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* switch code fragments in comments to drop { } because the linter is
  over aggressive
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@alan-baker
alan-baker committed Sep 1, 2023
1 parent 6a80aaa commit b8f7b88
Showing 1 changed file with 51 additions and 80 deletions.
131 changes: 51 additions & 80 deletions src/webgpu/shader/execution/reconvergence/util.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -995,11 +995,10 @@ export class Program {
}

/**
* switch (subgroup_invocation_id & 3) {
* default { }
* case 0x3: { ... }
* case 0xc: { ... }
* }
* switch (subgroup_invocation_id & 3)
* default
* case 0x3: ...
* case 0xc: ...
*
* This is not generated for maximal style cases because it is not clear what
* convergence should be expected. There are multiple valid lowerings of a
Expand Down Expand Up @@ -2279,18 +2278,15 @@ ${this.functions[i]}`;
* Equivalent to:
*
* ballot(); // fully uniform
* if (inputs[1] == 1) {
* if (inputs[1] == 1)
* ballot(); // fullly uniform
* for (var i = 0; i < 3; i++) {
* for (var i = 0; i < 3; i++)
* ballot(); // Simulation expects fully uniform, WGSL does not.
* if (testBit(vec4u(0xaaaaaaaa,0xaaaaaaa,0xaaaaaaaa,0xaaaaaaaa), subgroup_id)) {
* if (testBit(vec4u(0xaaaaaaaa,0xaaaaaaa,0xaaaaaaaa,0xaaaaaaaa), subgroup_id))
* ballot(); // non-uniform
* continue;
* }
* ballot(); // non-uniform
* }
* ballot(); // fully uniform
* }
* ballot(); // fully uniform
*
* @param beginLoop The loop type
Expand Down Expand Up @@ -2344,18 +2340,16 @@ ${this.functions[i]}`;
* Equivalent to:
*
* ballot(); // uniform
* if (subgroup_id < 16) {
* if (subgroup_id < 16)
* ballot(); // 0xffff
* if (testbit(vec4u(0x00ff00ff,00ff00ff,00ff00ff,00ff00ff), subgroup_id)) {
* if (testbit(vec4u(0x00ff00ff,00ff00ff,00ff00ff,00ff00ff), subgroup_id))
* ballot(); // 0xff
* if (inputs[1] == 1) {
* if (inputs[1] == 1)
* ballot(); // 0xff
* }
* ballot(); // 0xff
* } else {
* else
* ballot(); // 0xF..0000
* return;
* }
* ballot; // 0xffff
*
* In this program, subgroups larger than 16 invocations diverge at the first if.
Expand Down Expand Up @@ -2407,19 +2401,16 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* if subgroup_id < inputs[107] {
* if subgroup_id < inputs[112] {
* if subgroup_id < inputs[107]
* if subgroup_id < inputs[112]
* ballot();
* if testBit(vec4u(0xd2f269c6,0xffe83b3f,0xa279f695,0x58899224), subgroup_id) {
* if testBit(vec4u(0xd2f269c6,0xffe83b3f,0xa279f695,0x58899224), subgroup_id)
* ballot();
* } else {
* else
* ballot()
* }
* ballot();
* } else {
* else
* ballot();
* }
* }
*
* The first two if statements are uniform for subgroup sizes 64 or less.
* The third if statement is non-uniform for all subgroup sizes.
Expand Down Expand Up @@ -2463,13 +2454,11 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* for (var i = 0; ; i++, ballot()) {
* for (var i = 0; ; i++, ballot())
* ballot();
* if (subgroupElect()) {
* if (subgroupElect())
* ballot();
* break;
* }
* }
* ballot();
*
* @param beginType The loop type
Expand Down Expand Up @@ -2501,13 +2490,11 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* for (var i = 0; i < subgroup_invocation_id + 1; i++) {
* for (var i = 0; i < subgroup_invocation_id + 1; i++)
* ballot();
* }
* ballot();
* for (var i = 0; i < subgroup_invocation_id + 1; i++) {
* for (var i = 0; i < subgroup_invocation_id + 1; i++)
* ballot();
* }
* ballot();
*/
public predefinedProgramForVar() {
Expand All @@ -2533,32 +2520,25 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* fn f0() {
* for (var i = 0; i < inputs[3]; i++) {
* fn f0()
* for (var i = 0; i < inputs[3]; i++)
* f1(i);
* ballot();
* }
* ballot();
* if (inputs[3] == 3) {
* if (inputs[3] == 3)
* f2();
* ballot();
* }
* ballot()
* }
* fn f1(i : u32) {
* fn f1(i : u32)
* ballot();
* if (subgroup_invocation_id == i) {
* if (subgroup_invocation_id == i)
* ballot();
* return;
* }
* }
* fn f2() {
* fn f2()
* ballot();
* if (testBit(vec4u(0xaaaaaaaa,0xaaaaaaaa,0xaaaaaaaa,0xaaaaaaaa), local_invocation_index)) {
* if (testBit(vec4u(0xaaaaaaaa,0xaaaaaaaa,0xaaaaaaaa,0xaaaaaaaa), local_invocation_index))
* ballot();
* return;
* }
* }
*/
public predefinedProgramCall() {
this.masks[4 + 0] = 0xaaaaaaaa;
Expand Down Expand Up @@ -2609,12 +2589,11 @@ ${this.functions[i]}`;
* Equivalent to:
*
* ballot()
* switch (inputs[5]) {
* default { }
* case 6 { ballot(); }
* case 5 { ballot(); }
* case 7 { ballot(); }
* }
* switch (inputs[5])
* default
* case 6 ballot();
* case 5 ballot();
* case 7 ballot();
* ballot();
*
*/
Expand Down Expand Up @@ -2644,13 +2623,12 @@ ${this.functions[i]}`;
* Equivalent to:
*
* ballot();
* switch subgroup_invocation_id & 3 {
* default { }
* case 0: { ballot(); }
* case 1: { ballot(); }
* case 2: { ballot(); }
* case 3: { ballot(); }
* }
* switch subgroup_invocation_id & 3
* default
* case 0: ballot();
* case 1: ballot();
* case 2: ballot();
* case 3: ballot();
* ballot();
*/
public predefinedProgramSwitchVar() {
Expand Down Expand Up @@ -2681,19 +2659,15 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* for (var i0 = 0u; i0 < inputs[3]; i0++) {
* for (var i1 = 0u; i1 < inputs[3]; i1++) {
* for (var i2 = 0u; i2 < subgroup_invocation_id + 1; i2++) {
* for (var i0 = 0u; i0 < inputs[3]; i0++)
* for (var i1 = 0u; i1 < inputs[3]; i1++)
* for (var i2 = 0u; i2 < subgroup_invocation_id + 1; i2++)
* ballot();
* switch i_loop {
* case 1 { ballot(); }
* case 2 { ballot(); }
* default { ballot(); }
* }
* switch i_loop
* case 1 ballot();
* case 2 ballot();
* default ballot();
* ballot();
* }
* }
* }
*/
public predefinedProgramSwitchLoopCount(loop: number) {
this.ops.push(new Op(OpType.ForUniform, 1));
Expand Down Expand Up @@ -2731,11 +2705,10 @@ ${this.functions[i]}`;
/**
* Equivalent to:
*
* switch subgroup_invocation_id & 0x3 {
* default { }
* case 0,1 { ballot(); }
* case 2,3 { ballot(); }
* }
* switch subgroup_invocation_id & 0x3
* default
* case 0,1 ballot();
* case 2,3 ballot();
*/
public predefinedProgramSwitchMulticase() {
this.ops.push(new Op(OpType.Store, this.storeBase + this.ops.length));
Expand All @@ -2761,12 +2734,10 @@ ${this.functions[i]}`;
* Equivalent to:
*
* ballot();
* for (var i = 0; i < inputs[3]; i++) {
* for (var i = 0; i < inputs[3]; i++)
* ballot();
* if (subgroupElect()) {
* if (subgroupElect())
* continue;
* }
* }
* ballot();
*
* This case can distinguish between Workgroup and WGSLv1 reconvergence.
Expand Down

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