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Commit 37e83379 by John Kessenich
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Merge pull request #22 from google/structured-do-while

Generate correctly structured do-while loops.
parents d2762564 c22f37cf
Showing with 285 additions and 210 deletions
SPIRV/GlslangToSpv.cpp
......@@ -1147,28 +1147,18 @@ bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIn
// body emission needs to know what the for-loop terminal is when it sees a "continue"
loopTerminal.push(node->getTerminal());
builder.makeNewLoop();
bool bodyOut = false;
if (! node->testFirst()) {
builder.endLoopHeaderWithoutTest();
if (node->getBody()) {
breakForLoop.push(true);
node->getBody()->traverse(this);
breakForLoop.pop();
}
bodyOut = true;
builder.createBranchToLoopTest();
}
builder.makeNewLoop(node->testFirst());
if (node->getTest()) {
node->getTest()->traverse(this);
// the AST only contained the test computation, not the branch, we have to add it
spv::Id condition = builder.accessChainLoad(TranslatePrecisionDecoration(node->getTest()->getType()));
builder.createLoopTestBranch(condition);
} else {
builder.createBranchToBody();
}
if (! bodyOut && node->getBody()) {
if (node->getBody()) {
breakForLoop.push(true);
node->getBody()->traverse(this);
breakForLoop.pop();
......
SPIRV/SpvBuilder.cpp
......@@ -1736,16 +1736,29 @@ void Builder::endSwitch(std::vector<Block*>& /*segmentBlock*/)
}
// Comments in header
void Builder::makeNewLoop()
void Builder::makeNewLoop(bool loopTestFirst)
{
Loop loop = { };
loop.function = &getBuildPoint()->getParent();
loop.header = new Block(getUniqueId(), *loop.function);
loop.merge = new Block(getUniqueId(), *loop.function);
loop.test = NULL;
loops.push({ });
Loop& loop = loops.top();
loops.push(loop);
loop.function = &getBuildPoint()->getParent();
loop.header = new Block(getUniqueId(), *loop.function);
loop.merge = new Block(getUniqueId(), *loop.function);
// Delaying creation of the loop body perturbs test results less,
// which makes for easier patch review.
// TODO(dneto): Create the loop body block here, instead of
// upon first use.
loop.body = 0;
loop.testFirst = loopTestFirst;
loop.isFirstIteration = 0;
// The loop test is always emitted before the loop body.
// But if the loop test executes at the bottom of the loop, then
// execute the test only on the second and subsequent iterations.
// Remember the block that branches to the loop header. This
// is required for the test-after-body case.
Block* preheader = getBuildPoint();
// Branch into the loop
createBranch(loop.header);
......@@ -1753,56 +1766,95 @@ void Builder::makeNewLoop()
// Set ourselves inside the loop
loop.function->addBlock(loop.header);
setBuildPoint(loop.header);
if (!loopTestFirst) {
// Generate code to defer the loop test until the second and
// subsequent iterations.
// A phi node determines whether we're on the first iteration.
loop.isFirstIteration = new Instruction(getUniqueId(), makeBoolType(), OpPhi);
// It's always the first iteration when coming from the preheader.
// All other branches to this loop header will need to indicate "false",
// but we don't yet know where they will come from.
loop.isFirstIteration->addIdOperand(makeBoolConstant(true));
loop.isFirstIteration->addIdOperand(preheader->getId());
getBuildPoint()->addInstruction(loop.isFirstIteration);
// Mark the end of the structured loop. This must exist in the loop header block.
createMerge(OpLoopMerge, loop.merge, LoopControlMaskNone);
// Generate code to see if this is the first iteration of the loop.
// It needs to be in its own block, since the loop merge and
// the selection merge instructions can't both be in the same
// (header) block.
Block* firstIterationCheck = new Block(getUniqueId(), *loop.function);
createBranch(firstIterationCheck);
loop.function->addBlock(firstIterationCheck);
setBuildPoint(firstIterationCheck);
loop.body = new Block(getUniqueId(), *loop.function);
// Control flow after this "if" normally reconverges at the loop body.
// However, the loop test has a "break branch" out of this selection
// construct because it can transfer control to the loop merge block.
createMerge(OpSelectionMerge, loop.body, SelectionControlMaskNone);
Block* loopTest = new Block(getUniqueId(), *loop.function);
createConditionalBranch(loop.isFirstIteration->getResultId(), loop.body, loopTest);
loop.function->addBlock(loopTest);
setBuildPoint(loopTest);
}
}
void Builder::createLoopTestBranch(Id condition)
{
Loop& loop = loops.top();
// If loop.test exists, then we've already generated the LoopMerge
// for this loop.
if (!loop.test)
createMerge(OpLoopMerge, loop.merge, LoopControlMaskNone);
// Branching to the "body" block will keep control inside
// the loop.
Block* body = new Block(getUniqueId(), *loop.function);
createConditionalBranch(condition, body, loop.merge);
loop.function->addBlock(body);
setBuildPoint(body);
// Generate the merge instruction. If the loop test executes before
// the body, then this is a loop merge. Otherwise the loop merge
// has already been generated and this is a conditional merge.
if (loop.testFirst) {
createMerge(OpLoopMerge, loop.merge, LoopControlMaskNone);
loop.body = new Block(getUniqueId(), *loop.function);
// Branching to the "body" block will keep control inside
// the loop.
createConditionalBranch(condition, loop.body, loop.merge);
loop.function->addBlock(loop.body);
setBuildPoint(loop.body);
} else {
// The branch to the loop merge block is the allowed exception
// to the structured control flow. Otherwise, control flow will
// continue to loop.body block. Since that is already the target
// of a merge instruction, and a block can't be the target of more
// than one merge instruction, we need to make an intermediate block.
Block* stayInLoopBlock = new Block(getUniqueId(), *loop.function);
createMerge(OpSelectionMerge, stayInLoopBlock, SelectionControlMaskNone);
// This is the loop test.
createConditionalBranch(condition, stayInLoopBlock, loop.merge);
// The dummy block just branches to the real loop body.
loop.function->addBlock(stayInLoopBlock);
setBuildPoint(stayInLoopBlock);
createBranchToBody();
}
}
void Builder::endLoopHeaderWithoutTest()
void Builder::createBranchToBody()
{
Loop& loop = loops.top();
assert(loop.body);
createMerge(OpLoopMerge, loop.merge, LoopControlMaskNone);
Block* body = new Block(getUniqueId(), *loop.function);
createBranch(body);
loop.function->addBlock(body);
setBuildPoint(body);
assert(!loop.test);
loop.test = new Block(getUniqueId(), *loop.function);
}
void Builder::createBranchToLoopTest()
{
Loop& loop = loops.top();
Block* testBlock = loop.test;
assert(testBlock);
createBranch(testBlock);
loop.function->addBlock(testBlock);
setBuildPoint(testBlock);
// This is a reconvergence of control flow, so no merge instruction
// is required.
createBranch(loop.body);
loop.function->addBlock(loop.body);
setBuildPoint(loop.body);
}
void Builder::createLoopContinue()
{
Loop& loop = loops.top();
if (loop.test)
createBranch(loop.test);
else
createBranch(loop.header);
createBranchToLoopHeaderFromInside(loops.top());
// Set up a block for dead code.
createAndSetNoPredecessorBlock("post-loop-continue");
}
......@@ -1821,7 +1873,7 @@ void Builder::closeLoop()
Loop& loop = loops.top();
// Branch back to the top
createBranch(loop.header);
createBranchToLoopHeaderFromInside(loop);
// Add the merge block and set the build point to it
loop.function->addBlock(loop.merge);
......@@ -1830,6 +1882,18 @@ void Builder::closeLoop()
loops.pop();
}
// Create a branch to the header of the given loop, from inside
// the loop body.
// Adjusts the phi node for the first-iteration value if needeed.
void Builder::createBranchToLoopHeaderFromInside(const Loop& loop)
{
createBranch(loop.header);
if (loop.isFirstIteration) {
loop.isFirstIteration->addIdOperand(makeBoolConstant(false));
loop.isFirstIteration->addIdOperand(getBuildPoint()->getId());
}
}
void Builder::clearAccessChain()
{
accessChain.base = 0;
......
SPIRV/SpvBuilder.h
......@@ -357,35 +357,25 @@ public:
// Finish off the innermost switch.
void endSwitch(std::vector<Block*>& segmentBB);
// Start the beginning of a new loop.
void makeNewLoop();
// Start the beginning of a new loop, and prepare the builder to
// generate code for the loop test.
// The loopTestFirst parameter is true when the loop test executes before
// the body. (It is false for do-while loops.)
void makeNewLoop(bool loopTestFirst);
// Add the branch for the loop test, based on the given condition.
// The true branch goes to the block that remains inside the loop, and
// the false branch goes to the loop's merge block. The builder insertion
// point will be placed at the start of the inside-the-loop block.
// The true branch goes to the first block in the loop body, and
// the false branch goes to the loop's merge block. The builder insertion
// point will be placed at the start of the body.
void createLoopTestBranch(Id condition);
// Finish generating the loop header block in the case where the loop test
// is at the bottom of the loop. It will include the LoopMerge instruction
// and a branch to the rest of the body. The loop header block must be
// separate from the rest of the body to make room for the the two kinds
// of *Merge instructions that might have to occur just before a branch:
// the loop header must have a LoopMerge as its second-last instruction,
// and the body might begin with a conditional branch, which must have its
// own SelectionMerge instruction.
// Also create the basic block that will contain the loop test, but don't
// insert it into the function yet. Any "continue" constructs in this loop
// will branch to the loop test block. The builder insertion point will be
// placed at the start of the body block.
void endLoopHeaderWithoutTest();
// Generate a branch to the loop test block. This can only be called if
// the loop test is at the bottom of the loop. The builder insertion point
// is left at the start of the test block.
void createBranchToLoopTest();
// Generate an unconditional branch to the loop body. The builder insertion
// point will be placed at the start of the body. Use this when there is
// no loop test.
void createBranchToBody();
// Add a branch to the test of the current (innermost) loop.
// The way we generate code, that's also the loop header.
void createLoopContinue();
// Add an exit (e.g. "break") for the innermost loop that you're in
......@@ -499,6 +489,9 @@ protected:
void createConditionalBranch(Id condition, Block* thenBlock, Block* elseBlock);
void dumpInstructions(std::vector<unsigned int>&, const std::vector<Instruction*>&) const;
struct Loop; // Defined below.
void createBranchToLoopHeaderFromInside(const Loop& loop);
SourceLanguage source;
int sourceVersion;
std::vector<const char*> extensions;
......@@ -543,11 +536,18 @@ protected:
// to the merge block when either the loop test fails, or when a
// nested "break" is encountered.
Block* merge;
// If not NULL, the test block is the basic block containing the loop
// test and the conditional branch back to the header or the merge
// block. This is created for "do-while" loops, and is the target of
// any "continue" constructs that might exist.
Block* test;
// The body block is the first basic block in the body of the loop, i.e.
// the code that is to be repeatedly executed, aside from loop control.
// This member is null until we generate code that references the loop
// body block.
Block* body;
// True when the loop test executes before the body.
bool testFirst;
// When the test executes after the body, this is defined as the phi
// instruction that tells us whether we are on the first iteration of
// the loop. Otherwise this is null.
Instruction* isFirstIteration;
// The function containing the loop.
Function* function;
};
......
Test/baseResults/spv.do-simple.vert.out
......@@ -5,7 +5,7 @@ Linked vertex stage:
// Module Version 99
// Generated by (magic number): 51a00bb
// Id's are bound by 26
// Id's are bound by 30
Source ESSL 300
1: ExtInstImport "GLSL.std.450"
......@@ -13,45 +13,52 @@ Linked vertex stage:
EntryPoint Vertex 4
Name 4 "main"
Name 9 "i"
Name 24 "gl_VertexID"
Name 25 "gl_InstanceID"
Name 28 "gl_VertexID"
Name 29 "gl_InstanceID"
Decorate 9(i) PrecisionHigh
Decorate 24(gl_VertexID) PrecisionHigh
Decorate 24(gl_VertexID) BuiltIn VertexId
Decorate 24(gl_VertexID) NoStaticUse
Decorate 25(gl_InstanceID) PrecisionHigh
Decorate 25(gl_InstanceID) BuiltIn InstanceId
Decorate 25(gl_InstanceID) NoStaticUse
Decorate 28(gl_VertexID) PrecisionHigh
Decorate 28(gl_VertexID) BuiltIn VertexId
Decorate 28(gl_VertexID) NoStaticUse
Decorate 29(gl_InstanceID) PrecisionHigh
Decorate 29(gl_InstanceID) BuiltIn InstanceId
Decorate 29(gl_InstanceID) NoStaticUse
2: TypeVoid
3: TypeFunction 2
7: TypeInt 32 1
8: TypePointer Function 7(int)
10: 7(int) Constant 0
16: 7(int) Constant 1
19: 7(int) Constant 10
20: TypeBool
23: TypePointer Input 7(int)
24(gl_VertexID): 23(ptr) Variable Input
25(gl_InstanceID): 23(ptr) Variable Input
14: TypeBool
15: 14(bool) ConstantTrue
20: 7(int) Constant 10
24: 7(int) Constant 1
26: 14(bool) ConstantFalse
27: TypePointer Input 7(int)
28(gl_VertexID): 27(ptr) Variable Input
29(gl_InstanceID): 27(ptr) Variable Input
4(main): 2 Function None 3
5: Label
9(i): 8(ptr) Variable Function
Store 9(i) 10
Branch 11
11: Label
13: 14(bool) Phi 15 5 26 17
LoopMerge 12 None
Branch 13
13: Label
15: 7(int) Load 9(i)
17: 7(int) IAdd 15 16
Store 9(i) 17
Branch 14
14: Label
18: 7(int) Load 9(i)
21: 20(bool) SLessThan 18 19
BranchConditional 21 22 12
Branch 16
16: Label
SelectionMerge 17 None
BranchConditional 13 17 18
18: Label
19: 7(int) Load 9(i)
21: 14(bool) SLessThan 19 20
SelectionMerge 22 None
BranchConditional 21 22 12
22: Label
Branch 11
Branch 17
17: Label
23: 7(int) Load 9(i)
25: 7(int) IAdd 23 24
Store 9(i) 25
Branch 11
12: Label
Branch 6
6: Label
......
Test/baseResults/spv.do-while-continue-break.vert.out
......@@ -5,7 +5,7 @@ Linked vertex stage:
// Module Version 99
// Generated by (magic number): 51a00bb
// Id's are bound by 48
// Id's are bound by 52
Source ESSL 300
1: ExtInstImport "GLSL.std.450"
......@@ -13,97 +13,104 @@ Linked vertex stage:
EntryPoint Vertex 4
Name 4 "main"
Name 9 "i"
Name 15 "A"
Name 22 "B"
Name 25 "C"
Name 31 "D"
Name 34 "E"
Name 36 "F"
Name 43 "G"
Name 46 "gl_VertexID"
Name 47 "gl_InstanceID"
Name 25 "A"
Name 31 "B"
Name 34 "C"
Name 40 "D"
Name 43 "E"
Name 45 "F"
Name 47 "G"
Name 50 "gl_VertexID"
Name 51 "gl_InstanceID"
Decorate 9(i) PrecisionHigh
Decorate 15(A) PrecisionHigh
Decorate 22(B) PrecisionHigh
Decorate 25(C) PrecisionHigh
Decorate 31(D) PrecisionHigh
Decorate 34(E) PrecisionHigh
Decorate 36(F) PrecisionHigh
Decorate 43(G) PrecisionHigh
Decorate 46(gl_VertexID) PrecisionHigh
Decorate 46(gl_VertexID) BuiltIn VertexId
Decorate 46(gl_VertexID) NoStaticUse
Decorate 47(gl_InstanceID) PrecisionHigh
Decorate 47(gl_InstanceID) BuiltIn InstanceId
Decorate 47(gl_InstanceID) NoStaticUse
Decorate 25(A) PrecisionHigh
Decorate 31(B) PrecisionHigh
Decorate 34(C) PrecisionHigh
Decorate 40(D) PrecisionHigh
Decorate 43(E) PrecisionHigh
Decorate 45(F) PrecisionHigh
Decorate 47(G) PrecisionHigh
Decorate 50(gl_VertexID) PrecisionHigh
Decorate 50(gl_VertexID) BuiltIn VertexId
Decorate 50(gl_VertexID) NoStaticUse
Decorate 51(gl_InstanceID) PrecisionHigh
Decorate 51(gl_InstanceID) BuiltIn InstanceId
Decorate 51(gl_InstanceID) NoStaticUse
2: TypeVoid
3: TypeFunction 2
7: TypeInt 32 1
8: TypePointer Function 7(int)
10: 7(int) Constant 0
17: 7(int) Constant 2
18: TypeBool
23: 7(int) Constant 1
27: 7(int) Constant 5
32: 7(int) Constant 3
35: 7(int) Constant 42
37: 7(int) Constant 99
40: 7(int) Constant 19
44: 7(int) Constant 12
45: TypePointer Input 7(int)
46(gl_VertexID): 45(ptr) Variable Input
47(gl_InstanceID): 45(ptr) Variable Input
14: TypeBool
15: 14(bool) ConstantTrue
20: 7(int) Constant 1
22: 7(int) Constant 19
27: 7(int) Constant 2
32: 14(bool) ConstantFalse
36: 7(int) Constant 5
41: 7(int) Constant 3
44: 7(int) Constant 42
46: 7(int) Constant 99
48: 7(int) Constant 12
49: TypePointer Input 7(int)
50(gl_VertexID): 49(ptr) Variable Input
51(gl_InstanceID): 49(ptr) Variable Input
4(main): 2 Function None 3
5: Label
9(i): 8(ptr) Variable Function
15(A): 8(ptr) Variable Function
22(B): 8(ptr) Variable Function
25(C): 8(ptr) Variable Function
31(D): 8(ptr) Variable Function
34(E): 8(ptr) Variable Function
36(F): 8(ptr) Variable Function
43(G): 8(ptr) Variable Function
25(A): 8(ptr) Variable Function
31(B): 8(ptr) Variable Function
34(C): 8(ptr) Variable Function
40(D): 8(ptr) Variable Function
43(E): 8(ptr) Variable Function
45(F): 8(ptr) Variable Function
47(G): 8(ptr) Variable Function
Store 9(i) 10
Branch 11
11: Label
13: 14(bool) Phi 15 5 32 29 32 39
LoopMerge 12 None
Branch 13
13: Label
Store 15(A) 10
16: 7(int) Load 9(i)
19: 18(bool) IEqual 16 17
SelectionMerge 21 None
BranchConditional 19 20 21
20: Label
Store 22(B) 23
Branch 14
Branch 16
16: Label
SelectionMerge 17 None
BranchConditional 13 17 18
18: Label
19: 7(int) Load 9(i)
21: 7(int) IAdd 19 20
Store 9(i) 21
23: 14(bool) SLessThan 21 22
SelectionMerge 24 None
BranchConditional 23 24 12
24: Label
Store 25(C) 17
Branch 21
21: Label
Branch 17
17: Label
Store 25(A) 10
26: 7(int) Load 9(i)
28: 18(bool) IEqual 26 27
28: 14(bool) IEqual 26 27
SelectionMerge 30 None
BranchConditional 28 29 30
29: Label
Store 31(D) 32
Branch 12
Store 31(B) 20
Branch 11
33: Label
Store 34(E) 35
Store 34(C) 27
Branch 30
30: Label
Store 36(F) 37
Branch 14
14: Label
38: 7(int) Load 9(i)
39: 7(int) IAdd 38 23
Store 9(i) 39
41: 18(bool) SLessThan 39 40
BranchConditional 41 42 12
42: Label
35: 7(int) Load 9(i)
37: 14(bool) IEqual 35 36
SelectionMerge 39 None
BranchConditional 37 38 39
38: Label
Store 40(D) 41
Branch 12
42: Label
Store 43(E) 44
Branch 39
39: Label
Store 45(F) 46
Branch 11
12: Label
Store 43(G) 44
Store 47(G) 48
Branch 6
6: Label
Return
......
Test/baseResults/spv.doWhileLoop.frag.out
......@@ -5,7 +5,7 @@ Linked fragment stage:
// Module Version 99
// Generated by (magic number): 51a00bb
// Id's are bound by 34
// Id's are bound by 38
Source GLSL 110
1: ExtInstImport "GLSL.std.450"
......@@ -14,11 +14,11 @@ Linked fragment stage:
Name 4 "main"
Name 10 "color"
Name 12 "BaseColor"
Name 19 "bigColor"
Name 26 "d"
Name 32 "gl_FragColor"
Name 25 "d"
Name 30 "bigColor"
Name 36 "gl_FragColor"
Decorate 12(BaseColor) Smooth
Decorate 32(gl_FragColor) BuiltIn FragColor
Decorate 36(gl_FragColor) BuiltIn FragColor
2: TypeVoid
3: TypeFunction 2
7: TypeFloat 32
......@@ -26,13 +26,15 @@ Linked fragment stage:
9: TypePointer Function 8(fvec4)
11: TypePointer Input 8(fvec4)
12(BaseColor): 11(ptr) Variable Input
18: TypePointer UniformConstant 8(fvec4)
19(bigColor): 18(ptr) Variable UniformConstant
25: TypePointer UniformConstant 7(float)
26(d): 25(ptr) Variable UniformConstant
28: TypeBool
31: TypePointer Output 8(fvec4)
32(gl_FragColor): 31(ptr) Variable Output
17: TypeBool
18: 17(bool) ConstantTrue
24: TypePointer UniformConstant 7(float)
25(d): 24(ptr) Variable UniformConstant
29: TypePointer UniformConstant 8(fvec4)
30(bigColor): 29(ptr) Variable UniformConstant
34: 17(bool) ConstantFalse
35: TypePointer Output 8(fvec4)
36(gl_FragColor): 35(ptr) Variable Output
4(main): 2 Function None 3
5: Label
10(color): 9(ptr) Variable Function
......@@ -40,25 +42,30 @@ Linked fragment stage:
Store 10(color) 13
Branch 14
14: Label
16: 17(bool) Phi 18 5 34 20
LoopMerge 15 None
Branch 16
16: Label
20: 8(fvec4) Load 19(bigColor)
21: 8(fvec4) Load 10(color)
22: 8(fvec4) FAdd 21 20
Store 10(color) 22
Branch 17
17: Label
23: 8(fvec4) Load 10(color)
24: 7(float) CompositeExtract 23 0
27: 7(float) Load 26(d)
29: 28(bool) FOrdLessThan 24 27
BranchConditional 29 30 15
30: Label
Branch 14
Branch 19
19: Label
SelectionMerge 20 None
BranchConditional 16 20 21
21: Label
22: 8(fvec4) Load 10(color)
23: 7(float) CompositeExtract 22 0
26: 7(float) Load 25(d)
27: 17(bool) FOrdLessThan 23 26
SelectionMerge 28 None
BranchConditional 27 28 15
28: Label
Branch 20
20: Label
31: 8(fvec4) Load 30(bigColor)
32: 8(fvec4) Load 10(color)
33: 8(fvec4) FAdd 32 31
Store 10(color) 33
Branch 14
15: Label
33: 8(fvec4) Load 10(color)
Store 32(gl_FragColor) 33
37: 8(fvec4) Load 10(color)
Store 36(gl_FragColor) 37
Branch 6
6: Label
Return
......
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