# v4/Makefile -- host golden model build.
#
# JUSTIFICATION.md section 5: the host node runs the same mesh-defined
# instruction set as the hardware, so the C99 model is the reference the
# hardware is compared against -- not a host-specific reimplementation.
# There is consequently nothing v4-specific in the architecture here; the
# build is plain hosted C99 and the ISA is defined in DECOMPOSITION.md.
#
# The two builds that matter are the two cell widths.  v4/Makefile builds and
# runs the tests at both, because a width-dependent bug that only appears at
# 32 bits is exactly the failure mode the F18's 32-bit cells invite and
# exactly the one a 64-bit-only test run would miss.
#
# C99, warnings fatal.  A warning here is a defect in a model whose only job
# is to be trusted.

CC      ?= cc
CSTD    := -std=c99
WARN    := -Wall -Wextra -Wpedantic -Werror
OPT     ?= -O2 -g
CFLAGS  ?= $(CSTD) $(WARN) $(OPT)

# Anchor everything to this Makefile's directory so the build behaves the same
# whether it is invoked as `make -C v4 test` or `make -f v4/Makefile test`
# from the repository root.  Without this the wildcards below silently expand
# to nothing from the root and the build "succeeds" having compiled no tests.
HERE    := $(patsubst %/,%,$(dir $(abspath $(lastword $(MAKEFILE_LIST)))))

SRCS    := $(wildcard $(HERE)/src/*.c)
TESTS   := $(wildcard $(HERE)/tests/*.c)

# Cell widths to build and verify.  32 is the F18/Zynq case, 64 the aarch64
# host case; see DECOMPOSITION.md D-5.
WIDTHS  := 32 64

BINDIR  := $(HERE)/build

.PHONY: all test sanitize clean $(addprefix test-,$(WIDTHS))

all: test

# A build that finds no tests must fail loudly, not report a vacuous pass.  A
# loop over an empty list exits 0 having run nothing, which in CI is
# indistinguishable from a green run -- the worst possible failure mode for a
# test harness, and one this Makefile has already produced once.
ifeq ($(strip $(TESTS)),)
$(error No test sources under $(HERE)/tests -- refusing to report success)
endif

# One test binary per (width, test source) pair.  The cell width is a
# preprocessor parameter rather than a runtime one, so the two widths are
# separate compilations -- which is the point: there is no single code path
# that could paper over a width assumption.
#
# `make test` builds optimised; `make sanitize` builds the same sources under
# AddressSanitizer and UndefinedBehaviorSanitizer at both widths and runs them.
# The optimized run catches logic errors, this one catches the out-of-bounds
# ring index and the width-dependent shift that a logic-only test cannot see.
# -fno-sanitize-recover=all makes every UBSan report fatal: without it UBSan
# prints the report and carries on, and the run still says "passed".
#
# Both binaries depend on this Makefile, so a flag change rebuilds them.
define TEST_RULE
$(BINDIR)/$(1)-$(notdir $(2)): $(2) $$(SRCS) $$(wildcard $(HERE)/include/v4/*.h) $(HERE)/Makefile
	@mkdir -p $(BINDIR)
	$$(CC) $$(CFLAGS) -I$(HERE)/include -DV4_CELL_BITS=$(1) \
		$(2) $$(SRCS) -o $$@

$(BINDIR)/san-$(1)-$(notdir $(2)): $(2) $$(SRCS) $$(wildcard $(HERE)/include/v4/*.h) $(HERE)/Makefile
	@mkdir -p $(BINDIR)
	$$(CC) $$(CSTD) $$(WARN) -O1 -g -fno-omit-frame-pointer \
		-fsanitize=address,undefined -fno-sanitize-recover=all -I$(HERE)/include -DV4_CELL_BITS=$(1) \
		$(2) $$(SRCS) -o $$@
endef

# One run target per (width, test) and one prerequisite line per width, so
# adding a test file cannot redefine a recipe and the run cannot skip the
# build.  A shell loop over `$^` is avoided deliberately: `$^` is make syntax
# that does not survive the define/eval expansion, and a silently-empty loop
# list is exactly the vacuous-pass failure this file already made once.
define RUN_RULE
run-$(1)-$(notdir $(2)): $(BINDIR)/$(1)-$(notdir $(2))
	@echo "  [V4_CELL_BITS=$(1) $$@]"
	@$(BINDIR)/$(1)-$(notdir $(2))

test-$(1): run-$(1)-$(notdir $(2))
endef

# The same sources and the same assertions, under ASan+UBSan.
define SAN_RULE
san-$(1)-$(notdir $(2)): $(BINDIR)/san-$(1)-$(notdir $(2))
	@echo "  [ASan+UBSan V4_CELL_BITS=$(1) $$@]"
	@$(BINDIR)/san-$(1)-$(notdir $(2))
endef

$(foreach w,$(WIDTHS),$(foreach t,$(TESTS),$(eval $(call TEST_RULE,$(w),$(t)))))
$(foreach w,$(WIDTHS),$(foreach t,$(TESTS),$(eval $(call RUN_RULE,$(w),$(t)))))
$(foreach w,$(WIDTHS),$(foreach t,$(TESTS),$(eval $(call SAN_RULE,$(w),$(t)))))

sanitize: $(foreach w,$(WIDTHS),$(foreach t,$(TESTS),san-$(w)-$(notdir $(t))))
	@echo "all v4 tests passed under ASan+UBSan"

.PHONY: $(foreach w,$(WIDTHS),$(foreach t,$(TESTS),run-$(w)-$(notdir $(t)) san-$(w)-$(notdir $(t))))

test: $(addprefix test-,$(WIDTHS))
	@echo "all v4 tests passed"

clean:
	rm -rf $(BINDIR)