield"
 )
 
-//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 -cc clang -cflags $CFLAGS bpf ./bpf/probe.bpf.c
+//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -target amd64,arm64 bpf ./bpf/probe.bpf.c
 
 const (
 	// pkg is the package being instrumented.