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Add functions to find the matching ELSE, ENDIF expressions

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ExpressionId FindMatchingEndif(ExpressionId id)
   - Finds the closing ENDIF expression for a given IF expression.

ExpressionId FindMatchingElse(ExpressionId id)
   - Finds the ELSE expression for a given IF expression.
   - Returns -1, if this IF doesn't have an else

This patch is a preparation to the code analyzing required
for various optimization passes.

Change-Id: I893102a757c6a0bcacbcc1190c2b8ef08314eb97
This commit is contained in:
Darius Rueckert
2019-12-20 15:55:54 +01:00
parent 678c05b289
commit fdf9cfd320
3 changed files with 156 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/ceres/codegen/internal/expression_graph.h
+29
View File
@@ -74,6 +74,35 @@ class ExpressionGraph {
// can be used for further operations.
ExpressionId InsertBack(const Expression& expression);
// Finds the closing ENDIF expression for a given IF expression. Calling this
// method is only valid on IF expressions. If no suitable ENDIF is found,
// kInvalidExpressionId is returned. Example:
// <id> <expr> FindMatchingEndif(id)
// 0 IF 7
// 1 IF 3
// 2 ELSE -
// 3 ENDIF -
// 4 ELSE -
// 5 IF 6
// 6 ENDIF -
// 7 ENDIF -
ExpressionId FindMatchingEndif(ExpressionId id) const;
// Similar to FindMatchingEndif, but returns the matching ELSE expression. If
// no suitable ELSE is found, kInvalidExpressionId is returned.
// FindMatchingElse does not throw an error is this case, because IF without
// ELSE is allowed.
// <id> <expr> FindMatchingEndif(id)
// 0 IF 4
// 1 IF 2
// 2 ELSE -
// 3 ENDIF -
// 4 ELSE -
// 5 IF kInvalidEpressionId
// 6 ENDIF -
// 7 ENDIF -
ExpressionId FindMatchingElse(ExpressionId id) const;
private:
// All Expressions are referenced by an ExpressionId. The ExpressionId is
// the index into this array. Each expression has a list of ExpressionId as
internal/ceres/codegen/expression_graph_test.cc
+73 -1
View File
@@ -31,9 +31,9 @@
// This file tests the ExpressionGraph class. This test depends on the
// correctness of Expression.
//
#include "ceres/codegen/internal/expression.h"
#include "ceres/codegen/internal/expression_graph.h"
#include "ceres/codegen/internal/expression.h"
#include "gtest/gtest.h"
namespace ceres {
@@ -146,6 +146,78 @@ TEST(ExpressionGraph, DependsOn) {
ASSERT_TRUE(graph.DependsOn(3, 1));
}
TEST(ExpressionGraph, FindMatchingEndif) {
ExpressionGraph graph;
graph.InsertBack(Expression::CreateCompileTimeConstant(1));
graph.InsertBack(Expression::CreateCompileTimeConstant(2));
graph.InsertBack(Expression::CreateBinaryCompare("<", 0, 1));
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateElse());
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateElse());
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateIf(2)); // < if without matching endif
EXPECT_EQ(graph.Size(), 12);
// Code <id>
// v_0 = 1 0
// v_1 = 2 1
// v_2 = v_0 < v_1 2
// IF (v_2) 3
// IF (v_2) 4
// ELSE 5
// ENDIF 6
// ELSE 7
// IF (v_2) 8
// ENDIF 9
// ENDIF 10
// IF(v_2) 11
EXPECT_EQ(graph.FindMatchingEndif(3), 10);
EXPECT_EQ(graph.FindMatchingEndif(4), 6);
EXPECT_EQ(graph.FindMatchingEndif(8), 9);
EXPECT_EQ(graph.FindMatchingEndif(11), kInvalidExpressionId);
}
TEST(ExpressionGraph, FindMatchingElse) {
ExpressionGraph graph;
graph.InsertBack(Expression::CreateCompileTimeConstant(1));
graph.InsertBack(Expression::CreateCompileTimeConstant(2));
graph.InsertBack(Expression::CreateBinaryCompare("<", 0, 1));
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateElse());
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateElse());
graph.InsertBack(Expression::CreateIf(2));
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateEndIf());
graph.InsertBack(Expression::CreateIf(2)); // < if without matching endif
EXPECT_EQ(graph.Size(), 12);
// Code <id>
// v_0 = 1 0
// v_1 = 2 1
// v_2 = v_0 < v_1 2
// IF (v_2) 3
// IF (v_2) 4
// ELSE 5
// ENDIF 6
// ELSE 7
// IF (v_2) 8
// ENDIF 9
// ENDIF 10
// IF(v_2) 11
EXPECT_EQ(graph.FindMatchingElse(3), 7);
EXPECT_EQ(graph.FindMatchingElse(4), 5);
EXPECT_EQ(graph.FindMatchingElse(8), kInvalidExpressionId);
EXPECT_EQ(graph.FindMatchingEndif(11), kInvalidExpressionId);
}
TEST(ExpressionGraph, InsertExpression_UpdateReferences) {
// This test checks if references to shifted expressions are updated
// accordingly.
internal/ceres/expression_graph.cc
+54
View File
@@ -147,5 +147,59 @@ ExpressionId ExpressionGraph::InsertBack(const Expression& expression) {
return Size() - 1;
}
ExpressionId ExpressionGraph::FindMatchingEndif(ExpressionId id) const {
CHECK(ExpressionForId(id).type() == ExpressionType::IF)
<< "FindClosingControlExpression is only valid on IF "
"expressions.";
// Traverse downwards
for (ExpressionId i = id + 1; i < Size(); ++i) {
const auto& expr = ExpressionForId(i);
if (expr.type() == ExpressionType::ENDIF) {
return i;
} else if (expr.type() == ExpressionType::IF) {
// Found a nested IF.
// -> Jump over the block and continue behind it.
auto matching_endif = FindMatchingEndif(i);
if (matching_endif == kInvalidExpressionId) {
return kInvalidExpressionId;
}
i = matching_endif;
continue;
}
}
return kInvalidExpressionId;
}
ExpressionId ExpressionGraph::FindMatchingElse(ExpressionId id) const {
CHECK(ExpressionForId(id).type() == ExpressionType::IF)
<< "FindClosingControlExpression is only valid on IF "
"expressions.";
// Traverse downwards
for (ExpressionId i = id + 1; i < Size(); ++i) {
const auto& expr = ExpressionForId(i);
if (expr.type() == ExpressionType::ELSE) {
// Found it!
return i;
} else if (expr.type() == ExpressionType::ENDIF) {
// Found an endif even though we were looking for an ELSE.
// -> Return invalidId
return kInvalidExpressionId;
} else if (expr.type() == ExpressionType::IF) {
// Found a nested IF.
// -> Jump over the block and continue behind it.
auto matching_endif = FindMatchingEndif(i);
if (matching_endif == kInvalidExpressionId) {
return kInvalidExpressionId;
}
i = matching_endif;
continue;
}
}
return kInvalidExpressionId;
}
} // namespace internal
} // namespace ceres