Add a constant folding pass after inlining (#4727)

* Add a constant folding pass after inlining

Signed-off-by: Mihai Budiu <mbudiu@feldera.com>

* Updated reference outputs

Signed-off-by: Mihai Budiu <mbudiu@feldera.com>

---------

Signed-off-by: Mihai Budiu <mbudiu@feldera.com>

frontends/p4/frontend.cpp

@@ -252,6 +252,7 @@ const IR::P4Program *FrontEnd::run(const CompilerOptions &options, const IR::P4P
             new SetHeaders(&refMap, &typeMap),
             // Check for constants only after inlining
             new CheckConstants(&refMap, &typeMap),
+            new ConstantFolding(&refMap, &typeMap, constantFoldingPolicy),
             new SimplifyControlFlow(&refMap, &typeMap),
             // more ifs may have been added to parsers
             new RemoveParserControlFlow(&refMap, &typeMap),

testdata/p4_16_samples/issue4548.p4

@@ -0,0 +1,20 @@
+#include <core.p4>
+
+bit<16> fun1(bit<8> args1) {
+    return (bit<16>)args1;
+}
+bit<8> fun2(bit<4> args2) {
+    fun1(8w10);
+    return 8w0;
+}
+
+control ingress() {
+    apply {
+        fun2(4w3);
+        fun2(4w3);
+    }
+}
+
+control Ingress();
+package top( Ingress ig);
+top( ingress()) main;

testdata/p4_16_samples_outputs/gauntlet_hdr_in_value-bmv2-frontend.p4

@@ -25,7 +25,7 @@ parser p(packet_in pkt, out Headers hdr, inout Meta m, inout standard_metadata_t
 control ingress(inout Headers h, inout Meta m, inout standard_metadata_t sm) {
     @name("ingress.retval") bit<16> retval;
     apply {
-        retval = ((Headers){eth_hdr = (ethernet_t){dst_addr = 48w1,src_addr = 48w1,eth_type = 16w1}}).eth_hdr.eth_type + 16w1;
+        retval = 16w2;
         h.eth_hdr.eth_type = retval;
     }
 }

testdata/p4_16_samples_outputs/issue1638-frontend.p4

@@ -24,7 +24,7 @@ control MyC(inout hdr_t hdr, inout meta_t meta, in intrinsic_metadata_t intr_md)
     }
     @name("MyC.c2.a") table c2_a {
         key = {
-            ((meta_t){f0 = 8w0,f1 = 8w0,f2 = 8w0}).f0: exact @name("meta.f0");
+            8w0: exact @name("meta.f0");
         }
         actions = {
             NoAction_1();

testdata/p4_16_samples_outputs/issue1638-midend.p4

@@ -32,17 +32,17 @@ control MyC(inout hdr_t hdr, inout meta_t meta, in intrinsic_metadata_t intr_md)
         }
         default_action = NoAction_1();
     }
-    @hidden action issue1638l23() {
+    @hidden action issue1638l20() {
         key_0 = 8w0;
     }
-    @hidden table tbl_issue1638l23 {
+    @hidden table tbl_issue1638l20 {
         actions = {
-            issue1638l23();
+            issue1638l20();
         }
-        const default_action = issue1638l23();
+        const default_action = issue1638l20();
     }
     apply {
-        tbl_issue1638l23.apply();
+        tbl_issue1638l20.apply();
         c2_a.apply();
     }
 }

testdata/p4_16_samples_outputs/issue1937-2-bmv2-frontend.p4

@@ -28,7 +28,7 @@ parser parserImpl(packet_in packet, out headers_t hdr, inout metadata_t meta, in
         transition foo_start_0;
     }
     state foo_start_0 {
-        hdr.h1.f2 = 8w5 >> 2;
+        hdr.h1.f2 = 8w1;
         transition start_1;
     }
     state start_1 {

testdata/p4_16_samples_outputs/issue1937-3-bmv2-frontend.p4

@@ -19,7 +19,7 @@ control ingressImpl(inout headers_t hdr, inout metadata_t meta, inout standard_m
     apply {
         tmp = hdr.h1.f1;
         hdr.h1.f1 = tmp >> 2;
-        hdr.h1.f2 = 8w5 >> 2;
+        hdr.h1.f2 = 8w1;
     }
 }
 

testdata/p4_16_samples_outputs/issue1937-frontend.p4

@@ -19,7 +19,7 @@ parser parserImpl(out h1_t hdr) {
         transition foo_start_0;
     }
     state foo_start_0 {
-        hdr.f2 = 8w5 >> 2;
+        hdr.f2 = 8w1;
         transition start_1;
     }
     state start_1 {

testdata/p4_16_samples_outputs/issue2303-frontend.p4

@@ -33,7 +33,7 @@ parser p(packet_in pkt, out Headers hdr, inout Meta m, inout standard_metadata_t
 
 control ingress(inout Headers h, inout Meta m, inout standard_metadata_t sm) {
     apply {
-        h.h.a = ((Meta){f0 = 8w0,f1 = 8w0,f2 = 8w0}).f0;
+        h.h.a = 8w0;
     }
 }
 

testdata/p4_16_samples_outputs/issue2648-frontend.p4

@@ -26,7 +26,7 @@ control ingress(inout Headers h) {
     @name("ingress.tmp_0") bit<8> tmp_0;
     @name("ingress.retval") bit<8> retval;
     apply {
-        retval = ((H){a = 8w1}).a;
+        retval = 8w1;
         tmp = retval;
         tmp_0 = tmp;
         h.h[tmp_0].a = 8w1;

testdata/p4_16_samples_outputs/issue4500-frontend.p4

@@ -7,9 +7,7 @@ extern void baz();
 control c() {
     apply {
         bar(E.e0);
-        if (E.e0 == E.e0) {
-            baz();
-        }
+        baz();
     }
 }
 

testdata/p4_16_samples_outputs/issue4548-first.p4

@@ -0,0 +1,19 @@
+#include <core.p4>
+
+bit<16> fun1(bit<8> args1) {
+    return (bit<16>)args1;
+}
+bit<8> fun2(bit<4> args2) {
+    fun1(8w10);
+    return 8w0;
+}
+control ingress() {
+    apply {
+        fun2(4w3);
+        fun2(4w3);
+    }
+}
+
+control Ingress();
+package top(Ingress ig);
+top(ingress()) main;

testdata/p4_16_samples_outputs/issue4548-frontend.p4

@@ -0,0 +1,10 @@
+#include <core.p4>
+
+control ingress() {
+    apply {
+    }
+}
+
+control Ingress();
+package top(Ingress ig);
+top(ingress()) main;

testdata/p4_16_samples_outputs/issue4548-midend.p4

@@ -0,0 +1,10 @@
+#include <core.p4>
+
+control ingress() {
+    apply {
+    }
+}
+
+control Ingress();
+package top(Ingress ig);
+top(ingress()) main;

testdata/p4_16_samples_outputs/issue4548.p4

@@ -0,0 +1,19 @@
+#include <core.p4>
+
+bit<16> fun1(bit<8> args1) {
+    return (bit<16>)args1;
+}
+bit<8> fun2(bit<4> args2) {
+    fun1(8w10);
+    return 8w0;
+}
+control ingress() {
+    apply {
+        fun2(4w3);
+        fun2(4w3);
+    }
+}
+
+control Ingress();
+package top(Ingress ig);
+top(ingress()) main;

testdata/p4_16_samples_outputs/named-arg1-frontend.p4

@@ -6,7 +6,7 @@ parser par(out bool b) {
         transition adder_0_start;
     }
     state adder_0_start {
-        x_0 = 32w0 + 32w6;
+        x_0 = 32w6;
         transition start_0;
     }
     state start_0 {