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Value block reassignment uses StoreLocal

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As part of removing Instruction.lvalue we need to ensure that it is only used to 
represent that instruction's value — the InstructionKind should always be Const. 
The one place where we violated this was for value blocks, specifically 
ConditionalExpression and LogicalExpression. For both of those, we generate a 
single temporary place to represent the expression result. Then the consequent 
and alternate branch ended in a `LoadLocal` that reassigned that temporary (in 
the lvalue) to the result of that branch. 

This PR changes to use StoreLocal instead, and updates the recently added 
validation pass to ensure that all identifiers that appear in an 
Instruction.lvalue are only ever assigned once.
This commit is contained in:
Joe Savona
2023-03-03 17:09:26 -08:00
parent ca9d49090a
commit fe2d179a61
4 changed files with 106 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
compiler/forget/src/CompilerPipeline.ts
+2
View File
@@ -58,6 +58,8 @@ export function* run(
mergeConsecutiveBlocks(hir);
yield log({ kind: "hir", name: "MergeConsecutiveBlocks", value: hir });
validateConsistentIdentifiers(hir);
enterSSA(hir);
yield log({ kind: "hir", name: "SSA", value: hir });
compiler/forget/src/HIR/BuildHIR.ts
+34 -9
View File
@@ -1041,10 +1041,19 @@ function lowerExpression(
// Block for the consequent (if the test is truthy)
const consequentBlock = builder.enter("value", (_blockId) => {
const consequent = lowerExpressionToTemporary(
builder,
expr.get("consequent")
);
builder.push({
id: makeInstructionId(0),
lvalue: { ...place },
value: lowerExpression(builder, expr.get("consequent")),
lvalue: buildTemporaryPlace(builder, exprLoc),
value: {
kind: "StoreLocal",
lvalue: { kind: InstructionKind.Const, place: { ...place } },
value: consequent,
loc: exprLoc,
},
loc: exprLoc,
});
return {
@@ -1056,10 +1065,19 @@ function lowerExpression(
});
// Block for the alternate (if the test is not truthy)
const alternateBlock = builder.enter("value", (_blockId) => {
const alternate = lowerExpressionToTemporary(
builder,
expr.get("alternate")
);
builder.push({
id: makeInstructionId(0),
lvalue: { ...place },
value: lowerExpression(builder, expr.get("alternate")),
lvalue: buildTemporaryPlace(builder, exprLoc),
value: {
kind: "StoreLocal",
lvalue: { kind: InstructionKind.Const, place: { ...place } },
value: alternate,
loc: exprLoc,
},
loc: exprLoc,
});
return {
@@ -1106,10 +1124,11 @@ function lowerExpression(
const consequent = builder.enter("value", () => {
builder.push({
id: makeInstructionId(0),
lvalue: { ...place },
lvalue: buildTemporaryPlace(builder, leftPlace.loc),
value: {
kind: "LoadLocal",
place: { ...leftPlace },
kind: "StoreLocal",
lvalue: { kind: InstructionKind.Const, place: { ...place } },
value: { ...leftPlace },
loc: leftPlace.loc,
},
loc: exprLoc,
@@ -1122,10 +1141,16 @@ function lowerExpression(
};
});
const alternate = builder.enter("value", () => {
const right = lowerExpressionToTemporary(builder, expr.get("right"));
builder.push({
id: makeInstructionId(0),
lvalue: { ...place },
value: lowerExpression(builder, expr.get("right")),
lvalue: buildTemporaryPlace(builder, right.loc),
value: {
kind: "StoreLocal",
lvalue: { kind: InstructionKind.Const, place: { ...place } },
value: { ...right },
loc: right.loc,
},
loc: exprLoc,
});
return {
compiler/forget/src/HIR/ValidateConsistentIdentifiers.ts
+11
View File
@@ -13,6 +13,7 @@ import {
IdentifierId,
SourceLocation,
} from "./HIR";
import { printPlace } from "./PrintHIR";
import { eachInstructionValueOperand, eachTerminalOperand } from "./visitors";
/**
@@ -21,6 +22,7 @@ import { eachInstructionValueOperand, eachTerminalOperand } from "./visitors";
*/
export function validateConsistentIdentifiers(fn: HIRFunction): void {
const identifiers: Identifiers = new Map();
const assignments: Set<IdentifierId> = new Set();
for (const [, block] of fn.body.blocks) {
for (const phi of block.phis) {
validate(identifiers, phi.id);
@@ -35,6 +37,15 @@ export function validateConsistentIdentifiers(fn: HIRFunction): void {
instr.lvalue.loc
);
}
if (assignments.has(instr.lvalue.identifier.id)) {
CompilerError.invariant(
`Expected lvalues to be assigned exactly once, found duplicate assignment of '${printPlace(
instr.lvalue
)}'`,
instr.lvalue.loc
);
}
assignments.add(instr.lvalue.identifier.id);
validate(identifiers, instr.lvalue.identifier, instr.lvalue.loc);
for (const operand of eachInstructionValueOperand(instr.value)) {
validate(identifiers, operand.identifier, operand.loc);
compiler/forget/src/ReactiveScopes/BuildReactiveFunction.ts
+59 -10
View File
@@ -519,16 +519,9 @@ class Driver {
loc: SourceLocation
): { block: BlockId; value: ReactiveValue; place: Place; id: InstructionId } {
const defaultBlock = this.cx.ir.blocks.get(id)!;
if (
defaultBlock.terminal.kind === "goto" ||
defaultBlock.terminal.kind === "branch"
) {
if (defaultBlock.terminal.kind === "branch") {
const instructions = defaultBlock.instructions;
if (instructions.length === 0) {
invariant(
defaultBlock.terminal.kind === "branch",
"Expected instructions for non-branch terminal"
);
return {
block: defaultBlock.id,
place: defaultBlock.terminal.test,
@@ -541,6 +534,11 @@ class Driver {
};
} else if (defaultBlock.instructions.length === 1) {
const instr = defaultBlock.instructions[0]!;
invariant(
instr.lvalue.identifier.id ===
defaultBlock.terminal.test.identifier.id,
"Expected branch block to end in an instruction that sets the test value"
);
return {
block: defaultBlock.id,
place: instr.lvalue!,
@@ -558,7 +556,58 @@ class Driver {
};
return {
block: defaultBlock.id,
place: instr.lvalue!,
place: defaultBlock.terminal.test,
value: sequence,
id: defaultBlock.terminal.id,
};
}
} else if (defaultBlock.terminal.kind === "goto") {
const instructions = defaultBlock.instructions;
if (instructions.length === 0) {
invariant(
false,
"Expected goto value block to have at least one instruction"
);
} else if (defaultBlock.instructions.length === 1) {
const instr = defaultBlock.instructions[0]!;
let place: Place = instr.lvalue!;
let value: ReactiveValue = instr.value;
if (instr.value.kind === "StoreLocal") {
place = instr.value.lvalue.place;
value = {
kind: "LoadLocal",
place: instr.value.value,
loc: instr.value.value.loc,
};
}
return {
block: defaultBlock.id,
place,
value,
id: instr.id,
};
} else {
const instr = defaultBlock.instructions.at(-1)!;
let place: Place = instr.lvalue!;
let value: ReactiveValue = instr.value;
if (instr.value.kind === "StoreLocal") {
place = instr.value.lvalue.place;
value = {
kind: "LoadLocal",
place: instr.value.value,
loc: instr.value.value.loc,
};
}
const sequence: ReactiveSequenceValue = {
kind: "SequenceExpression",
instructions: defaultBlock.instructions.slice(0, -1),
id: instr.id,
value,
loc: loc,
};
return {
block: defaultBlock.id,
place,
value: sequence,
id: instr.id,
};
@@ -675,7 +724,7 @@ class Driver {
};
invariant(
consequent.place.identifier === alternate.place.identifier,
"Expected the consquent and alternate of a ternary to store a value to the same place"
"Expected the consequent and alternate of a ternary to store a value to the same place"
);
return {
place: { ...consequent.place },