CFG: Have the basic if/then case managed

Author: jecisc

src/FAST-Python-Tools-Tests/FASTPythonCFGTest.class.st

@@ -34,24 +34,28 @@ FASTPythonCFGTest >> setUp [
 { #category : 'tests' }
 FASTPythonCFGTest >> testFunctionWithIf [
 
-	| nextBlock |
-	self skip.
-	self flag: #todo. "Finish"
+	| thenBlock nullBlock |
 	self buildCFGFor: 'def f(i):
     if i > 3:
         print(i)'.
 
 	self assert: startBlock isConditional.
-	self assert: startBlock isFinal. "If the condition is false then the block is indeed final"
+	self deny: startBlock isExit.
 	self assert: startBlock statements size equals: 1.
-	self assert: (startBlock statements first class isOfType: FASTPyComparisonOperator).
+	self assert: (startBlock firstStatement class isOfType: FASTPyComparisonOperator).
 	self assert: startBlock nextBlocks size equals: 2.
-	self assert: (startBlock nextBlock select: #isNullBlock) size equals: 1.
-
-	nextBlock := startBlock nextBlockForValue: true.
-	self assert: nextBlock isConditional not.
-	self assert: nextBlock isFinal.
-	self assertEmpty: nextBlock statements
+	self assert: (startBlock nextBlocks select: #isNullBlock) size equals: 1.
+
+	thenBlock := startBlock nextTrueBlock.
+	self assert: thenBlock isConditional not.
+	self deny: thenBlock isExit.
+	self assert: thenBlock statements size equals: 1.
+	self assert: (thenBlock firstStatement isOfType: FASTPyCall).
+
+	nullBlock := startBlock nextFalseBlock.
+	self assert: nullBlock isNullBlock.
+	self assert: nullBlock identicalTo: thenBlock nextBlock.
+	self assert: nullBlock isExit
 ]
 
 { #category : 'tests' }
@@ -61,8 +65,9 @@ FASTPythonCFGTest >> testFunctionWithOneStatement [
 	print("Hello")'.
 
 	self assert: startBlock isStart.
-	self assert: startBlock nextBlock isNullBlock.
-	self assert: startBlock statements size equals: 1
+	self assert: startBlock isFinal.
+	self assert: startBlock statements size equals: 1.
+	self assertEmpty: startBlock nextBlocks
 ]
 
 { #category : 'tests' }
@@ -75,8 +80,9 @@ FASTPythonCFGTest >> testFunctionWithSimpleReturn [
 	return i'.
 
 	self assert: startBlock isStart.
-	self assert: startBlock nextBlock isNullBlock.
-	self assert: startBlock statements size equals: 4
+	self assert: startBlock isFinal.
+	self assert: startBlock statements size equals: 4.
+	self assertEmpty: startBlock nextBlocks
 ]
 
 { #category : 'tests' }
@@ -88,6 +94,7 @@ FASTPythonCFGTest >> testFunctionWithSimpleStatements [
 	print(i)'.
 
 	self assert: startBlock isStart.
-	self assert: startBlock nextBlock isNullBlock.
-	self assert: startBlock statements size equals: 3
+	self assert: startBlock isFinal.
+	self assert: startBlock statements size equals: 3.
+	self assertEmpty: startBlock nextBlocks
 ]

src/FAST-Python-Tools/FASTAbstractBasicBlock.extension.st

@@ -15,6 +15,13 @@ FASTAbstractBasicBlock >> inspectionVisualizationContext: aContext [
 	aContext active: self isStart
 ]
 
+{ #category : '*FAST-Python-Tools' }
+FASTAbstractBasicBlock >> isExit [
+
+	self flag: #todo. "I implemented this because #isFinal is currently not right. This should be removed once we fix the FAST CFG model."
+	^ self nextBlocks isEmpty
+]
+
 { #category : '*FAST-Python-Tools' }
 FASTAbstractBasicBlock >> withAllFollowingBlocks [
 

src/FAST-Python-Tools/FASTCFGVisualizationBuilder.class.st

@@ -33,15 +33,10 @@ FASTCFGVisualizationBuilder >> basicBlockShape: aBasicBlock [
 
 	| shape |
 	shape := aBasicBlock isStart
-		         ifTrue: [
-				         aBasicBlock isFinal
-					         ifTrue: [ self startAndFinalBlockShape ]
-					         ifFalse: [ self startBlockShape ] ]
-		         ifFalse: [
-				         aBasicBlock isFinal
-					         ifTrue: [ self finalBlockShape ]
-					         ifFalse: [ self normalBlockShape ] ].
+		         ifTrue: [ aBasicBlock nextBlocks ifEmpty: [ self startAndFinalBlockShape ] ifNotEmpty: [ self startBlockShape ] ]
+		         ifFalse: [ aBasicBlock nextBlocks ifEmpty: [ self finalBlockShape ] ifNotEmpty: [ self normalBlockShape ] ].
 	aBasicBlock isConditional ifTrue: [ shape color: self conditionalBlockColor ].
+	aBasicBlock isNullBlock ifTrue: [ shape color: self nullBlockColor ].
 	^ shape
 ]
 
@@ -58,6 +53,7 @@ FASTCFGVisualizationBuilder >> buildLegend [
 	legend text: 'start & final block' withShape: self startAndFinalBlockShape.
 	legend text: 'Normal block' withShape: self normalBlockShape.
 	legend text: 'Conditional block' withShape: (self normalBlockShape color: self conditionalBlockColor).
+	legend text: 'Null block' withShape: (self normalBlockShape color: self nullBlockColor).
 	legend build
 ]
 
@@ -110,6 +106,12 @@ FASTCFGVisualizationBuilder >> normalBlockShape [
 		  yourself
 ]
 
+{ #category : 'hooks' }
+FASTCFGVisualizationBuilder >> nullBlockColor [
+
+	^ Color green
+]
+
 { #category : 'instance creation' }
 FASTCFGVisualizationBuilder >> openOn: aCFGNode [
 

src/FAST-Python-Tools/FASTConditionalBasicBlock.extension.st

@@ -0,0 +1,15 @@
+Extension { #name : 'FASTConditionalBasicBlock' }
+
+{ #category : '*FAST-Python-Tools' }
+FASTConditionalBasicBlock >> nextFalseBlock [
+
+	self flag: #todo. "This should move to FAST."
+	^ self nextBlockForValue: false
+]
+
+{ #category : '*FAST-Python-Tools' }
+FASTConditionalBasicBlock >> nextTrueBlock [
+
+	self flag: #todo. "This should move to FAST."
+	^ self nextBlockForValue: true
+]

src/FAST-Python-Tools/FASTPythonCFGBuilder.class.st

@@ -1,5 +1,7 @@
 "
 I am a class taking a FAST Python entity and returning a Control Flow Graph.
+
+If we have multiple end blocks in a method, we create a virtual `FASTNullBlock` to have only one end point. In the case of Python, this node represents a **`return None`** that is the implicite return of functions in Python.
 "
 Class {
 	#name : 'FASTPythonCFGBuilder',

src/FAST-Python-Tools/FASTPythonCFGVisitor.class.st

@@ -18,29 +18,44 @@ FASTPythonCFGVisitor >> visitFASTPyExpression: aFASTPyExpression [
 { #category : 'visiting' }
 FASTPythonCFGVisitor >> visitFASTPyFunctionDefinition: aFunction [
 	"We do not manage the function in itself only its content"
+
 	(aFunction containedEntities sorted: #endPos ascending) do: [ :child | child accept: self ].
 
 	cfgBuilder basicBlocks first isStart: true.
 
-	"case where method has no return instruction (void signature)"
-	cfgBuilder currentBlock ifNotNil: [ cfgBuilder chainPendingBlocksTo: FASTNullBlock new ]
+	"If an if ends without having an else part and without having further statements, we add a null block."
+	cfgBuilder basicBlocks
+		detect: [ :block | block isConditional and: [ block nextFalseBlock isNil ] ]
+		ifFound: [ cfgBuilder newBasicBlock: FASTNullBlock ]
 ]
 
 { #category : 'visiting' }
-FASTPythonCFGVisitor >> visitFASTPyReturnStatement: aReturn [
+FASTPythonCFGVisitor >> visitFASTPyIfStatement: anIfStatement [
+	"We do not want to apply the visit statement in the case of the if"
+
+	| conditionalBlock |
+	self visitFASTTConditionalStatement: anIfStatement.
+	conditionalBlock := cfgBuilder currentBlock.
+
+	self visitEntity: anIfStatement thenClause.
 
-	super visitFASTPyReturnStatement: aReturn.
+	"adding a new pending action, either for the new else block or following code if no elsePart"
+	cfgBuilder addPendingNextBlockAction: [ :elseOrNextBlock | conditionalBlock nextBlock: elseOrNextBlock onValue: false ].
 
-	"We know that a return mark the end of a graph branch"
-	cfgBuilder currentBlock nextBlock: FASTNullBlock new
+	self visitCollection: anIfStatement elifClauses.
+
+	self visitFASTPyTWithElseClause: anIfStatement
 ]
 
 { #category : 'visiting' }
-FASTPythonCFGVisitor >> visitFASTTConditionalStatement: aStatement [
+FASTPythonCFGVisitor >> visitFASTPyThenClause: aThenClause [
 
-	cfgBuilder newConditionalBlock: aStatement.
+	| conditionalBlock |
+	conditionalBlock := cfgBuilder currentBlock.
+	cfgBuilder addPendingNextBlockAction: [ :thenBlock | conditionalBlock nextBlock: thenBlock onValue: true ].
+	cfgBuilder closeCurrentBlock.
 
-	super visitFASTTConditionalStatement: aStatement
+	super visitFASTPyThenClause: aThenClause
 ]
 
 { #category : 'visiting' }
@@ -66,3 +81,11 @@ FASTPythonCFGVisitor >> visitFASTTStatementBlock: aFASTTStatementBlock [
 
 	self visitCollection: aFASTTStatementBlock statements
 ]
+
+{ #category : 'visiting' }
+FASTPythonCFGVisitor >> visitFASTTWithCondition: aStatement [
+
+	cfgBuilder newConditionalBlock: aStatement condition.
+
+	super visitFASTTWithCondition: aStatement
+]