Test system for testing IR

New system for testing generated IR based on pretty printing the IR and
comparing to a reference string. String comparison is an excellent
way to do IR comparisons because
* It's very simple to implement
* Writing test cases is simple
* It's easy to pinpoint errors in tests
* Irrelevant detail can easily be omitted in the pretty printing

The main downside is that, in principle, the pretty printing may have
ambiguities, and changing the pretty printing causes high churn in test
cases. However these seem like reasonable tradeoffs, given the benefits.

test/branching.jl

@@ -290,90 +290,7 @@ end
 #-------------------------------------------------------------------------------
 @testset "Detailed lowering tests" begin
 
-@test ir_as_text(test_mod, """
-begin
-    local a, b
-    if a
-        b
-    end
-end
-""") == """
-slot.₁/a
-(gotoifnot ssa.₁ label.₅)
-slot.₂/b
-(return ssa.₃)
-core.nothing
-(return ssa.₅)"""
-
-@test ir_as_text(test_mod, """
-begin
-    local a, b, c
-    if a
-        b
-    end
-    c
-end
-""") == """
-slot.₁/a
-(gotoifnot ssa.₁ label.₄)
-slot.₂/b
-slot.₃/c
-(return ssa.₄)"""
-
-@test ir_as_text(test_mod, """
-begin
-    local a, b, c
-    if a
-        b
-    else
-        c
-    end
-end
-""") == """
-slot.₁/a
-(gotoifnot ssa.₁ label.₅)
-slot.₂/b
-(return ssa.₃)
-slot.₃/c
-(return ssa.₅)"""
-
-@test ir_as_text(test_mod, """
-begin
-    local a, b, c, d
-    if a
-        b
-    else
-        c
-    end
-    d
-end
-""") == """
-slot.₁/a
-(gotoifnot ssa.₁ label.₅)
-slot.₂/b
-(goto label.₆)
-slot.₃/c
-slot.₄/d
-(return ssa.₆)"""
-
-# Blocks compile directly to branches
-@test ir_as_text(test_mod, """
-begin
-   local a, b, c, d
-   if (a; b && c)
-       d
-   end
-end
-""") == """
-slot.₁/a
-slot.₂/b
-(gotoifnot ssa.₂ label.₈)
-slot.₃/c
-(gotoifnot ssa.₄ label.₈)
-slot.₄/d
-(return ssa.₆)
-core.nothing
-(return ssa.₈)"""
+test_ir_cases(joinpath(@__DIR__,"branching_ir.jl"))
 
 end
 

test/branching_ir.jl

@@ -0,0 +1,88 @@
+######################################
+# Basic branching tail && value
+begin
+    local a, b
+    if a
+        b
+    end
+end
+#-------------------------
+1   slot.₁/a
+2   (gotoifnot ssa.₁ label.₅)
+3   slot.₂/b
+4   (return ssa.₃)
+5   core.nothing
+6   (return ssa.₅)
+
+######################################
+# Branching, !tail && !value
+begin
+    local a, b, c
+    if a
+        b
+    end
+    c
+end
+#-------------------------
+1   slot.₁/a
+2   (gotoifnot ssa.₁ label.₄)
+3   slot.₂/b
+4   slot.₃/c
+5   (return ssa.₄)
+
+######################################
+# Branching with else
+begin
+    local a, b, c
+    if a
+        b
+    else
+        c
+    end
+end
+#---------------------
+1   slot.₁/a
+2   (gotoifnot ssa.₁ label.₅)
+3   slot.₂/b
+4   (return ssa.₃)
+5   slot.₃/c
+6   (return ssa.₅)
+
+######################################
+# Branching with else, !tail && !value
+begin
+    local a, b, c, d
+    if a
+        b
+    else
+        c
+    end
+    d
+end
+#---------------------
+1   slot.₁/a
+2   (gotoifnot ssa.₁ label.₅)
+3   slot.₂/b
+4   (goto label.₆)
+5   slot.₃/c
+6   slot.₄/d
+7   (return ssa.₆)
+
+######################################
+# Blocks compile directly to branches
+begin
+   local a, b, c, d
+   if (a; b && c)
+       d
+   end
+end
+#---------------------
+1   slot.₁/a
+2   slot.₂/b
+3   (gotoifnot ssa.₂ label.₈)
+4   slot.₃/c
+5   (gotoifnot ssa.₄ label.₈)
+6   slot.₄/d
+7   (return ssa.₆)
+8   core.nothing
+9   (return ssa.₈)

test/loops.jl

@@ -53,6 +53,8 @@ break
 continue
 """)
 
+test_ir_cases(joinpath(@__DIR__, "loops_ir.jl"))
+
 # TODO: Test scope rules
 
 end

test/utils.jl

@@ -85,8 +85,37 @@ format_as_ast_macro(ex) = format_as_ast_macro(stdout, ex)
 
 #-------------------------------------------------------------------------------
 
-# Parse and lower `src`, and print statements from the linear IR in text format
-function ir_as_text(mod, src)
-    ex = JuliaLowering.lower(mod, parsestmt(SyntaxTree, src))
-    join(string.(children(ex[1])), "\n")
+# Test tools
+
+function match_ir_test_case(case_str)
+    m = match(r"# *([^\n]*)\n((?:.|\n)*)#----*\n((?:.|\n)*)"m, strip(case_str))
+    if isnothing(m)
+        error("Malformatted IR test case:\n$(repr(case_str))")
+    end
+    (name=strip(m[1]), input=strip(m[2]), output=strip(m[3]))
+end
+
+function format_ir_test_case(mod, input)
+    ex = parsestmt(SyntaxTree, input)
+    x = JuliaLowering.lower(mod, ex)
+    output = strip(sprint(JuliaLowering.print_ir, x))
+    output = replace(output, string(mod)=>"TestMod")
+end
+
+function test_ir_cases(filename)
+    str = read(filename, String)
+    cases = [match_ir_test_case(s) for s in split(str, r"####*") if strip(s) != ""]
+
+    mod = Module(:TestMod)
+    for (name,input,ref) in cases
+        output = format_ir_test_case(mod, input)
+        @testset "$name" begin
+            if output != ref
+                # Do our own error dumping, as @test will 
+                @error "Test \"$name\" failed" output=Text(output) ref=Text(ref)
+            end
+            @test output == ref
+        end
+    end
 end
+