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uniformity: test uniformity when a loop body only returns #4477

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320 changes: 282 additions & 38 deletions src/webgpu/shader/validation/uniformity/uniformity.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -185,60 +185,296 @@ function generateOp(op: string): string {
}
}

const kStatementKinds = ['if', 'for', 'while', 'switch', 'break-if'] as const;
const kStatementKinds = [
'if',
'for',
'while',
'switch',
'break-if',
'loop-always-break-op-inside',
'loop-always-return-op-inside',
'loop-always-break-op-continuing',
'loop-always-return-op-continuing',
'loop-always-break-op-after',
'loop-always-return-op-after',
'for-with-cond-always-break-op-inside',
'for-with-cond-always-return-op-inside',
'for-with-cond-always-break-op-after',
'for-with-cond-always-return-op-after',
'for-without-cond-always-break-op-inside',
'for-without-cond-always-return-op-inside',
'for-without-cond-always-break-op-after',
'for-without-cond-always-return-op-after',
'while-always-break-op-inside',
'while-always-return-op-inside',
'while-always-break-op-after',
'while-always-return-op-after',
] as const;
type kStatementType = (typeof kStatementKinds)[number];

type kSnippetInfo = {
// A WGSL code sippet that embeds a condition and operation-operation-under-test
// in a larger construct.
code: string;
// Is the operation-under-test sensitive to the uniformity of the condition?
sensitive: boolean;
};
function generateConditionalStatement(
statement: kStatementType,
condition: string,
op: string
): string {
const code = ``;
condition_name: string,
op_name: string
): kSnippetInfo {
const cond = generateCondition(condition_name);
const uniform_cond = generateCondition('uniform_storage_ro');
const op = generateOp(op_name);
switch (statement) {
case 'if': {
return `if ${generateCondition(condition)} {
${generateOp(op)};
}
`;
return {
sensitive: true,
code: `
if ${cond} {
${op};
}`,
};
}
case 'for': {
return `for (; ${generateCondition(condition)};) {
${generateOp(op)};
}
`;
return {
sensitive: true,
code: `
for (; ${cond}; ) {
${op};
}`,
};
}
case 'while': {
return `while ${generateCondition(condition)} {
${generateOp(op)};
}
`;
return {
sensitive: true,
code: `
while ${cond} {
${op};
}`,
};
}
case 'switch': {
return `switch u32(${generateCondition(condition)}) {
case 0: {
${generateOp(op)};
}
default: { }
}
`;
return {
sensitive: true,
code: `
switch u32(${cond}) {
case 0: {
${op};
}
default: { }
}`,
};
}
case 'break-if': {
// The initial 'if' prevents the loop from being infinite. Its condition
// is uniform, to ensure the first iteration of the the body executes
// uniformly. The uniformity of the second iteration depends entirely on
// the uniformity of the break-if condition.
return `loop {
if ${generateCondition('uniform_storage_ro')} { break; }
${generateOp(op)}
continuing {
break if ${generateCondition(condition)};
}
}
`;
return {
sensitive: true,
code: `
loop {
if ${uniform_cond} { break; }
${op}
continuing {
break if ${cond};
}
}`,
};
}
case 'loop-always-break-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
loop {
break;
if ${cond} { ${op} }
}`,
};
}
case 'loop-always-return-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
loop {
return;
if ${cond} { ${op} }
}`,
};
}
case 'loop-always-break-op-continuing': {
return {
sensitive: false, // The op is unreachable.
code: `
loop {
break;
continuing {
if ${cond} { ${op} }
}
}`,
};
}
case 'loop-always-return-op-continuing': {
return {
sensitive: false, // The op is unreachable.
code: `
loop {
return;
continuing {
if ${cond} { ${op} }
}
}`,
};
}
case 'loop-always-break-op-after': {
return {
sensitive: true,
code: `
loop {
break;
}
if ${cond} { ${op} }`,
};
}
case 'loop-always-return-op-after': {
return {
sensitive: false, // The op is unreachable.
code: `
loop {
return;
}
if ${cond} { ${op} }`,
};
}
case 'for-with-cond-always-break-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
for ( ;${uniform_cond}; ) {
break;
if ${cond} { ${op} }
}`,
};
}
case 'for-with-cond-always-return-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
for ( ;${uniform_cond}; ) {
return;
if ${cond} { ${op} }
}`,
};
}
case 'for-with-cond-always-break-op-after': {
return {
sensitive: true,
code: `
for ( ;${uniform_cond}; ) {
break;
}
if ${cond} { ${op} }`,
};
}
case 'for-with-cond-always-return-op-after': {
return {
// Desugars to a loop with a conditional break,
// before reaching the loop.
sensitive: true,
code: `
for ( ;${uniform_cond}; ) {
return;
}
if ${cond} { ${op} }`,
};
}
case 'for-without-cond-always-break-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
for ( ; ; ) {
break;
if ${cond} { ${op} }
}`,
};
}
case 'for-without-cond-always-return-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
for ( ; ; ) {
return;
if ${cond} { ${op} }
}`,
};
}
case 'for-without-cond-always-break-op-after': {
return {
sensitive: true,
code: `
for ( ; ; ) {
break;
}
if ${cond} { ${op} }`,
};
}
case 'for-without-cond-always-return-op-after': {
return {
// Desugars to a loop without a conditional break.
// So the op is unreachable.
sensitive: false,
code: `
for ( ; ; ) {
return;
}
if ${cond} { ${op} }`,
};
}
case 'while-always-break-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
while (${uniform_cond}) {
break;
if ${cond} { ${op} }
}`,
};
}
case 'while-always-return-op-inside': {
return {
sensitive: false, // The op is unreachable.
code: `
while (${uniform_cond}) {
return;
if ${cond} { ${op} }
}`,
};
}
case 'while-always-break-op-after': {
return {
sensitive: true,
code: `
while (${uniform_cond}) {
break;
}
if ${cond} { ${op} }`,
};
}
case 'while-always-return-op-after': {
return {
// Desugars to a loop with a conditional break,
// before reaching the loop.
sensitive: true,
code: `
while (${uniform_cond}) {
return;
}
if ${cond} { ${op} }`,
};
}
}

return code;
}

g.test('basics')
Expand Down Expand Up @@ -293,11 +529,15 @@ g.test('basics')
`;

// Simple control statement containing the op.
code += generateConditionalStatement(t.params.statement, t.params.cond, t.params.op);
const snippet = generateConditionalStatement(t.params.statement, t.params.cond, t.params.op);
code += snippet.code;

code += `\n}\n`;

t.expectCompileResult(t.params.expectation || t.params.op.startsWith('control_case'), code);
t.expectCompileResult(
t.params.expectation || t.params.op.startsWith('control_case') || !snippet.sensitive,
code
);
});

const kSubgroupOps = [
Expand Down Expand Up @@ -380,11 +620,15 @@ g.test('basics,subgroups')
`;

// Simple control statement containing the op.
code += generateConditionalStatement(t.params.statement, t.params.cond, t.params.op);
const snippet = generateConditionalStatement(t.params.statement, t.params.cond, t.params.op);
code += snippet.code;

code += `\n}\n`;

t.expectCompileResult(t.params.expectation || t.params.op.startsWith('control_case'), code);
t.expectCompileResult(
t.params.expectation || t.params.op.startsWith('control_case') || !snippet.sensitive,
code
);
});

const kFragmentBuiltinValues = [
Expand Down