[blocks] Add basic blocks for CFG representation of the AST #64
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This patch adds a basic_block class and a function to translate the AST
to a CFG representation. It also dumps the basic block to std::cerr in
builder_context.cpp for debugging
The algorithm to convert the AST to CFG uses a worklist to do so, it
first creates basic blocks for all the top level AST elements, and then
using a worklist iteratively expands these top level AST elements,
adding more basic blocks between them.
bb1 ---> bb2 ==> bb1 ---> (bb-a1...bb-an) ---> bb2
It also pads if statement blocks with an exit blocks. This makes it
easier to handle loops, as we now have a single entry/exit into the if
block.
|----<then_block>----|
<if_block>----| |----<exit_block>
|----<else_block>----|
* buildit input source code
dyn_var<int> a = 0;
for (dyn_var<int> c = 0; c < 100; c = c + 3) {
for (dyn_var<int> b = 0; b < 10; b = b + 1) {
a = a + b;
}
}
* output of std::cerr, dump of the generated basic blocks
++++++ basic blocks ++++++
0:decl0: ; 0
br decl1,
1:decl1: ; decl0, 0
br label2,
2:label2: ; decl1, goto13, 0
br if3,
3:if3: ; label2, 0
LT_EXPR
VAR_EXPR
VAR (var1)
INT_CONST (100)
br stmt8, stmtexit7,
4:stmt8: ; if3, 0
br decl9,
5:decl9: ; stmt8, 1
br label10,
6:label10: ; decl9, goto21, 1
br if11,
7:if11: ; label10, 1
LT_EXPR
VAR_EXPR
VAR (var2)
INT_CONST (10)
br stmt18, stmtexit17,
8:stmt18: ; if11, 1
br expr19,
9:expr19: ; stmt18, 2
br expr20,
10:expr20: ; expr19, 2
br goto21,
11:goto21: ; expr20, 2
br label10,
12:stmtexit17: ; if11, 1
br expr12,
13:expr12: ; stmtexit17, 1
br goto13,
14:goto13: ; expr12, 1
br label2,
15:stmtexit7: ; if3, 0
br
++++++ basic blocks ++++++
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This patch also moves the debug statements to a separate function and calls them outside of builder_context.cpp. It also cleans up stray debug statements.
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This patch adds a basic_block class and a function to translate the AST to a CFG representation. It also dumps the basic block to std::cerr in builder_context.cpp for debugging
The algorithm to convert the AST to CFG uses a worklist to do so, it first creates basic blocks for all the top level AST elements, and then using a worklist iteratively expands these top level AST elements, adding more basic blocks between them.
bb1 ---> bb2 ==> bb1 ---> (bb-a1...bb-an) ---> bb2
It also pads if statement blocks with an exit blocks. This makes it easier to handle loops, as we now have a single entry/exit into the if block.
<if_block>----| |----<exit_block>
|----<else_block>----|
buildit input source code dyn_var a = 0;
for (dyn_var c = 0; c < 100; c = c + 3) {
for (dyn_var b = 0; b < 10; b = b + 1) {
a = a + b; } }
output of std::cerr, dump of the generated basic blocks ++++++ basic blocks ++++++
0:decl0: ; 0
br decl1, 1:decl1: ; decl0, 0
br label2, 2:label2: ; decl1, goto13, 0
br if3, 3:if3: ; label2, 0
LT_EXPR VAR_EXPR VAR (var1) INT_CONST (100) br stmt8, stmtexit7, 4:stmt8: ; if3, 0
br decl9, 5:decl9: ; stmt8, 1
br label10, 6:label10: ; decl9, goto21, 1
br if11, 7:if11: ; label10, 1
LT_EXPR VAR_EXPR VAR (var2) INT_CONST (10) br stmt18, stmtexit17, 8:stmt18: ; if11, 1
br expr19, 9:expr19: ; stmt18, 2
br expr20, 10:expr20: ; expr19, 2
br goto21, 11:goto21: ; expr20, 2
br label10, 12:stmtexit17: ; if11, 1
br expr12, 13:expr12: ; stmtexit17, 1
br goto13, 14:goto13: ; expr12, 1
br label2, 15:stmtexit7: ; if3, 0
br ++++++ basic blocks ++++++