From ccf39099826b7160d1283766bbaee19d48c8dd2e Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 03:28:50 -0700
Subject: [PATCH 1/8] Initial implementation of addsub_c with no intermediate
 fanout allowed

---
 passes/opt/Makefile.inc         |   1 +
 passes/opt/peepopt.cc           |   3 +
 passes/opt/peepopt_addsub_c.pmg | 129 +++++
 tests/peepopt/addsub_c.ys       | 954 ++++++++++++++++++++++++++++++++
 4 files changed, 1087 insertions(+)
 create mode 100644 passes/opt/peepopt_addsub_c.pmg
 create mode 100644 tests/peepopt/addsub_c.ys

diff --git a/passes/opt/Makefile.inc b/passes/opt/Makefile.inc
index c388bb8da..96566c588 100644
--- a/passes/opt/Makefile.inc
+++ b/passes/opt/Makefile.inc
@@ -33,6 +33,7 @@ PEEPOPT_PATTERN += passes/opt/peepopt_shiftmul_left.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_shiftadd.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_muldiv.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_muldiv_c.pmg
+PEEPOPT_PATTERN += passes/opt/peepopt_addsub_c.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_muxorder.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_formal_clockgateff.pmg
 PEEPOPT_PATTERN += passes/opt/peepopt_sub_neg.pmg
diff --git a/passes/opt/peepopt.cc b/passes/opt/peepopt.cc
index c2597cbfc..1ef160191 100644
--- a/passes/opt/peepopt.cc
+++ b/passes/opt/peepopt.cc
@@ -51,6 +51,8 @@ struct PeepoptPass : public Pass {
 		log("\n");
 		log("This pass employs the following rules by default:\n");
 		log("\n");
+		log("   * addsub_c - Replace (A+-B)+-C with A+(B+-C) when B and C are constants.\n");
+		log("\n");
 		log("   * muldiv - Replace (A*B)/B with A\n");
 		log("\n");
 		log("   * muldiv_c - Replace (A*B)/C with A*(B/C) when C is a const divisible by B.\n");
@@ -127,6 +129,7 @@ struct PeepoptPass : public Pass {
 					pm.run_shiftmul_left();
 					pm.run_muldiv();
 					pm.run_muldiv_c();
+					pm.run_addsub_c();
 					pm.run_sub_neg();
 					if (muxorder)
 						pm.run_muxorder();
diff --git a/passes/opt/peepopt_addsub_c.pmg b/passes/opt/peepopt_addsub_c.pmg
new file mode 100644
index 000000000..29e5a4741
--- /dev/null
+++ b/passes/opt/peepopt_addsub_c.pmg
@@ -0,0 +1,129 @@
+pattern addsub_c
+//
+// Authored by Akash Levy of Silimate, Inc. under ISC license.
+// Transforms add->add/sub_c into add_c canceling the constants out:
+// y = (a +- b_const) +- c_const   ===>   a +- eval(b_const +- c_const)
+//
+
+state <SigSpec> a b_const addsub1_y
+
+match addsub1
+	// Select add/sub
+	select addsub1->type.in($add, $sub)
+endmatch
+
+code a b_const addsub1_y
+	// Get adder signals
+	a = port(addsub1, \A);
+	b_const = port(addsub1, \B);
+	addsub1_y = port(addsub1, \Y);
+
+	// Fanout of each add/sub Y bit should be 1 (no bit-split)
+	if (nusers(addsub1_y) != 2)
+		reject;
+
+	// A and B can be interchanged for adder
+	if (addsub1->type == $add) {
+		branch;
+		std::swap(a, b_const);
+	}
+endcode
+
+match addsub2
+	// Select add/sub of form (a +- b_const) +- c_const
+	select addsub2->type.in($add, $sub)
+
+	// Check that b_const and c_const is constant
+	filter b_const.is_fully_const()
+	filter port(addsub2, \B).is_fully_const()
+	index <SigSpec> remove_bottom_padding(port(addsub2, \A)) === addsub1_y
+endmatch
+
+code
+	// Get addsub2 signals
+	SigSpec addsub2_a = port(addsub2, \A);
+	SigSpec c_const = port(addsub2, \B);
+	SigSpec addsub2_y = port(addsub2, \Y);
+
+	// Get offset of addsub1 result chunk in addsub2
+	int offset = GetSize(addsub2_a) - GetSize(addsub1_y);
+
+	// Get properties and values of b_const and c_const
+	// b_const may be coming from the A port
+	// But it is an RTLIL invariant that A_SIGNED equals B_SIGNED
+	bool b_const_signed = addsub1->getParam(ID::B_SIGNED).as_bool();
+	bool c_const_signed = addsub2->getParam(ID::B_SIGNED).as_bool();
+	int b_const_int = b_const.as_int(b_const_signed);
+	int c_const_int = c_const.as_int(c_const_signed);
+	int b_const_int_shifted = b_const_int << offset;
+
+	// Helper lambdas for two's complement math	
+	auto sign2sComplement = [](auto value, int numBits) {
+  		if (value & (1 << (numBits - 1))) {
+   			return -1; 
+  		} else {
+   		    return 1; 
+  		}
+	};
+	auto twosComplement = [](auto value, int numBits) {
+  		if (value & (1 << (numBits - 1))) {
+   			return (~value) + 1; // invert bits before adding 1
+  		} else {
+   		    return value; 
+  		}
+	};
+
+	// Two's complement conversion
+	if (b_const_signed)
+		b_const_int = sign2sComplement(b_const_int, GetSize(b_const)) * twosComplement(b_const_int, GetSize(b_const));
+	if (c_const_signed)
+		c_const_int = sign2sComplement(c_const_int, GetSize(c_const)) * twosComplement(c_const_int, GetSize(c_const));
+	// Calculate the constant and compress the width to fit the value
+	Const const_value;
+	Const b_const_actual;
+	b_const_actual = b_const_int_shifted;
+	b_const_actual.compress(b_const_signed);
+
+	if (addsub1->type == $add)
+		if (addsub2->type == $add)
+			const_value = b_const_int_shifted + c_const_int;
+		else
+			const_value = b_const_int_shifted - c_const_int;
+	else
+		if (addsub2->type == $add)
+			const_value = b_const_int_shifted - c_const_int;
+		else
+			const_value = b_const_int_shifted + c_const_int;
+	const_value.compress(b_const_signed | c_const_signed);
+
+	// Integer values should be lesser than 32 bits
+	// This is because we are using C++ types, and int is 32 bits
+	// FIXME: use long long or BigInteger to make pass work with >32 bits
+	if (GetSize(addsub1->getParam(ID::B_WIDTH)) > 32)
+		reject;
+	if (GetSize(b_const) > 32)
+		reject;
+	if (GetSize(c_const) + offset > 32)
+		reject;
+
+	// // Check for potential overflow
+	// if (std::max(GetSize(b_const_actual), GetSize(a)) + 1 > GetSize(addsub1_y))
+	// 	reject;
+
+	// Check that there are only zeros before offset
+	if (offset < 0 || !addsub2_a.extract(0, offset).is_fully_zero())
+		reject;
+
+	// Rewire to only keep addsub1
+	addsub1->setPort(\A, a);
+	addsub1->setPort(\B, const_value);
+	addsub1->setPort(\Y, addsub2_y);
+
+	// Remove addsub2
+	autoremove(addsub2);
+
+	// Log, fixup, accept
+	log("addsub_const pattern in %s: addsub1=%s, addsub2=%s\n", log_id(module), log_id(addsub1), log_id(addsub2));
+	addsub1->fixup_parameters();
+	accept;
+endcode
diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
new file mode 100644
index 000000000..e8b8733cf
--- /dev/null
+++ b/tests/peepopt/addsub_c.ys
@@ -0,0 +1,954 @@
+log -header "Test simple positive case 1"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [31:0] a,
+  output wire  [31:0] y
+);
+  assign y = a + 1023 + 127;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Test simple positive case 2"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [31:0] a,
+  output wire  [31:0] y
+);
+  assign y = a + 1023 - 127;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Test simple positive case 3"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [31:0] a,
+  output wire  [31:0] y
+);
+  assign y = a - 1023 + 127;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 0
+select t:$sub -assert-count 1
+design -reset
+log -pop
+
+log -header "Test simple positive case 4"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [31:0] a,
+  output wire  [31:0] y
+);
+  assign y = a - 1023 - 127;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 0
+select t:$sub -assert-count 1
+design -reset
+log -pop
+
+
+
+log -header "Signed pattern transformed: (a +- b) +- c case 1"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Signed pattern transformed: (a +- b) +- c case 2"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Signed pattern transformed: (a +- b) +- c case 3"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "Signed pattern transformed: (a +- b) +- c case 3"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+
+
+log -header "Symmetry case 1"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = 4'sd6 + a;
+	assign y = add + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Symmetry case 2"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = 4'sd6 + a;
+	assign y = add - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Symmetry case 3: no transformation since constant is first"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = 4'sd6 - a;
+	assign y = sub + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "Symmetry case 4: no transformation since constant is first"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = 4'sd6 - a;
+	assign y = sub - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 2 t:$sub
+design -reset
+log -pop
+
+
+
+log -header "Transformed on b == c case 1"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add + 8'sd6;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Transformed on b == c case 2"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add - 8'sd6;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "Transformed on b == c case 3"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub + 8'sd6;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "Transformed on b == c case 4"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub - 8'sd6;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+
+
+log -header "b negative, c positive case 1"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + (-4'sd6);
+	assign y = add + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "b negative, c positive case 2"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] add;
+	assign add = a + (-4'sd6);
+	assign y = add - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "b negative, c positive case 3"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - (-4'sd6);
+	assign y = sub + 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "b negative, c positive case 4"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+);
+	wire signed [7:0] sub;
+	assign sub = a - (-4'sd6);
+	assign y = sub - 8'sd3;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+
+
+log -header "No transform when addsub1 has a second fanout case 1"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+	output signed [7:0] z,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add + 8'sd3;
+	assign z = add;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 2 t:$add
+select -assert-count 0 t:$sub
+design -reset
+log -pop
+
+log -header "No transform when addsub1 has a second fanout case 2"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+	output signed [7:0] z,
+);
+	wire signed [7:0] add;
+	assign add = a + 4'sd6;
+	assign y = add - 8'sd3;
+	assign z = add;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "No transform when addsub1 has a second fanout case 3"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+	output signed [7:0] z,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub + 8'sd3;
+	assign z = sub;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 1 t:$add
+select -assert-count 1 t:$sub
+design -reset
+log -pop
+
+log -header "No transform when addsub1 has a second fanout case 4"
+log -push
+read_verilog <<EOT
+module top(
+	input signed [3:0] a,
+	output signed [7:0] y,
+	output signed [7:0] z,
+);
+	wire signed [7:0] sub;
+	assign sub = a - 4'sd6;
+	assign y = sub - 8'sd3;
+	assign z = sub;
+endmodule
+EOT
+equiv_opt -assert peepopt
+design -load postopt
+select -assert-count 0 t:$add
+select -assert-count 2 t:$sub
+design -reset
+log -pop
+
+
+
+# =============================================================================
+# OVERFLOW TESTS
+# =============================================================================
+
+log -header "Overflow test: unsigned 4-bit max value + constant"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [3:0] a,
+  output wire  [7:0] y
+);
+  assign y = a + 4'd15 + 4'd1;  // 15 + 1 = 16 (overflows 4-bit but not 7-bit)
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Overflow test: signed 4-bit max value + constant"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input signed [3:0] a,
+  output signed [7:0] y
+);
+  assign y = a + 4'sd7 + 4'sd1;  // 7 + 1 = 8 (overflows 4-bit signed but not 7-bit)
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Overflow test: negative signed constants"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input signed [3:0] a,
+  output signed [7:0] y
+);
+  assign y = a + (-4'sd8) + (-4'sd1);  // -8 + (-1) = -9 (underflows 4-bit signed but not 7-bit)
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Large constant test: 32-bit constants"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [31:0] a,
+  output wire  [31:0] y
+);
+  assign y = a + 32'h7FFFFFFF + 32'h1;  // Large positive constants
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+# =============================================================================
+# SIGNEDNESS MIXING TESTS
+# =============================================================================
+
+log -header "Mixed signedness: unsigned input with signed constants"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output signed [15:0] y
+);
+  wire signed [15:0] temp;
+  assign temp = a + 8'sd10;
+  assign y = temp + 16'sd5;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Mixed signedness: signed input with unsigned constants"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input signed [7:0] a,
+  output wire [15:0] y
+);
+  wire [15:0] temp;
+  assign temp = a + 8'd10;
+  assign y = temp + 16'd5;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+# =============================================================================
+# DRIVING OTHER OPERATIONS TESTS
+# =============================================================================
+
+log -header "Result drives multiplication"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  input wire  [7:0] b,
+  output wire  [15:0] y
+);
+  wire [7:0] temp;
+  assign temp = a + 8'd10 + 8'd5;
+  assign y = temp * b;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+select t:$mul -assert-count 1
+design -reset
+log -pop
+
+log -header "Result drives comparison"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  y
+);
+  wire [7:0] temp;
+  assign temp = a + 8'd10 + 8'd5;
+  assign y = temp > 8'd100;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+select t:$gt -assert-count 1
+design -reset
+log -pop
+
+log -header "Result drives logical operations"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  input wire  [7:0] b,
+  output wire  [7:0] y
+);
+  wire [7:0] temp;
+  assign temp = a + 8'd10 + 8'd5;
+  assign y = temp & b;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+select t:$and -assert-count 1
+design -reset
+log -pop
+
+log -header "Result drives shift operation"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  wire [7:0] temp;
+  assign temp = a + 8'd10 + 8'd5;
+  assign y = temp << 2;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+select t:$shl -assert-count 1
+design -reset
+log -pop
+
+# =============================================================================
+# WEIRD STRUCTURES AND EDGE CASES
+# =============================================================================
+
+log -header "Zero constant optimization"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  assign y = a + 8'd10 + 8'd0;  // Should optimize to just a + 10
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Constants that cancel out"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  assign y = a + 8'd10 - 8'd10;  // Should optimize to just a
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+# After optimization, this should either be no operations or just a wire connection
+design -reset
+log -pop
+
+log -header "Triple chained operations (optimizes fully)"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  wire [7:0] temp1, temp2;
+  assign temp1 = a + 8'd5;
+  assign temp2 = temp1 + 8'd10;
+  assign y = temp2 + 8'd3;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+# The optimization actually works on multiple levels
+select t:$add -assert-count 1  // Optimizes to single add (a + 18)
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Different bit widths in chain"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [4:0] a,
+  output wire  [15:0] y
+);
+  wire [10:0] temp;
+  assign temp = a + 5'd10;
+  assign y = temp + 11'd500;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Negative result from subtraction chain"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input signed [7:0] a,
+  output signed [7:0] y
+);
+  assign y = a - 8'sd100 - 8'sd50;  // Should result in a - 150
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 0
+select t:$sub -assert-count 1
+design -reset
+log -pop
+
+log -header "Mixed add/sub with large intermediate result"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [15:0] y
+);
+  wire [15:0] temp;
+  assign temp = a + 8'd255;
+  assign y = temp - 16'd100;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Single bit operations"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  a,
+  output wire  [7:0] y
+);
+  wire [7:0] temp;
+  assign temp = a + 1'd1;
+  assign y = temp + 8'd5;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Constants with different representations (hex, decimal, binary)"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  assign y = a + 8'hFF + 8'b00000001;  // 255 + 1 = 256 (overflows to 0 in 8-bit)
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+# =============================================================================
+# CORNER CASES FOR PATTERN MATCHING
+# =============================================================================
+
+log -header "Constants in A position (commutative add)"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [7:0] a,
+  output wire  [7:0] y
+);
+  wire [7:0] temp;
+  assign temp = 8'd10 + a;  // Constant first
+  assign y = temp + 8'd5;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Very small bit widths"
+log -push
+design -reset
+read_verilog <<EOF
+module top (
+  input wire  [1:0] a,
+  output wire  [3:0] y
+);
+  wire [3:0] temp;
+  assign temp = a + 2'd1;
+  assign y = temp + 4'd2;
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Test with parameters/generics"
+log -push
+design -reset
+read_verilog <<EOF
+module top #(parameter WIDTH = 8) (
+  input wire  [WIDTH-1:0] a,
+  output wire  [WIDTH+2:0] y
+);
+  wire [WIDTH+2:0] temp;
+  assign temp = a + 5;
+  assign y = temp + 3;
+endmodule
+EOF
+check -assert
+wreduce
+equiv_opt -assert peepopt
+design -load postopt
+select t:$add -assert-count 1
+select t:$sub -assert-count 0
+design -reset
+log -pop
+
+log -header "Final test case"
+log -push
+design -reset
+read_verilog -sv <<EOF
+module top (
+	input logic [7:0] var_exp_a,
+	input logic var_zero_a,
+	input logic var_inf_a,
+	output logic var_zero_ac,
+	output logic var_inf_ac,
+	output logic signed [11:0] var_exp_ac
+);
+  assign var_exp_ac = $signed({1'b0, var_exp_a}) - 1023 + 127;
+	assign var_zero_ac = var_zero_a | (var_exp_ac <= 0);
+	assign var_inf_ac = var_inf_a | (var_exp_ac >= 255);
+endmodule
+EOF
+check -assert
+equiv_opt -assert peepopt
+design -load postopt
+write_verilog test.v
+select t:$add -assert-count 0
+select t:$sub -assert-count 1
+design -reset
+log -pop

From c1557950ef57bbfbcabe5ddfed5bc941cd9d2938 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 03:48:14 -0700
Subject: [PATCH 2/8] Support external fanout for addsub_c

---
 passes/opt/peepopt_addsub_c.pmg | 22 +++++++++++++---------
 tests/peepopt/addsub_c.ys       | 17 ++++++++---------
 2 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/passes/opt/peepopt_addsub_c.pmg b/passes/opt/peepopt_addsub_c.pmg
index 29e5a4741..f2aadcfed 100644
--- a/passes/opt/peepopt_addsub_c.pmg
+++ b/passes/opt/peepopt_addsub_c.pmg
@@ -18,10 +18,6 @@ code a b_const addsub1_y
 	b_const = port(addsub1, \B);
 	addsub1_y = port(addsub1, \Y);
 
-	// Fanout of each add/sub Y bit should be 1 (no bit-split)
-	if (nusers(addsub1_y) != 2)
-		reject;
-
 	// A and B can be interchanged for adder
 	if (addsub1->type == $add) {
 		branch;
@@ -40,6 +36,9 @@ match addsub2
 endmatch
 
 code
+  // New addsub1 cell (will be reused unless there is external fanout)
+	auto cell = addsub1;
+
 	// Get addsub2 signals
 	SigSpec addsub2_a = port(addsub2, \A);
 	SigSpec c_const = port(addsub2, \B);
@@ -114,16 +113,21 @@ code
 	if (offset < 0 || !addsub2_a.extract(0, offset).is_fully_zero())
 		reject;
 
-	// Rewire to only keep addsub1
-	addsub1->setPort(\A, a);
-	addsub1->setPort(\B, const_value);
-	addsub1->setPort(\Y, addsub2_y);
+	// Reuse/create new cell to drive the rewritten equation
+	if (nusers(addsub1_y) != 2) {
+		cell = module->addCell(NEW_ID2_SUFFIX("asconst"), addsub1->type);
+		cell->attributes = addsub1->attributes;
+		cell->parameters = addsub1->parameters;
+	}
+	cell->setPort(\A, a);
+	cell->setPort(\B, const_value);
+	cell->setPort(\Y, addsub2_y);
 
 	// Remove addsub2
 	autoremove(addsub2);
 
 	// Log, fixup, accept
 	log("addsub_const pattern in %s: addsub1=%s, addsub2=%s\n", log_id(module), log_id(addsub1), log_id(addsub2));
-	addsub1->fixup_parameters();
+	cell->fixup_parameters();
 	accept;
 endcode
diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
index e8b8733cf..c0934dd4b 100644
--- a/tests/peepopt/addsub_c.ys
+++ b/tests/peepopt/addsub_c.ys
@@ -388,7 +388,7 @@ log -pop
 
 
 
-log -header "No transform when addsub1 has a second fanout case 1"
+log -header "Transform even when addsub1 has a second fanout case 1"
 log -push
 read_verilog <<EOT
 module top(
@@ -409,7 +409,7 @@ select -assert-count 0 t:$sub
 design -reset
 log -pop
 
-log -header "No transform when addsub1 has a second fanout case 2"
+log -header "Transform even when addsub1 has a second fanout case 2"
 log -push
 read_verilog <<EOT
 module top(
@@ -425,12 +425,12 @@ endmodule
 EOT
 equiv_opt -assert peepopt
 design -load postopt
-select -assert-count 1 t:$add
-select -assert-count 1 t:$sub
+select -assert-count 2 t:$add
+select -assert-count 0 t:$sub
 design -reset
 log -pop
 
-log -header "No transform when addsub1 has a second fanout case 3"
+log -header "Transform even when addsub1 has a second fanout case 3"
 log -push
 read_verilog <<EOT
 module top(
@@ -446,12 +446,12 @@ endmodule
 EOT
 equiv_opt -assert peepopt
 design -load postopt
-select -assert-count 1 t:$add
-select -assert-count 1 t:$sub
+select -assert-count 0 t:$add
+select -assert-count 2 t:$sub
 design -reset
 log -pop
 
-log -header "No transform when addsub1 has a second fanout case 4"
+log -header "Transform even when addsub1 has a second fanout case 4"
 log -push
 read_verilog <<EOT
 module top(
@@ -947,7 +947,6 @@ EOF
 check -assert
 equiv_opt -assert peepopt
 design -load postopt
-write_verilog test.v
 select t:$add -assert-count 0
 select t:$sub -assert-count 1
 design -reset

From 54a1862fbed19dbea370de0ea6c8a0cbe3274928 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Thu, 11 Sep 2025 04:32:18 -0700
Subject: [PATCH 3/8] Apply suggestions from code review

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
---
 tests/peepopt/addsub_c.ys | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
index c0934dd4b..6543de7cf 100644
--- a/tests/peepopt/addsub_c.ys
+++ b/tests/peepopt/addsub_c.ys
@@ -133,7 +133,7 @@ select -assert-count 1 t:$sub
 design -reset
 log -pop
 
-log -header "Signed pattern transformed: (a +- b) +- c case 3"
+log -header "Signed pattern transformed: (a +- b) +- c case 4"
 log -push
 read_verilog <<EOT
 module top(
@@ -753,7 +753,7 @@ check -assert
 equiv_opt -assert peepopt
 design -load postopt
 # The optimization actually works on multiple levels
-select t:$add -assert-count 1  // Optimizes to single add (a + 18)
+select t:$add -assert-count 1  # Optimizes to single add (a + 18)
 select t:$sub -assert-count 0
 design -reset
 log -pop

From b70aeea35cefca5c41a5b3a43b1257cc37e64912 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 04:37:00 -0700
Subject: [PATCH 4/8] Fixups

---
 passes/opt/peepopt_addsub_c.pmg | 49 ++++-----------------------------
 1 file changed, 6 insertions(+), 43 deletions(-)

diff --git a/passes/opt/peepopt_addsub_c.pmg b/passes/opt/peepopt_addsub_c.pmg
index f2aadcfed..76c6bd74f 100644
--- a/passes/opt/peepopt_addsub_c.pmg
+++ b/passes/opt/peepopt_addsub_c.pmg
@@ -32,7 +32,7 @@ match addsub2
 	// Check that b_const and c_const is constant
 	filter b_const.is_fully_const()
 	filter port(addsub2, \B).is_fully_const()
-	index <SigSpec> remove_bottom_padding(port(addsub2, \A)) === addsub1_y
+	index <SigSpec> port(addsub2, \A) === addsub1_y
 endmatch
 
 code
@@ -44,9 +44,6 @@ code
 	SigSpec c_const = port(addsub2, \B);
 	SigSpec addsub2_y = port(addsub2, \Y);
 
-	// Get offset of addsub1 result chunk in addsub2
-	int offset = GetSize(addsub2_a) - GetSize(addsub1_y);
-
 	// Get properties and values of b_const and c_const
 	// b_const may be coming from the A port
 	// But it is an RTLIL invariant that A_SIGNED equals B_SIGNED
@@ -54,45 +51,19 @@ code
 	bool c_const_signed = addsub2->getParam(ID::B_SIGNED).as_bool();
 	int b_const_int = b_const.as_int(b_const_signed);
 	int c_const_int = c_const.as_int(c_const_signed);
-	int b_const_int_shifted = b_const_int << offset;
 
-	// Helper lambdas for two's complement math	
-	auto sign2sComplement = [](auto value, int numBits) {
-  		if (value & (1 << (numBits - 1))) {
-   			return -1; 
-  		} else {
-   		    return 1; 
-  		}
-	};
-	auto twosComplement = [](auto value, int numBits) {
-  		if (value & (1 << (numBits - 1))) {
-   			return (~value) + 1; // invert bits before adding 1
-  		} else {
-   		    return value; 
-  		}
-	};
-
-	// Two's complement conversion
-	if (b_const_signed)
-		b_const_int = sign2sComplement(b_const_int, GetSize(b_const)) * twosComplement(b_const_int, GetSize(b_const));
-	if (c_const_signed)
-		c_const_int = sign2sComplement(c_const_int, GetSize(c_const)) * twosComplement(c_const_int, GetSize(c_const));
 	// Calculate the constant and compress the width to fit the value
 	Const const_value;
-	Const b_const_actual;
-	b_const_actual = b_const_int_shifted;
-	b_const_actual.compress(b_const_signed);
-
 	if (addsub1->type == $add)
 		if (addsub2->type == $add)
-			const_value = b_const_int_shifted + c_const_int;
+			const_value = b_const_int + c_const_int;
 		else
-			const_value = b_const_int_shifted - c_const_int;
+			const_value = b_const_int - c_const_int;
 	else
 		if (addsub2->type == $add)
-			const_value = b_const_int_shifted - c_const_int;
+			const_value = b_const_int - c_const_int;
 		else
-			const_value = b_const_int_shifted + c_const_int;
+			const_value = b_const_int + c_const_int;
 	const_value.compress(b_const_signed | c_const_signed);
 
 	// Integer values should be lesser than 32 bits
@@ -102,15 +73,7 @@ code
 		reject;
 	if (GetSize(b_const) > 32)
 		reject;
-	if (GetSize(c_const) + offset > 32)
-		reject;
-
-	// // Check for potential overflow
-	// if (std::max(GetSize(b_const_actual), GetSize(a)) + 1 > GetSize(addsub1_y))
-	// 	reject;
-
-	// Check that there are only zeros before offset
-	if (offset < 0 || !addsub2_a.extract(0, offset).is_fully_zero())
+	if (GetSize(c_const) > 32)
 		reject;
 
 	// Reuse/create new cell to drive the rewritten equation

From 8f5b20c423a70d9ce36acccb99e489f96427c8ce Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Thu, 11 Sep 2025 04:46:32 -0700
Subject: [PATCH 5/8] Apply suggestions from code review

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
---
 tests/peepopt/addsub_c.ys | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
index 6543de7cf..9a6a397cb 100644
--- a/tests/peepopt/addsub_c.ys
+++ b/tests/peepopt/addsub_c.ys
@@ -81,7 +81,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -100,7 +100,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -119,7 +119,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;
@@ -138,7 +138,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;
@@ -159,7 +159,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = 4'sd6 + a;

From b1f4d0d8aa202984fe16c9cefb5db6f7e1b53ca8 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 04:47:28 -0700
Subject: [PATCH 6/8] Small adjustments

---
 passes/opt/peepopt_addsub_c.pmg |  4 ++--
 tests/peepopt/addsub_c.ys       | 30 +++++++++++++++---------------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/passes/opt/peepopt_addsub_c.pmg b/passes/opt/peepopt_addsub_c.pmg
index 76c6bd74f..483fed4d1 100644
--- a/passes/opt/peepopt_addsub_c.pmg
+++ b/passes/opt/peepopt_addsub_c.pmg
@@ -1,7 +1,7 @@
 pattern addsub_c
 //
 // Authored by Akash Levy of Silimate, Inc. under ISC license.
-// Transforms add->add/sub_c into add_c canceling the constants out:
+// Transforms add->add/sub_c into add_c folding the constants:
 // y = (a +- b_const) +- c_const   ===>   a +- eval(b_const +- c_const)
 //
 
@@ -76,7 +76,7 @@ code
 	if (GetSize(c_const) > 32)
 		reject;
 
-	// Reuse/create new cell to drive the rewritten equation
+	// Reuse/create new cell to drive the folded expression
 	if (nusers(addsub1_y) != 2) {
 		cell = module->addCell(NEW_ID2_SUFFIX("asconst"), addsub1->type);
 		cell->attributes = addsub1->attributes;
diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
index 9a6a397cb..d8e09cc1e 100644
--- a/tests/peepopt/addsub_c.ys
+++ b/tests/peepopt/addsub_c.ys
@@ -178,7 +178,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = 4'sd6 + a;
@@ -197,7 +197,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = 4'sd6 - a;
@@ -216,7 +216,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = 4'sd6 - a;
@@ -237,7 +237,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -256,7 +256,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -275,7 +275,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;
@@ -294,7 +294,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;
@@ -315,7 +315,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + (-4'sd6);
@@ -334,7 +334,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] add;
 	assign add = a + (-4'sd6);
@@ -353,7 +353,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - (-4'sd6);
@@ -372,7 +372,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 );
 	wire signed [7:0] sub;
 	assign sub = a - (-4'sd6);
@@ -393,7 +393,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 	output signed [7:0] z,
 );
 	wire signed [7:0] add;
@@ -414,7 +414,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 	output signed [7:0] z,
 );
 	wire signed [7:0] add;
@@ -435,7 +435,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 	output signed [7:0] z,
 );
 	wire signed [7:0] sub;
@@ -456,7 +456,7 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y,
+	output signed [7:0] y
 	output signed [7:0] z,
 );
 	wire signed [7:0] sub;

From e25492e87aabe61421d4273d699a9bd4dd5475fd Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 04:50:58 -0700
Subject: [PATCH 7/8] Smallfixes

---
 tests/peepopt/addsub_c.ys | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tests/peepopt/addsub_c.ys b/tests/peepopt/addsub_c.ys
index d8e09cc1e..6a3888542 100644
--- a/tests/peepopt/addsub_c.ys
+++ b/tests/peepopt/addsub_c.ys
@@ -393,8 +393,8 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y
-	output signed [7:0] z,
+	output signed [7:0] y,
+	output signed [7:0] z
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -414,8 +414,8 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y
-	output signed [7:0] z,
+	output signed [7:0] y,
+	output signed [7:0] z
 );
 	wire signed [7:0] add;
 	assign add = a + 4'sd6;
@@ -435,8 +435,8 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y
-	output signed [7:0] z,
+	output signed [7:0] y,
+	output signed [7:0] z
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;
@@ -456,8 +456,8 @@ log -push
 read_verilog <<EOT
 module top(
 	input signed [3:0] a,
-	output signed [7:0] y
-	output signed [7:0] z,
+	output signed [7:0] y,
+	output signed [7:0] z
 );
 	wire signed [7:0] sub;
 	assign sub = a - 4'sd6;

From f39d78c69f6037a2b749976b01d42ccd58ba0b35 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 11 Sep 2025 05:02:58 -0700
Subject: [PATCH 8/8] Smallfixes

---
 passes/opt/peepopt_addsub_c.pmg | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/passes/opt/peepopt_addsub_c.pmg b/passes/opt/peepopt_addsub_c.pmg
index 483fed4d1..9002d55b7 100644
--- a/passes/opt/peepopt_addsub_c.pmg
+++ b/passes/opt/peepopt_addsub_c.pmg
@@ -36,11 +36,10 @@ match addsub2
 endmatch
 
 code
-  // New addsub1 cell (will be reused unless there is external fanout)
+	// New addsub1 cell (will be reused unless there is external fanout)
 	auto cell = addsub1;
 
 	// Get addsub2 signals
-	SigSpec addsub2_a = port(addsub2, \A);
 	SigSpec c_const = port(addsub2, \B);
 	SigSpec addsub2_y = port(addsub2, \Y);
 
@@ -69,7 +68,13 @@ code
 	// Integer values should be lesser than 32 bits
 	// This is because we are using C++ types, and int is 32 bits
 	// FIXME: use long long or BigInteger to make pass work with >32 bits
-	if (GetSize(addsub1->getParam(ID::B_WIDTH)) > 32)
+	if (addsub1->getParam(ID::A_WIDTH).as_int() > 32)
+		reject;
+	if (addsub1->getParam(ID::B_WIDTH).as_int() > 32)
+		reject;
+	if (addsub2->getParam(ID::A_WIDTH).as_int() > 32)
+		reject;
+	if (addsub2->getParam(ID::B_WIDTH).as_int() > 32)
 		reject;
 	if (GetSize(b_const) > 32)
 		reject;