Merge pull request #1070 from diffblue/sva-weak-strong

BMC: implement weak/strong sequences

Author: kroening

CHANGELOG

@@ -9,6 +9,7 @@
 * SystemVerilog: within
 * SystemVerilog: bugfix for |-> and |=>
 * SystemVerilog: bugfix for SVA sequence and
+* SystemVerilog: strong/weak sequence semantics
 * Verilog: 'dx, 'dz
 * SMV: LTL V operator, xnor operator
 * SMV: word types and operators

regression/verilog/SVA/cover_sequence2.desc

@@ -1,11 +1,12 @@
-KNOWNBUG
+CORE
 cover_sequence2.sv
---bound 2
-^\[main\.p0\] cover \(main\.x == 2 ##1 main\.x == 3 ##1 main\.x == 100\): PROVED$
-^\[main\.p1\] cover \(main\.x == 98 ##1 main\.x == 99 ##1 main\.x == 100\): REFUTED up to bound 2$
+--bound 5
+^\[main\.p0\] cover \(main\.x == 2 ##1 main\.x == 3 ##1 main\.x == 100\): REFUTED up to bound 5$
+^\[main\.p1\] cover \(main\.x == 98 ##1 main\.x == 99 ##1 main\.x == 100\): REFUTED up to bound 5$
+^\[main\.p2\] cover \(main\.x == 3 ##1 main\.x == 4 ##1 main\.x == 5\): PROVED$
+^\[main\.p3\] cover \(main\.x == 4 ##1 main\.x == 5 ##1 main\.x == 6\): REFUTED up to bound 5$
 ^EXIT=10$
 ^SIGNAL=0$
 --
 ^warning: ignoring
 --
-Cover property p0 cannot ever hold, but is shown proven when using a small bound.

regression/verilog/SVA/cover_sequence2.sv

@@ -1,15 +1,21 @@
 module main(input clk);
 
   // count up
-  reg [7:0] x = 0;
+  int x = 0;
 
-  always @(posedge clk)
+  always_ff @(posedge clk)
     x++;
 
   // expected to fail
   p0: cover property (x==2 ##1 x==3 ##1 x==100);
 
-  // expected to fail until bound reaches 100
+  // expected to fail until x reaches 100
   p1: cover property (x==98 ##1 x==99 ##1 x==100);
 
+  // expected to pass once x reaches 5
+  p2: cover property (x==3 ##1 x==4 ##1 x==5);
+
+  // expected to pass once x reaches 6
+  p3: cover property (x==4 ##1 x==5 ##1 x==6);
+
 endmodule

regression/verilog/SVA/cover_sequence3.desc

@@ -0,0 +1,11 @@
+CORE
+cover_sequence3.sv
+--bound 3
+^\[main\.p0\] cover \(1 \[\*10\]\): REFUTED up to bound 3$
+^\[main\.p1\] cover \(1 \[\*4:10\]\): PROVED$
+^\[main\.p2\] cover \(1 \[\*5:10\]\): REFUTED up to bound 3$
+^EXIT=10$
+^SIGNAL=0$
+--
+^warning: ignoring
+--

regression/verilog/SVA/cover_sequence3.sv

@@ -0,0 +1,18 @@
+module main(input clk);
+
+  // count up
+  int x = 0;
+
+  always_ff @(posedge clk)
+    x++;
+
+  // passes with bound >=9
+  p0: cover property (1[*10]);
+
+  // passes with bound >=3
+  p1: cover property (1[*4:10]);
+
+  // passes with bound >=4
+  p2: cover property (1[*5:10]);
+
+endmodule

regression/verilog/SVA/cover_sequence4.desc

@@ -0,0 +1,12 @@
+KNOWNBUG
+cover_sequence4.sv
+--bound 3
+^\[main\.p0\] cover \(1 \[=10\]\): REFUTED up to bound 3$
+^\[main\.p1\] cover \(1 \[=4:10\]\): PROVED$
+^\[main\.p2\] cover \(1 \[=5:10\]\): REFUTED up to bound 3$
+^EXIT=10$
+^SIGNAL=0$
+--
+^warning: ignoring
+--
+Implementation of [=x:y] is missing.

regression/verilog/SVA/cover_sequence4.sv

@@ -0,0 +1,18 @@
+module main(input clk);
+
+  // count up
+  int x = 0;
+
+  always_ff @(posedge clk)
+    x++;
+
+  // passes with bound >=9
+  p0: cover property (1[=10]);
+
+  // passes with bound >=3
+  p1: cover property (1[=4:10]);
+
+  // passes with bound >=4
+  p2: cover property (1[=5:10]);
+
+endmodule

regression/verilog/SVA/sequence2.desc

@@ -1,11 +1,10 @@
-KNOWNBUG
+CORE
 sequence2.sv
---bound 10 --numbered-trace
-^\[main\.p0] ##\[0:\$\] main\.x == 10: PROVED up to bound 10$
-^\[main\.p1] ##\[0:\$\] main\.x == 10: REFUTED$
+--bound 10
+^\[main\.p0] weak\(##\[0:\$\] main\.x == 10\): PROVED up to bound 10$
+^\[main\.p1] strong\(##\[0:\$\] main\.x == 10\): REFUTED$
 ^EXIT=10$
 ^SIGNAL=0$
 --
 ^warning: ignoring
 --
-strong(...) is missing.

regression/verilog/SVA/sequence3.desc

@@ -1,13 +1,12 @@
-KNOWNBUG
+CORE
 sequence3.sv
 --bound 20 --numbered-trace
-^\[main\.p0\] ##\[\*\] main\.x == 6: REFUTED$
-^\[main\.p1\] ##\[\*\] main\.x == 5: PROVED up to bound 20$
-^\[main\.p2\] ##\[\+\] main\.x == 0: REFUTED$
-^\[main\.p3\] ##\[\+\] main\.x == 5: PROVED up to bound 20$
+^\[main\.p0\] strong\(##\[\*\] main\.x == 6\): REFUTED$
+^\[main\.p1\] strong\(##\[\*\] main\.x == 5\): PROVED up to bound 20$
+^\[main\.p2\] strong\(##\[\+\] main\.x == 0\): REFUTED$
+^\[main\.p3\] strong\(##\[\+\] main\.x == 5\): PROVED up to bound 20$
 ^EXIT=10$
 ^SIGNAL=0$
 --
 ^warning: ignoring
 --
-strong(...) is missing

regression/verilog/SVA/strong1.desc

@@ -1,7 +1,7 @@
 CORE
 strong1.sv
---bound 20
-^\[main\.p0\] strong\(##\[0:9\] main\.x == 100\): REFUTED$
+--bound 4
+^\[main\.p0\] strong\(##\[0:9\] main\.x == 5\): REFUTED$
 ^EXIT=10$
 ^SIGNAL=0$
 --