Track PGO profiles in depinfo

src/test/run-make/track-pgo-dep-info/Makefile

@@ -0,0 +1,26 @@
+# needs-profiler-support
+# ignore-windows-gnu
+
+-include ../../run-make-fulldeps/tools.mk
+
+# FIXME(eddyb) provide `HOST_RUSTC` and `TARGET_RUSTC`
+# instead of hardcoding them everywhere they're needed.
+ifeq ($(IS_MUSL_HOST),1)
+ADDITIONAL_ARGS := $(RUSTFLAGS)
+endif
+
+all:
+	# Generate PGO profiles
+	$(BARE_RUSTC) $(ADDITIONAL_ARGS) -Cprofile-generate=$(TMPDIR)/profiles --out-dir $(TMPDIR) main.rs
+	$(TMPDIR)/main
+
+	# Merge profiles
+	"$(LLVM_BIN_DIR)/llvm-profdata" merge \
+		-o "$(TMPDIR)/merged.profdata" \
+		"$(TMPDIR)/profiles" || exit 1
+
+	# Use the profile
+	$(RUSTC) -Cprofile-use=$(TMPDIR)/merged.profdata --emit dep-info main.rs
+
+	# Check that profile file is in depinfo
+	$(CGREP) "merged.profdata" < $(TMPDIR)/main.d

src/test/run-make/track-pgo-dep-info/main.rs

@@ -0,0 +1 @@
+fn main() {}