chore(brillig_gen): Brillig artifact display for unit testing

compiler/noirc_evaluator/src/acir/tests/mod.rs

@@ -31,7 +31,7 @@ mod intrinsics;
 
 /// Test utility for converting [ACIR gen artifacts][crate::acir::ssa::Artifacts]
 /// into the final [ACIR Program][Program] in order to use its parser and human-readable text format.
-pub(crate) fn ssa_to_acir_program(src: &str) -> Program<FieldElement> {
+fn ssa_to_acir_program(src: &str) -> Program<FieldElement> {
     ssa_to_acir_program_with_debug_info(src).0
 }
 

compiler/noirc_evaluator/src/brillig/brillig_gen.rs

@@ -6,6 +6,7 @@ pub(crate) mod brillig_fn;
 pub(crate) mod brillig_globals;
 mod brillig_instructions;
 pub(crate) mod constant_allocation;
+#[cfg(test)]
 mod tests;
 mod variable_liveness;
 
@@ -91,3 +92,83 @@ pub(crate) fn gen_brillig_for(
     // Generate the final bytecode
     Ok(entry_point.finish())
 }
+
+#[cfg(test)]
+mod entry_point {
+    use crate::{
+        assert_artifact_snapshot,
+        brillig::{
+            BrilligOptions, brillig_gen::gen_brillig_for, brillig_ir::artifact::BrilligParameter,
+        },
+        ssa::ssa_gen::Ssa,
+    };
+
+    #[test]
+    fn entry_point_setup_basic() {
+        let src = " 
+        brillig(inline) fn main f0 {
+          b0(v0: u32, v1: u32):
+            v2 = add v0, v1
+            return v2
+        }
+        ";
+        let ssa = Ssa::from_str(src).unwrap();
+        let options = BrilligOptions::default();
+        let brillig = ssa.to_brillig(&options);
+
+        let args = vec![BrilligParameter::SingleAddr(32), BrilligParameter::SingleAddr(32)];
+        let entry = gen_brillig_for(ssa.main(), args, &brillig, &options).unwrap();
+
+        // foo is a very simple function returning the addition of its inputs, which is done at line 18.
+        // The rest of the code is some overhead added to every brillig function for handling inputs, outputs, globals, ...
+        //
+        // Here is a breakdown of the code:
+        // Line 1-9: The function starts with the handling of the inputs via the 'calldata copy'
+        // The inputs are put in registers 1 and 2
+        // Line 10: Calling the part that deals with brillig globals. In this simple example, there are no globals so
+        // it just returns immediately.
+        // Line 11: Calling the check_max_stack_depth_procedure (Lines 24-29), via the call 24. Returning from
+        // this procedure is going to line 18 (right after the call 24 on line 17)
+        // Line 18: the actual body of the function, which is a single add instruction.
+        // Line 19-21: An overflow check on the addition, which will trap if the addition overflowed.
+        // Line 22: Moving the result of the addition into the return register (register 1)
+        // Line 23: Returning from the function body, which goes back to line 12
+        // Line 12-15: Handling the return data, moving the return value into the right place in memory and stopping execution.
+        assert_artifact_snapshot!(entry, @r"
+        fn main
+         0: @2 = const u32 1
+         1: @1 = const u32 32839
+         2: @0 = const u32 71
+         3: sp[3] = const u32 2
+         4: sp[4] = const u32 0
+         5: @68 = calldata copy [sp[4]; sp[3]]
+         6: @68 = cast @68 to u32
+         7: @69 = cast @69 to u32
+         8: sp[1] = @68
+         9: sp[2] = @69
+        10: call 16
+        11: call 17
+        12: @70 = sp[1]
+        13: sp[2] = const u32 70
+        14: sp[3] = const u32 1
+        15: stop &[sp[2]; sp[3]]
+        16: return
+        17: call 24
+        18: sp[3] = u32 add sp[1], sp[2]
+        19: sp[4] = u32 lt_eq sp[1], sp[3]
+        20: jump if sp[4] to 22
+        21: call 30
+        22: sp[1] = sp[3]
+        23: return
+        24: @4 = const u32 30791
+        25: @3 = u32 lt @0, @4
+        26: jump if @3 to 29
+        27: @1 = indirect const u64 15764276373176857197
+        28: trap &[@1; @2]
+        29: return
+        30: @1 = indirect const u64 14990209321349310352
+        31: trap &[@1; @2]
+        32: return
+        ");
+    }
+}