From 2ad0bf82fc9ca382136232a26e5775777c8bfff9 Mon Sep 17 00:00:00 2001
From: John McMaster <johndmcmaster@gmail.com>
Date: Wed, 12 Sep 2018 14:03:33 -0700
Subject: [PATCH] timfuz: ALLOW_ZERO_EQN

Signed-off-by: John McMaster <johndmcmaster@gmail.com>
---
 fuzzers/007-timing/projects/corner.mk          | 6 +++++-
 fuzzers/007-timing/projects/oneblinkw/Makefile | 2 ++
 fuzzers/007-timing/projects/project.mk         | 1 +
 fuzzers/007-timing/timfuz_solve.py             | 2 ++
 4 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fuzzers/007-timing/projects/corner.mk b/fuzzers/007-timing/projects/corner.mk
index c4ac2d23..5ae80ca8 100644
--- a/fuzzers/007-timing/projects/corner.mk
+++ b/fuzzers/007-timing/projects/corner.mk
@@ -2,6 +2,7 @@
 
 TIMFUZ_DIR=$(XRAY_DIR)/fuzzers/007-timing
 CORNER=slow_max
+ALLOW_ZERO_EQN?=N
 
 all: build/$(CORNER)/tilea.json
 
@@ -20,6 +21,9 @@ clean:
 build/$(CORNER):
 	mkdir build/$(CORNER)
 
+build/checksub:
+	false
+
 build/$(CORNER)/leastsq.csv: build/sub.json build/grouped.csv build/checksub build/$(CORNER)
 	# Create a rough timing model that approximately fits the given paths
 	python3 $(TIMFUZ_DIR)/solve_leastsq.py --sub-json build/sub.json build/grouped.csv --corner $(CORNER) --out build/$(CORNER)/leastsq.csv.tmp
@@ -27,7 +31,7 @@ build/$(CORNER)/leastsq.csv: build/sub.json build/grouped.csv build/checksub bui
 
 build/$(CORNER)/linprog.csv: build/$(CORNER)/leastsq.csv build/grouped.csv
 	# Tweak rough timing model, making sure all constraints are satisfied
-	python3 $(TIMFUZ_DIR)/solve_linprog.py --sub-json build/sub.json --sub-csv build/$(CORNER)/leastsq.csv --massage build/grouped.csv --corner $(CORNER) --out build/$(CORNER)/linprog.csv.tmp
+	ALLOW_ZERO_EQN=$(ALLOW_ZERO_EQN) python3 $(TIMFUZ_DIR)/solve_linprog.py --sub-json build/sub.json --sub-csv build/$(CORNER)/leastsq.csv --massage build/grouped.csv --corner $(CORNER) --out build/$(CORNER)/linprog.csv.tmp
 	mv build/$(CORNER)/linprog.csv.tmp build/$(CORNER)/linprog.csv
 
 build/$(CORNER)/flat.csv: build/$(CORNER)/linprog.csv
diff --git a/fuzzers/007-timing/projects/oneblinkw/Makefile b/fuzzers/007-timing/projects/oneblinkw/Makefile
index 9c8b1947..5e5721b7 100644
--- a/fuzzers/007-timing/projects/oneblinkw/Makefile
+++ b/fuzzers/007-timing/projects/oneblinkw/Makefile
@@ -1,2 +1,4 @@
+# so simple that likely no linprog adjustments will be needed
+ALLOW_ZERO_EQN?=Y
 include ../project.mk
 
diff --git a/fuzzers/007-timing/projects/project.mk b/fuzzers/007-timing/projects/project.mk
index c0b3d1a3..daa79aeb 100644
--- a/fuzzers/007-timing/projects/project.mk
+++ b/fuzzers/007-timing/projects/project.mk
@@ -7,6 +7,7 @@ SPECIMENS_OK := $(addsuffix /OK,$(SPECIMENS))
 CSVS := $(addsuffix /timing3.csv,$(SPECIMENS))
 TIMFUZ_DIR=$(XRAY_DIR)/fuzzers/007-timing
 RREF_CORNER=slow_max
+ALLOW_ZERO_EQN?=N
 
 TILEA_JSONS=build/fast_max/tilea.json build/fast_min/tilea.json build/slow_max/tilea.json build/slow_min/tilea.json
 
diff --git a/fuzzers/007-timing/timfuz_solve.py b/fuzzers/007-timing/timfuz_solve.py
index 47373411..ccd2b738 100644
--- a/fuzzers/007-timing/timfuz_solve.py
+++ b/fuzzers/007-timing/timfuz_solve.py
@@ -142,6 +142,8 @@ def run(fns_in, corner, run_corner, sub_json=None, sub_csv=None, dedup=True, mas
         try:
             Ads, b = massage_equations(Ads, b, corner=corner)
         except SimplifiedToZero:
+            if os.getenv('ALLOW_ZERO_EQN', 'N') != 'Y':
+                raise
             print('WARNING: simplified to zero equations')
             Ads = []
             b = []