[build] Avoid spurious "make clean" when building for the first time

The function trace recorder build logic defaults to making "clean" a
dependency of the first build in a clean checkout.  This is redundant
and causes problems if the build process spins up multiple make
invocations to handle multiple build architectures.

Fix by replacing with logic based on the known-working patterns used
for the ASSERT and PROFILE build parameters.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index 91be542abd38b928c04864ded78c8bcb14b5182a..f379ff4ef04a5550e0d45d6506a668fe9540f605 100644 (file)
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -468,35 +468,6 @@ ASFLAGS            += --fatal-warnings
 HOST_CFLAGS    += -Werror
 endif
 
-# Function trace recorder state in the last build.  This is needed
-# in order to correctly rebuild whenever the function recorder is
-# enabled/disabled.
-#
-FNREC_STATE    := $(BIN)/.fnrec.state
-ifeq ($(wildcard $(FNREC_STATE)),)
-FNREC_OLD      := <invalid>
-else
-FNREC_OLD      := $(shell cat $(FNREC_STATE))
-endif
-ifeq ($(FNREC_OLD),$(FNREC))
-$(FNREC_STATE) :
-else
-$(FNREC_STATE) : clean
-$(shell $(ECHO) "$(FNREC)" > $(FNREC_STATE))
-endif
-
-VERYCLEANUP    += $(FNREC_STATE)
-MAKEDEPS       += $(FNREC_STATE)
-
-ifeq ($(FNREC),1)
-# Enabling -finstrument-functions affects gcc's analysis and leads to spurious
-# warnings about use of uninitialised variables.
-#
-CFLAGS         += -Wno-uninitialized
-CFLAGS         += -finstrument-functions
-CFLAGS         += -finstrument-functions-exclude-file-list=core/fnrec.c
-endif
-
 # Enable per-item sections and section garbage collection.  Note that
 # some older versions of gcc support -fdata-sections but treat it as
 # implying -fno-common, which would break our build.  Some other older
@@ -808,6 +779,38 @@ include/ipxe/profile.h : $(PROFILE_LIST)
 
 .PRECIOUS : include/ipxe/profile.h
 
+# (Single-element) list of function recorder configuration
+#
+FNREC_LIST := $(BIN)/.fnrec.list
+ifeq ($(wildcard $(FNREC_LIST)),)
+FNREC_OLD := <invalid>
+else
+FNREC_OLD := $(shell cat $(FNREC_LIST))
+endif
+ifneq ($(FNREC_OLD),$(FNREC))
+$(shell $(ECHO) "$(FNREC)" > $(FNREC_LIST))
+endif
+
+$(FNREC_LIST) : $(MAKEDEPS)
+
+VERYCLEANUP += $(FNREC_LIST)
+
+# Function recorder configuration
+#
+ifeq ($(FNREC),1)
+# Enabling -finstrument-functions affects gcc's analysis and leads to spurious
+# warnings about use of uninitialised variables.
+#
+CFLAGS         += -Wno-uninitialized
+CFLAGS         += -finstrument-functions
+CFLAGS         += -finstrument-functions-exclude-file-list=core/fnrec.c
+endif
+
+include/compiler.h : $(FNREC_LIST)
+       $(Q)$(TOUCH) $@
+
+.PRECIOUS : include/compiler.h
+
 # These files use .incbin inline assembly to include a binary file.
 # Unfortunately ccache does not detect this dependency and caches
 # builds even when the binary file has changed.