From 8773fd5897d1057dc8f87d4ffd13c96a708080e8 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Sun, 28 Dec 2014 21:27:51 +0100
Subject: [PATCH] Added memhasher (yosys -M)

---
 kernel/driver.cc | 11 +++++++++--
 kernel/rtlil.cc  |  3 +++
 kernel/yosys.cc  | 37 +++++++++++++++++++++++++++++++++++++
 kernel/yosys.h   |  7 +++++++
 4 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/kernel/driver.cc b/kernel/driver.cc
index 4700bf61b..9a81d8a48 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -151,8 +151,11 @@ int main(int argc, char **argv)
 		printf("    -m module_file\n");
 		printf("        load the specified module (aka plugin)\n");
 		printf("\n");
+		printf("    -M\n");
+		printf("        will slightly randomize allocated pointer addresses. for debugging\n");
+		printf("\n");
 		printf("    -A\n");
-		printf("        will call abort() at the end of the script. useful for debugging\n");
+		printf("        will call abort() at the end of the script. for debugging\n");
 		printf("\n");
 		printf("    -V\n");
 		printf("        print version information and exit\n");
@@ -174,10 +177,13 @@ int main(int argc, char **argv)
 	}
 
 	int opt;
-	while ((opt = getopt(argc, argv, "AQTVSm:f:Hh:b:o:p:l:qv:tds:c:")) != -1)
+	while ((opt = getopt(argc, argv, "MAQTVSm:f:Hh:b:o:p:l:qv:tds:c:")) != -1)
 	{
 		switch (opt)
 		{
+		case 'M':
+			memhasher_on();
+			break;
 		case 'A':
 			call_abort = true;
 			break;
@@ -407,6 +413,7 @@ int main(int argc, char **argv)
 	}
 #endif
 
+	memhasher_off();
 	if (call_abort)
 		abort();
 
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 6f2d367d6..cdbaa5bbf 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -1766,6 +1766,9 @@ RTLIL::Cell::Cell() : module(nullptr)
 {
 	static unsigned int hashidx_count = 0;
 	hashidx_ = hashidx_count++;
+
+	// log("#memtrace# %p\n", this);
+	memhasher();
 }
 
 bool RTLIL::Cell::hasPort(RTLIL::IdString portname) const
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 6cc643152..52bd066b7 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -55,6 +55,43 @@ RTLIL::Design *yosys_design = NULL;
 Tcl_Interp *yosys_tcl_interp = NULL;
 #endif
 
+bool memhasher_active = false;
+uint32_t memhasher_rng;
+std::vector<void*> memhasher_store;
+
+void memhasher_on()
+{
+	memhasher_rng += time(NULL) << 16 ^ getpid();
+	memhasher_store.resize(0x10000);
+	memhasher_active = true;
+}
+
+void memhasher_off()
+{
+	for (auto p : memhasher_store)
+		if (p) free(p);
+	memhasher_store.clear();
+	memhasher_active = false;
+}
+
+void memhasher_do()
+{
+	memhasher_rng ^= memhasher_rng << 13;
+	memhasher_rng ^= memhasher_rng >> 17;
+	memhasher_rng ^= memhasher_rng << 5;
+
+	int size, index = (memhasher_rng >> 4) & 0xffff;
+	switch (memhasher_rng & 7) {
+		case 0: size =   16; break;
+		case 1: size =  256; break;
+		case 2: size = 1024; break;
+		case 3: size = 4096; break;
+		default: size = 0;
+	}
+	if (index < 16) size *= 16;
+	memhasher_store[index] = realloc(memhasher_store[index], size);
+}
+
 std::string stringf(const char *fmt, ...)
 {
 	std::string string;
diff --git a/kernel/yosys.h b/kernel/yosys.h
index b653941ce..50a159939 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -169,6 +169,13 @@ template<> struct hash_ops<const RTLIL::Module*> : hash_obj_ops {};
 template<> struct hash_ops<const RTLIL::Design*> : hash_obj_ops {};
 template<> struct hash_ops<const RTLIL::Monitor*> : hash_obj_ops {};
 
+void memhasher_on();
+void memhasher_off();
+void memhasher_do();
+
+extern bool memhasher_active;
+inline void memhasher() { if (memhasher_active) memhasher_do(); }
+
 std::string stringf(const char *fmt, ...) YS_ATTRIBUTE(format(printf, 1, 2));
 std::string vstringf(const char *fmt, va_list ap);
 int readsome(std::istream &f, char *s, int n);
-- 
2.30.2