proc_clean: fix order of switch insertion.

Fixes #1268.

Makefile

@@ -695,6 +695,7 @@ test: $(TARGETS) $(EXTRA_TARGETS)
 	+cd tests/various && bash run-test.sh
 	+cd tests/sat && bash run-test.sh
 	+cd tests/svinterfaces && bash run-test.sh $(SEEDOPT)
+	+cd tests/proc && bash run-test.sh
 	+cd tests/opt && bash run-test.sh
 	+cd tests/aiger && bash run-test.sh $(ABCOPT)
 	+cd tests/arch && bash run-test.sh

passes/proc/proc_clean.cc

@@ -69,8 +69,7 @@ void proc_clean_switch(RTLIL::SwitchRule *sw, RTLIL::CaseRule *parent, bool &did
 		did_something = true;
 		for (auto &action : sw->cases[0]->actions)
 			parent->actions.push_back(action);
-		for (auto sw2 : sw->cases[0]->switches)
-			parent->switches.push_back(sw2);
+		parent->switches.insert(parent->switches.begin(), sw->cases[0]->switches.begin(), sw->cases[0]->switches.end());
 		sw->cases[0]->switches.clear();
 		delete sw->cases[0];
 		sw->cases.clear();

tests/proc/.gitignore

@@ -0,0 +1 @@
+*.log

tests/proc/bug_1268.v

@@ -0,0 +1,23 @@
+module gold (input clock, ctrl, din, output reg dout);
+	always @(posedge clock) begin
+		if (1'b1) begin
+			if (1'b0) begin end else begin
+				dout <= 0;
+			end
+			if (ctrl)
+				dout <= din;
+		end
+	end
+endmodule
+
+module gate (input clock, ctrl, din, output reg dout);
+	always @(posedge clock) begin
+		if (1'b1) begin
+			if (1'b0) begin end else begin
+				dout <= 0;
+			end
+		end
+		if (ctrl)
+			dout <= din;
+	end
+endmodule

tests/proc/bug_1268.ys

@@ -0,0 +1,5 @@
+read_verilog bug_1268.v
+proc
+equiv_make gold gate equiv
+equiv_induct
+equiv_status -assert

tests/proc/run-test.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+set -e
+for x in *.ys; do
+  echo "Running $x.."
+  ../../yosys -ql ${x%.ys}.log $x
+done